Biodegradation

Environ Sci Technol, 2001 May 15, 35(10), 2033 - 9
Influence of the nonionic surfactant Brij 35 on the bioavailability of solid and sorbed dibenzofuran; Garcia JM et al.; The effect of the nonionic surfactant Brij 35 on the bioavailability of solid and Teflon-sorbed dibenzofuran for Sphingomonas sp . strain HH19k was studied in simple model systems . Growth with dibenzofuran and dibenzofuran-specific oxygen uptake in surfactant-free media and with Brij 35 above the critical micelle concentration (cmc) were compared with dissolution and desorption in the absence of bacteria . Brij 35 accelerated dissolution and biodegradation of solid dibenzofuran by a factor of 2 . It also enhanced the initial desorption rate of dibenzofuran from Teflon by this factor . Continuously decreasing desorption rates were attributed to slow diffusion of dibenzofuran inside Teflon, leading to depletion of dibenzofuran in the exterior of the Teflon particles . Surprisingly, Brij 35 slowed the initial biodegradation of desorbing dibenzofuran . We propose two processes that led to low bioavailability of sorbed dibenzofuran in the presence of surfactant . First, desorbing dibenzofuran rapidly accumulated in surfactant micelles, leading to reduced truly water-dissolved dibenzofuran concentration as the factor controlling the biodegradation rate . Second, Brij 35 suppressed the contact between bacteria and Teflon . This increased the average diffusion distance of dibenzofuran to the bacteria, which in turn flattened the gradient of the dissolved dibenzofuran concentration between the sorbent and the cells as the driving force for desorption.

Environ Int, 2001 May, 26(5-6), 323 - 6
Persistence of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F) in Ya-Er Lake area, China; Wu WZ et al.; The concentrations of polychlorinaxed dibenzo-p-dioxins and dibenzofurans (PCDD/F) in surface sediment, soil, human hair, and fish muscle from Ya-Er Lake area, China, were analyzed . The results showed that there were very high concentrations of PCDD/F existing in these samples . The results also indicated that Ya-Er Lake, which received a large amount of waste water from a nearby chloroalkali plant, was heavily polluted by PCDD/F . The present study demonstrated that those congeners, which possess at least three chlorine atoms in the lateral position with a fourth chlorine atom in the neighborhood bond of the third single chlorine atom, such as 1,2,7,8-TCDF and 2,3,6,7-TCDF, were very resistant to biodegradation due to the "neighbor effect" of every two chlorine atoms . The present study suggested that human hair may be a suitable alternative bioindicator for detecting PCDD/F exposure.

Water Sci Technol, 2001, 43(3), 299 - 306
Biodegradation of high strength phenolic wastewater using SBR; Yoong ET et al.; This investigation demonstrates the capability of a bench-scale sequencing batch reactor (SBR) to biodegrade an inhibitory substrate at a high loading rate . A SBR loading rate of 3.12 kg phenol.m3 d-1 (2.1 g COD.g-1 MLVSS d-1) with a COD removal efficiency of 97% at a SRT of 4 days and a HRT of 10 hours was achieved; this rate was not reached before . The SBR was operated at 4 hours cycle, including 3 hours react phase . The synthetic wastewater of 1300 mg/L phenol was the sole carbon source . Oxygen uptake rates (OUR) were monitored in-situ at various stages of the SBR . The oxygen mass transfer coefficient, KLa, of 12.6 h-1 was derived from respirometry . Use of respirometry in SBR aided the tracking of the soluble substrate through OUR.

Water Sci Technol, 2001, 43(3), 291 - 8
Explosive biodegradation in soil slurry batch reactors amended with exogenous microorganisms; Shen CF et al.; The present study explores the feasibility of biotreatment of 2,4,6-trinitrotoluene (TNT) and hexahydro-1,3,5-trinitro- 1,3,5-triazine (RDX)-contaminated soils in slurry batch reactors . Radiorespirometric assays showed that anaerobic sludge was able to mineralize 59% RDX to CO2 although significant mineralization of TNT was not observed in all cases . TNT and RDX at concentrations higher than 50 and 100 mg/L respectively were inhibitory to methanogenesis (used as a bioindicator), however, methanogenesis recovered after TNT was transformed into less toxic triaminotoluene . Bioslurry batch reactors containing 40% of contaminated soil (2000 mg RDX and 1000 mg TNT/kg dry soil) were operated under various conditions . Both TNT and RDX were persistent to soil indigenous microbes . Degradation of both TNT and RDX was enhanced by the municipal sludge amendment, although degradation of RDX was only achieved under anaerobic conditions.

Water Sci Technol, 2001, 43(2), 297 - 303
Removal of chlorinated pollutants by a combination of ultrasound and biodegradation; Tiehm A et al.; Chlorinated organic compounds are hazardous pollutants found in waste water, surface water, and ground water . Our study shows that a combination of ultrasonic pretreatment and biodegradation effectively removes the solvent chlorobenzene and the disinfectant 2,4-dichlorophenol, also reduces Adsorbable Organic Halogens (AOX) and Chemical Oxygen Demand (COD) . In our experiments, the ultrasonic dechlorination was not influenced by the presence of other soluble organic compounds like acetate or glucose . Dechlorination of chlorobenzene by ultrasound did not lead to toxic or inhibiting reaction products . More than that, the ultrasonic pretreatment significantly reduced the toxicity of 2,4-dichlorophenol and biological activity was initiated after sonication . Residual organic pollutants after ultrasonic pretreatment were eliminated by biodegradation.

Water Sci Technol, 2001, 43(2), 277 - 84
Aerobic biodegradation of gasoline oxygenates MTBE and TBA; Wilson GJ et al.; MTBE degradation was investigated using a continuously stirred tank reactor (CSTR) with biomass retention (porous pot reactor) operated under aerobic conditions . MTBE was fed to the reactor at an influent concentration of 150 mg/l (1.70 mmol/l) . A second identical reactor was operated as a control under the same conditions with the addition of 2.66 g/l of sodium azide, to kill any biological activity . Results from these experiments suggest that biomass retention is critical to the degradation of MTBE . The rate of MTBE removal was shown to be related to the VSS concentration . MTBE removal exceeded 99.99% when the VSS concentration in the reactor was over 600 mg/l . Results obtained from batch experiments conducted on mixed liquor samples from the porous pot reactor indicate that the individual rates of biodegradation of MTBE and TBA were higher for initial concentrations of 15 mg/l than for concentrations of 5 mg/l . The presence of TBA at lower concentrations did not effect the rate of MTBE degradation, however higher concentrations of TBA did reduce the rate of biodegradation of MTBE . Denaturing Gradient Gel Electrophoresis (DGGE) analysis reveals that the culture consisted of a community of bacterial organisms of about 6 species.

Water Sci Technol, 2001, 43(5), 333 - 40
Substrate interactions during aerobic biodegradation of methane, ethene, vinyl chloride and 1,2-dichloroethenes; Freedman DL et al.; Intrinsic biodegradation of trichloroethene and 1,1,1-trichloroethane in groundwater at a Superfund site in California has been observed . An anaerobic zone exists in the area closest to the source location, yielding the expected complement of reductive dechlorination daughter products, including cis-1,2-dichloroethene (cis-DCE) and vinyl chloride (VC) . Significant levels of methane and ethene were also generated in the anaerobic zone . The groundwater returns to aerobic conditions downgradient of the source, with methane, ethene, VC, and several other compounds still present . Attenuation of VC in the aerobic zone suggests that it is being biodegraded . In this study microcosms were used to evaluate the role of methane and ethene as primary substrates for aerobic biodegradation of VC . Biodegradation of VC was fastest in the bottles containing ethene, with 40 mumol of VC consumed over a 150 day period, compared to approximately 15-20 mumol with methane or a mixture of methane and ethene . VC did not noticeably inhibit ethene biodegradation but did slow the rate of methane use . Methane inhibited ethene metabolism, which apparently caused a reduction in VC biodegradation when methane was present with ethene . These results suggest that ethene plays an important role during in situ natural attenuation of VC under aerobic conditions . Microcosms were also set up with VC alone . Following a 75 day lag period . VC consumption began and subsequent additions were consumed without a lag, suggesting the presence of organisms capable of using VC as a growth substrate . After providing VC alone for nearly 400 days, aliquots of the enrichment culture were used to evaluate its ability to biodegrade cis- and trans-DCE . Both compounds were readily consumed, although addition of VC as the primary substrate was needed to sustain biodegradation of repeated additions . This result suggests that organisms capable of using VC as a sole substrate may play an active role in aerobic natural attenuation of DCEs.

Chemosphere, 2001 May-Jun, 43(4-7), 977 - 84
Estrogenic and dioxin-like potency in each step of a controlled landfill leachate treatment plant in Japan; Behnisch PA et al.; The estrogenic activity (by E-screen bioassay), the concentrations of PCBs, PCDDs/PCDFs (and their resulting toxicity equivalents, TEQ) and several endocrine disrupting chemicals (EDCs: e.g., bisphenol A, nonylphenol, Butyl benzylpthalate (BBP), di-n-butylphthalate (DBP), 17alpha-ethynyl-estradiol or 4-octylphenol) have been analyzed from leachates of each step (before treatment, after biodegradation/sedimentation and after charcoal treatment) of a controlled landfill leachate treatment plant . The comparison of the effluent of the examined landfill leachate treatment plant with water from a nearby river in this study indicated no additional dioxin-like (e.g., TEQ: 0.027 compared to 1.01 pg TEQ/l; PCBs: 1.2 compared to 3.9 ng/l) or estrogenic impact (2.8 compared to 3.5 ng estradiol equivalents EE/l; analyzed by E-screen bioassay) from the leachate treatment plant into the surrounding water environment . The impact of dioxin-like compounds from uncleaned leachates into the final cleaned effluents could be sufficiently reduced by the leachate treatment plant for PCDDs (75%), PCDFs (62%), dioxin-like PCBs (97%), and the sum of TEQ (78%) . The leachate treatment plant also achieved a reduction of the estrogenic activity as determined by E-screen (from 4.8 to 2.8 ng EE/l = 42%), by GC/MS for bisphenol A (>96% and nonylphenol (>98%) or by ELISA for estradiol (>80%) . Additionally, for the validation of the E-screen, five known endocrine disrupting chemicals (EDCs: bisphenol A, BBP, DBP, 17 alpha-ethynyl-estradiol, 4-octylphenol) were analyzed . The EC50 values and estradiol equivalents factors (EEFs) for the five EDCs determined in this study were comparable to previously published data . The combined biological and chemical trace analysis data have provided valuable information on the relative contribution of natural, synthetic, and non-steroidal anthropogenic chemicals to the estrogenic and dioxin-like activity in leachates from a wastewater treatment plant, and water from a nearby river.

Yonsei Med J, 2001 Apr, 42(2), 172 - 9
Characterization of UV-irradiated dense/porous collagen membranes: morphology, enzymatic degradation, and mechanical properties; Lee JE et al.; Collagen-based membranous materials of various shapes (gel, film, sponge) are known to be the most promising materials in terms of facilitating the regeneration of dermal defects . In this study, dense and porous collagen membranes were fabricated using air-drying and freeze-drying processes, respectively, and the effect of ultraviolet (UV) radiation on the degree of membrane crosslinking was evaluated by in vitro biodegradation and mechanical testing . A non-irradiated membrane group was used as the negative control and a glutaraldehyde (GA) treated group as the positive control . Scanning electron microscopy showed that, as the freezing temperature decreased to -196 degrees C, the resultant mean pore sizes also decreased; optimal pore size was obtained at a freezing temperature of -70 degrees C . In vitro biodegradation and mechanical testing demonstrated that GA treatment or 4 hours of exposure to UV radiation significantly increased both resistance to collagenase and mechanical strength versus the untreated controls, regardless of the collagen membrane type (dense or porous) . Our results suggest that UV treatment is a useful tool for the fabrication of collagen membranes designed to be used as dermal dressings.

J Agric Food Chem, 2001 May, 49(5), 2352 - 8
Persistence, fate, and metabolism of {(14)C}metalaxyl in typical Indian soils; Sukul P et al.; The biodegradation of ring-labeled {(14)C}metalaxyl in six Indian soils was examined . The total recovery of radioactivity from soil was 100 +/- 6% of the applied radioactivity . Volatile organics and (14)CO(2) were detected at lower levels . This suggests that neither mineralization nor volatilization is a major route of metalaxyl dissipation . The most rapid degradation of metalaxyl was observed in Bannimantap soil, in which the half-life of metalaxyl was 36 days . An inverse relationship was found when half-lives were plotted against microbial biomass and soil clay content . However, soil total organic carbon did not correlate with metalaxyl persistence . Five metabolites detected by thin-layer chromatography were more polar than metalaxyl.

Chemosphere, 2001 Jun, 43(8), 1071 - 8
Development of a biobarrier for the remediation of PCE-contaminated aquifer; Kao CM et al.; The industrial solvent tetrachloroethylene (PCE) is among the most ubiquitous chlorinated compounds found in groundwater contamination . The objective of this study was to develop a biobarrier system, which includes a peat layer to enhance the anaerobic reductive dechlorination of PCE in situ . Peat was used to supply primary substrate (electron donor) continuously . A laboratory-scale column experiment was conducted to evaluate the feasibility of this proposed system or PCE removal . This experiment was performed using a series of continuous-flow glass columns including a soil column, a peat column, followed by two consecutive soil columns . Anaerobic acclimated sludges were inoculated in all three soil columns to provide microbial consortia for PCE biodegradation . Simulated PCE-contaminated groundwater with a flow rate of 0.25 l/day was pumped into this system . Effluent samples from each column were analyzed for PCE and its degradation byproducts (trichloroethylene (TCE), cis-dichloroethylene (cis-DCE), vinyl chloride (VC), ethylene (ETH), and ethane) . Results show that the decrease in PCE concentrations and production of PCE byproducts were observed over a 65-day operating period . Up to 98%, of PCE removal efficiency was obtained in this passive system . Results indicate that the continuously released organics from peat column enhanced PCE biotransformation . Thus, the developed biobarrier treatment scheme has the potential to be developed into a cost-effective in situ PCE-remediation technology, and can be utilized as an interim step to aid in system scale-up.

J Environ Sci Health A Tox Hazard Subst Environ Eng, 2001, 36(3), 275 - 92
A modeling approach to bioregeneration of granular activated carbon loaded with phenol and 2,4-dichlorophenol; Ha SR et al.; A predictive isotherm model was developed to evaluate the extent of bioregeneration of granular activated carbon loaded with phenol and 2,4-dichlorophenol (2,4-DCP) . Two basic substrates (116 mg/L of phenol and 100 g/L 2,4-DCP) as single solute were prepared . The mixture of them was provided to bisolute system for assessing the competitive adsorption . The effect of by-products, which were generated during biodegradation of substrate and measured as COD, on bioregeneration in the bisolute was investigated . Freundlich adsorption parameters (Kads and 1/n) of 2,4-DCP were obviously higher than those of phenol in both single and bisolute . By-products in the bulk solution brought an adverse effect on adsorption capacity of GAC in all cases . By taking into account the by-product effect on adsorption, the Freundlich isotherms were used to formulate a predictive model of bioregeneration . Simulated results showed good consistency of observed results . Practical relevant of the proposed model for assessing of bioregeneration in the wastewater treatment was discussed by applying model to the BAC-SBR in the steady-state operation.

J Ind Microbiol Biotechnol, 2001 Jan, 26(1/2), 83 - 89
Solid-state (13)C NMR spectroscopic, chemolytic and biological assessment of pretreated municipal solid waste; Pichler M et al.; In Central Europe, composting and anaerobic digestion of municipal solid waste (MSW) is used as pretreatment before landfilling to reduce landfill emissions . MSW samples were analyzed before, during, and after pretreatment to assess the stability of the organic matter . Chemolytic, nuclear magnetic resonance (NMR) spectroscopic, and respiration parameters were correlated to evaluate a substitution of the time-consuming respiration analysis by chemical parameters . (13)C cross polarization magic angle spinning (CPMAS) NMR spectroscopy showed a preferential biodegradation of O-alkyl carbon (carbohydrates) and a selective accumulation of plastics during all pretreatments, confirming findings from chemolytic analyses . Principal component analysis exhibited a strong association between the respiration rate, the carbohydrate content, and the O-alkyl C content, corroborating that carbohydrates are the most important compounds of MSW with regard to the emission potential . Rank correlation (Spearman) also showed strong relationships between the respiration rate and the content of carbohydrates (r=0.75) and of O-alkyl C (r=0.72).

J Ind Microbiol Biotechnol, 2001 Jan, 26(1/2), 22 - 34
19F NMR metabolomics for the elucidation of microbial degradation pathways of fluorophenols; Boersma MG et al.; Of all NMR-observable isotopes (19)F is the one most convenient for studies on the biodegradation of environmental pollutants and especially for fast initial metabolic screening of newly isolated organisms . In the past decade we have identified the (19)F NMR characteristics of many fluorinated intermediates in the microbial degradation of fluoroaromatics including especially fluorophenols . In the present paper we give an overview of results obtained for the initial steps in the aerobic microbial degradation of fluorophenols, i.e . the aromatic hydroxylation to di-, tri- or even tetrahydroxybenzenes ultimately suitable as substrates for the second step, ring cleavage by dioxygenases . In addition we present new results from studies on the identification of metabolites resulting from reaction steps following aromatic ring cleavage, i.e . resulting from the conversion of fluoromuconates by chloromuconate cycloisomerase . Together the presented data illustrate the potential of the (19)F NMR technique for (1) fast initial screening of biodegradative pathways, i.e . for studies on metabolomics in newly isolated microorganisms, and (2) identification of relatively unstable pathway intermediates like fluoromuconolactones and fluoromaleylacetates.

J Ind Microbiol Biotechnol, 2001 Jan, 26(1/2), 2 - 8
In situ (1)H NMR study of the biodegradation of xenobiotics: application to heterocyclic compounds; Delort AM et al.; In vivo or in situ nuclear magnetic resonance (NMR) offers a powerful tool to study the degradation of xenobiotics by microorganisms . Most studies reported are based on the use of heteronuclei, and experiments with xenobiotics have been limited because specifically labeled xenobiotics are not commercially available, with the exception of (19)F and (31)P . (1)H NMR is, thus, of great interest in this area . To avoid problems caused by the presence of water and intrinsic metabolite signals, some studies were performed using a deuterated medium or specific detection of protons linked to the (13)C-(15)N enriched pattern . We report here the application of in situ (1)H NMR, performed directly on culture media, to study the metabolism of heterocyclic compounds . In this review, we show that a common pathway is involved in the biodegradation of morpholine, piperidine, and thiomorpholine by Mycobacterium aurum MO1 and Mycobacterium sp . RP1 . In all cases, the first step is the cleavage of the C-N bond, which results in an amino acid . Thiomorpholine is first oxidized to sulfoxide before the opening of the ring . The second step is the deamination of the intermediate amino acid, which leads to the formation of a diacid . We have shown that the cleavage of the C-N bond and the oxidation of thiomorpholine are initiated by reactions involving a cytochrome P450.

J Chromatogr A, 2001 Apr 27, 915(1-2), 129 - 37
Screening for transformation products of pesticides using tandem mass spectrometric scan modes; Steen RJ et al.; The applicability of tandem mass spectrometric (MS-MS) scan modes such as constant neutral-loss and precursor-ion scanning to screen for unknown transformation products (TPs) of pesticides at environmentally relevant concentrations (low-microng/l level) is studied . The selection of the MS-MS scan modes is based on the product-ion scan of the parent pesticide, and TPs are detected which are unaltered in the part of the structure concerned . The screening approach is applied to a surface water sample spiked with atrazine and three known TPs at a level of 3 microg/l to study the possibility to extract the TPs from the total ion chromatogram . Next, the approach is used to identify unknown TPs formed after (bio)degradation of two test compounds, fenchlorazole-ethyl (FCE) and furathiocarb (FTC) . By using the precursor-ion scan mode, two TPs were detected after biodegradation of FCE, fenchlorazole-methyl and fenchlorazole; in surface water only fenchlorazole was found . The constant neutral-loss scan mode was used to identify carbofuran as TP of FTC . The added value of the proposed procedure is the increased selectivity at the cost of sensitivity . Best results are, therefore, obtained for samples which contain large amounts of matrix constituents.

Biochem Soc Trans, 2001 May, 29(Pt 2), 111 - 6
Lignin peroxidase structure and function; Piontek K et al.; Lignin peroxidase (LiP) plays a central role in the biodegradation of the plant cell wall constituent lignin . LiP is able to oxidize aromatic compounds with redox potentials higher than 1.4 V (NHE) by single electron abstraction, but the exact redox mechanism is still poorly understood . The finding in our laboratory that the Cbeta-atom of Trp171 carries a unique modification led us to initiate experiments to investigate the role of this residue . These experiments, employing crystallography, site-directed mutagenesis, protein chemistry, spin-trapping and spectroscopy, yielded the following results: (i) Trp171 is stereospecifically hydroxylated at its Cbeta-atom as the result of an auto-catalytic process, which occurs under turnover conditions in the presence of hydrogen peroxide . (ii) Evidence for the formation of a Trp171 radical intermediate has been obtained using spin-trapping, in combination with peptide mapping and protein crystallography . (iii) Trp171 is very likely to be involved in electron transfer from natural substrates to the haem cofactor via LRET . (iv) Mutagenetic substitution of Trp171 abolishes completely the oxidation activity for veratryl alcohol, but not for artificial substrates . (v) Structural changes in response to the mutation are marginal . Therefore the lack of activity is due to the absence of the redox active indole side chain.

J Chromatogr A, 2001 Apr 13, 913(1-2), 205 - 8
Preliminary investigation of the application of on-line membrane extraction of trifluoroacetic acid as an aid to improvement of negative ion electrospray mass spectrometry data; New AP et al.; We have recently investigated the biodegradation of a number of acidic aromatic compounds that give excellent chromatography using trifluoroacetic acid (TFA) based HPLC methods . Unfortunately HPLC methods using TFA are not usually compatible with detection by negative ion mass spectrometry as TFA suppresses ionisation of the analyte during the electrospray process . We present a preliminary investigation of the use of an anion-exchange micro-membrane suppressor to remove TFA on-line post column with the aim of improvement of mass spectral data using an aromatic acid as an example, Thus LC-MS using a TFA based HPLC method with negative ion mass spectral detection is shown to be possible with good sensitivity.

J Chromatogr A, 2001 Apr 13, 913(1-2), 205 - 8
Preliminary investigation of the application of on-line membrane extraction of trifluoroacetic acid as an aid to improvement of negative ion electrospray mass spectrometry data; New AP et al.; We have recently investigated the biodegradation of a number of acidic aromatic compounds that give excellent chromatography using trifluoroacetic acid (TFA) based HPLC methods . Unfortunately HPLC methods using TFA are not usually compatible with detection by negative ion mass spectrometry as TFA suppresses ionisation of the analyte during the electrospray process . We present a preliminary investigation of the use of an anion-exchange micro-membrane suppressor to remove TFA on-line post column with the aim of improvement of mass spectral data using an aromatic acid as an example, Thus LC-MS using a TFA based HPLC method with negative ion mass spectral detection is shown to be possible with good sensitivity.

Environ Sci Technol, 2001 Jan 1, 35(1), 102 - 7
Analysis of long-side-chain alkylaromatics in crude oil for evaluation of their fate in the environment; Dutta TK et al.; It has long been believed that the n-hexane fraction of crude oil only contains saturates . However, we found that one-third of its content was aromatics with long alkyl side chains and that these aromatics could be separated from the saturates by preparative thin-layer chromatography . The separated alkylaromatic fraction was characterized by UV-visible, NMR and mass spectrometries . A gas chromatographic-mass spectrometric analysis showed the presence of a homologous series of long-side-chain n-alkylaromatics, namely mono-, di-, and tri-n-alkylbenzenes in the C7-C27 range (the subscript to C indicates the total number of carbon atoms in the alkyl side chain) and di- and tri-n-alkylbenzothiophenes in the C3-C22 range . The biodegradation of these crude oil components by a natural bacterial population in seawater and their photooxidation by artificial sunlight were investigated . The n-alkylbenzenes were found to be quite susceptible to biodegradation but resistant to photooxidation, whereas the n-alkylbenzothiophenes were almost completely photooxidized and substantially biodegraded.

Environ Sci Technol, 2001 Mar 1, 35(5), 901 - 7
Variability in carbon isotopic fractionation during biodegradation of chlorinated ethenes: implications for field applications; Slater GF et al.; Stable carbon isotopic analysis has the potential to assess biodegradation of chlorinated ethenes . Significant isotopic shifts, which can be described by Rayleigh enrichment factors, have been observed for the biodegradation of trichloroethlyene (TCE), cis-dichloroethylene (cDCE), and vinyl chloride (VC) . However, until this time, no systematic investigation of isotopic fractionation during perchloroethylene (PCE) degradation has been undertaken . In addition, there has been no comparison of isotopic fractionation by different microbial consortia, nor has there been a comparison of isotopic fractionation by consortia generated from the same source, but growing under different conditions . This study characterized carbon isotopic fractionation during reductive dechlorination of the chlorinated ethenes, PCE in particular, for microbial consortia from two different sources growing under different environmental conditions in order to assess the extent to which different microbial consortia result in different fractionation factors . Rayleigh enrichment factors of -13.8@1000, -20.4@1000, and -22.4@1000 were observed for TCE, cDCE, and VC, respectively, for dechlorination by the KB-1 consortium . In contrast, isotopic fractionation during reductive dechlorination of perchloroethylene (PCE) could not always be approximated by a Rayleigh model . Dechlorination by one consortium followed Rayleigh behavior (epsilon = -5.2), while a systematic change in the enrichment factor was observed over the course of PCE degradation by two other consortia . Comparison of all reported enrichment factors for reductive dechlorination of the chlorinated ethenes shows significant variation between experiments . Despite this variability, these results demonstrate that carbon isotopic analysis can provide qualitative evidence of the occurrence and relative extent of microbial reductive dechlorination of the chlorinated ethenes.

J Contam Hydrol, 2001 May, 49(1-2), 151 - 69
An assessment of natural biotransformation of petroleum hydrocarbons and chlorinated solvents at an aquifer plume transect; Skubal KL et al.; Field biogeochemical characterization and laboratory microcosm studies were performed to assess the potential for future biotransformation of trichloroethylene (TCE) and toluene in a plume containing petroleum hydrocarbons and chlorinated solvents at the former Wurtsmith Air Force Base in Oscoda, MI . In situ terminal electron accepting processes (TEAPs), contaminant composition and microbial phylogeny were studied at a plume transect 100 m downgradient of the source . The presence of reduced electron acceptors, relevant microbial communities, and elevated dissolved methane and carbon dioxide concentrations at the transect, as well as downgradient accumulation of BTEX metabolites and dechlorination products, indicated that past or current reductive dechlorination at the transect was likely driven by BTEX biodegradation in the methanogenic zone . However, TCE and toluene mineralization in sediment-groundwater microcosms without added electron acceptors did not exceed 5% during 300 days of incubation and was nearly invariant with original sediment TEAP, even following amendments of nitrogen and phosphorus . Mineralization rates were on the order of 0.0015-0.03 mumol/g day . After 8 months, microcosms showed evidence of methanogenesis, but CH4 and CO2 production arose from the degradation of contaminants other than toluene . Cis-dichloroethylene was observed in only one methanogenic microcosm after more than 500 days . It appears likely that spatially and temporally dynamic redox zonation at the plume transect will prevent future sustained reductive dehalogenation of highly chlorinated solvents, for during the course of a year, the predominant TEAP at the highly contaminated water table shifted from methanogenesis to iron- and sulfate-reduction . It is recommended that biotransformation studies combine considerations of long-term, spatially relevant changes in redox zonation with laboratory-scale studies of electron donor utilization and cometabolic substrate transformation to yield a more accurate assessment of natural bioattenuation of specific pollutants in aquifers contaminated by undefined organic waste mixtures.

J Contam Hydrol, 2001 May, 49(1-2), 111 - 49
A controlled field experiment on groundwater contamination by a multicomponent DNAPL: creation of the emplaced-source and overview of dissolved plume development; Rivett MO et al.; A unique field experiment has been undertaken at the CFB Borden research site to investigate the development of dissolved chlorinated solvent plumes from a residual dense non-aqueous phase liquid (DNAPL) source . The "emplaced-source" tracer test methodology involved a controlled emplacement of a block-shaped source of sand containing chlorinated solvents below the water table . The gradual dissolution of this residual DNAPL solvent source under natural aquifer conditions caused dissolved solvent plumes of trichloromethane (TCM), trichloroethene (TCE) and perchloroethene (PCE) to continuously develop down gradient . Source dissolution and 3-D plume development were successfully monitored via 173 multilevel samplers over a 475-day tracer test period prior to site remediation research being initiated . Detailed groundwater level and hydraulic conductivity data were collected . Development of plumes with concentrations spanning 1-700,000 micrograms/1 is described and key processes controlling their migration identified . Plumes were observed to be narrow due to the weakness of transverse dispersion processes and long due to advection and significant longitudinal dispersion, very limited sorptive retardation and negligible, if any, attenuation due to biodegradation or abiotic reaction . TCM was shown to be essentially conservative, TCE very nearly conservative and PCE, consistent with its greater hydrophobicity, more retarded yet having a greater mobility than observed in previous Borden field tests . The absence of biodegradation was ascribed to the prevailing aerobic conditions and lack of any additional biodegradable carbon substrates . The transient groundwater flow regime caused significant transverse lateral plume movement, plume asymmetry and was likely responsible for most of the, albeit limited, transverse horizontal plume spreading . In agreement with the widespread incidence of extensive TCE and PCE plumes throughout the industrialized world, the experiment indicates such solvent plumes are likely to be highly mobile and persistent, at least in aquifers that are aerobic and have low sorption potential (low foc content).

Environ Toxicol Chem, 2001 Feb, 20(2), 223 - 30
Pyrene and chrysene fate in surface soil and sand microcosms; Roper JC et al.; Polycyclic aromatic hydrocarbons (PAHs) are major components of wastes from municipal gas plants and many wood preservatives . Soil contaminated with these wastes is a potential threat to human health because of the carcinogenicity of many PAHs . This study follows the fate of two four-ring PAHs, pyrene and chrysene, in three matrices: an adapted soil (obtained from a site contaminated with PAHs for more than 75 years), an uncontaminated soil (with and without an inoculum of adapted soil), and sand mixed with an inoculum of adapted soil . Radiolabeled pyrene, chrysene, and salicylic acid (a metabolite of PAH biodegradation) were used to trace the mineralization, transformation, extractability, and formation of an unextractable residual over time . Linear approximations of the rates of these processes were made . High-performance liquid chromatography (HPLC) analysis of extracts from inoculated soil showed the transient formation of two known metabolites: 1-hydroxypyrene (from pyrene) and 1-hydroxy-2-naphthoic acid (from chrysene) . The amount of extractable label diminished steadily over the course of the study in systems that were not inhibited with sodium azide, whereas the amount of extractable label remained relatively constant in inhibited systems . Correspondingly, the amount of nonextractable residual label generally increased during each incubation in uninhibited systems, whereas the amount of this residual label remained relatively constant in inhibited systems . In contrast, the rate and extent of mineralization varied widely across matrix types . This suggests that alterations of the PAH that impact extractability and residual formation are common, in contrast to mineralization, which was apparently limited to adapted communities.

Environ Toxicol Chem, 2001 Mar, 20(3), 644 - 51
Sperm cell toxicity test using sea urchin Paracentrotus lividus lamarck (Echinodermata: Echinoidea): sensitivity and discriminatory ability toward anionic and nonionic surfactants; Ghirardini AV et al.; A reliable sperm cell toxicity test procedure has been developed for the Mediterranean sea urchin Paracentrotus lividus . The sensitivity and discriminatory ability of the test were investigated with regard to surfactants and their biotransformation products . Aromatic and aliphatic surfactants of anionic (linear alkylbenzene sulfonates {LAS}) and nonionic (alcohol polyethoxylates {AE} and nonylphenol polyethoxylates {NPE}) types and their aerobic biodegradation products, i.e., sulfophenylcarboxylates (SPC), polyethylene glycols (PEG), carboxylated polyethylene glycols (PEGC), carboxylated AE (AEC), and nonylphenol (NP), were examined in order to elucidate the influence of their molecular structure on toxicity . Experimental results reveal that the sperm cell test showed good discriminatory ability among all tested compounds, median effective concentration (EC50) values differing by about four orders of magnitude . The toxicity of anionic surfactants depends on the length of the alkyl chain and that of nonionic surfactants is due to their length and branching . Much lower toxicity was shown by aerobic biodegradation products in comparison with that of their parent compounds, with the exception of NP . The obtained EC50s were comparable with available literature data and constitute new toxicity data regarding surfactants for sea urchins.

Environ Sci Technol, 2001 Feb 15, 35(4), 676 - 81
Monitoring biodegradation of methyl tert-butyl ether (MTBE) using compound-specific carbon isotope analysis; Hunkeler D et al.; Methyl tert-butyl ether (MTBE), the most common gasoline oxygenate, is frequently detected in surface water and groundwater . The aim of this study was to evaluate the potential of compound-specific isotope analysis to assess in situ biodegradation of MTBE in groundwater . For that purpose, the effect of relevant physical and biological processes on carbon isotope ratios of MTBE was evaluated in laboratory studies . Carbon isotope fractionation during organic phase/gas-phase partitioning (0.50 +/- 0.15@1000), aqueous phase/gas-phase partitioning (0.17 +/- 0.05@1000), and organic phase/aqueous-phase partitioning (0.18 +/- 0.24@1000) was small in comparison to carbon isotope fractionation measured during biodegradation of MTBE in microcosms based on aquifer sediments of the Borden site . In experiments with MTBE as the only substrate and a cometabolic experiment with 3-methypentane as primary substrate, MTBE became enriched in 13C by 5.1 to 6.9@1000 after 95 to 97% degradation . For both experiments, similar isotopic enrichment factors were obtained (-1.52 +/- 0.06 to -1.97 +/- 0.05@1000) . Biodegradation of TBA, which accumulated transiently in the cometabolic microcosms, was also accompanied by carbon isotope fractionation, with an isotopic enrichment factor of -4.21 +/- 0.07@1000 . This study suggests that carbon isotope analysis is a potential tool to trace in situ biodegradation of MTBE and TBA and thus to better understand the fate of these contaminants in the environment.

Environ Sci Technol, 2001 Jan 15, 35(2), 312 - 7
Substrate interactions in BTEX and MTBE mixtures by an MTBE-degrading isolate; Deeb RA et al.; Groundwater contaminant plumes from recent accidental gasoline releases often contain the fuel oxygenate MTBE (methyl tert-butyl ether) together with BTEX (benzene, toluene, ethylbenzene, o-xylene, m-xylene and p-xylene) compounds . This study evaluates substrate interactions during the aerobic biotransformation of MTBE and BTEX mixtures by a pure culture, PM1, capable of utilizing MTBE for growth . PM1 was unable to degrade ethylbenzene and two of the xylene isomers at concentrations of 20 mg/L following culture growth on MTBE . In addition, the presence of 20 mg/L of ethylbenzene or the xylenes in mixtures with MTBE completely inhibited MTBE degradation . When MTBE-grown cells of PM1 were exposed to MTBE/benzene and MTBE/toluene mixtures, MTBE degradation proceeded, while the degradation of benzene and toluene was delayed for several hours . Following this initial lag, benzene and toluene were degraded rapidly, while the rate of MTBE degradation slowed significantly . MTBE degradation did not increase to previous rates until benzene and toluene were almost entirely degraded . The lag in benzene and toluene degradation was presumably due to the induction of the enzymes necessary for BTEX degradation . Once these enzymes were induced, sequential additions of benzene or toluene were degraded rapidly, and growth on benzene and toluene was observed . The results of this study suggest that BTEX and MTBE degradation occurs primarily via two independent and inducible pathways . If subsurface microbial communities behave similarly to the culture used in this study, the observed severe inhibition of MTBE degradation by ethylbenzene and the xylenes and the partial inhibition by benzene and toluene suggest thatthe biodegradation of MTBE in subsurface environments would most likely be delayed until MTBE has migrated beyond the BTEX plume.

Biomed Sci Instrum, 2001, 37, 275 - 80
Biocompatibility of steroid-HA delivery system using adult castrated rams as a model; Benghuzzi H et al.; The objective of this study was to analyze the fibrous tissue surrounding dihydrotestosterone (DHT loaded HA devices implanted subcutaneously (S/C) in adult castrated rams . The microcrystals of HA were prepared by following standard laboratory procedure . Housing, surgical implantation and bleeding procedure of all rams used in this study was conducted according to the NIH guideline and approval of UCUCA . A total of 11 rams were castrated by elastrator rings within a week after birth . At 7 months of age the animals were randomly divided into three groups . Group 1 rams (n = 4) were not treated and served as the control group . Rams in group 2 (n = 3) were implanted s.c . with two HA capsules (80 mg DHT/capsule) . Each ram (n = 3) in group 3 was implanted with two empty HA capsules and served as a sham group . All animals were housed together throughout this study and water, high quality hay and grain were given ad libitum . The sterilized ceramics were inserted S/C through a single incision using standard aseptic surgical techniques . Gross, radiographic and histological examinations of the site of implantation did not show any untoward reactions during the entire investigation . Histopathological evaluation have revealed that all HA implants were encapsulated with hyaline fibrous tissue at the end of two weeks, and the degree of encapsulation increased with time . Results collected from this investigation showed that the passage of DHT through HA capsules started within 3 days after implantation . Furthermore, sustained delivery of DHT by means of HA devices at levels ranging between 1.4-3.3 ng/ml imposed continuous negative feedback on post-castration rise in serum LH and FSH secretion . Representative retrieved implants showed slight degradation of the implant (27% +/- 38) and increased erosion at the sharp edges with time was observed . Light and electron microscopic evaluation demonstrated that at the end of four weeks postimplantation, a well developed granulation tissue is seen surrounding the implants . The thin developing fibrous capsule infiltrated with macrophages and numerous small and large capillaries were observed . A well-developed fibrous capsule formed at 6 months postimplantation . Four different layers were observed: (i) the HA tissue layer contains macrophages, some mononuclear leukocytes, and fibroblasts indicative of the chronic inflammatory responses, (ii) the fibrous capsule layer is composed of longitudinally oriented fibroblasts and mature collagen fibers, (iii) the vascularization layer contains numerous large and small capillaries, and (iii) the outer side of the fibrous capsule predominately composed of adipose tissue . Data obtained from this study suggest that lack of vascularization at the immediate HA tissue layer and the fibrous capsule layer may function to retard the rapid release of DHT from the HA implants . This retardation of DHT release from HA implants by the formation of fibrous capsule is needed to compensate for the macropores formed during the biodegradation of the implants.

Crit Rev Oral Biol Med, 2001, 12(2), 136 - 51
Relation of dental composite formulations to their degradation and the release of hydrolyzed polymeric-resin-derived products; Santerre JP et al.; This article reviews the principal modes of dental composite material degradation and relates them to the specific components of the composites themselves . Particular emphasis is placed on the selection of the monomer resins, the filler content, and the degree of monomer conversion after the clinical materials are cured . Loss of mechanical function and leaching of components from the composites are briefly described, while a more detailed description is provided of studies that have considered the chemical breakdown of materials by agents that are present in the oral cavity, or model the latter . Specific attention will be given to the hydrolysis process of monomer and composite components, i.e., the scission of condensation-type bonds (esters, ethers, amides, etc.) that make up the monomer resins, following reaction of the resins with water and salivary enzymes . A synopsis of enzyme types and their sources is outlined, along with a description of the work that supports their ability to attack and degrade specific types of monomer systems . The methods for the study of biodegradation effects are compared in terms of sensitivity and the information that they provide . The impact of biodegradation on the ultimate biocompatibility of current materials is discussed from the perspective of what is known to date and what remains to be studied . The findings of the past decade clearly indicate that there are many reasons to probe the issue of biochemical stability of composite resins in the oral cavity . The challenge will now be to have both industry and government agencies take a pro-active approach to fund research in this area, with the expectation that these studies will lead to a more concise definition of biocompatibility issues related to dental composites . In addition, the acquired information from such studies will generate the development of alternate polymeric chemistries and composite formulations that will require further investigation for use as the next generation of restorative materials with enhanced biostability.

Environ Toxicol Chem, 2001 Apr, 20(4), 899 - 906
Reevaluating the free-ion activity model of trace metal toxicity toward higher plants: experimental evidence with copper and zinc; Parker DR et al.; Across a diverse spectrum of organisms, the absorption and toxicity of trace elements are usually correlated with the activity of the free metal ion, but reported exceptions to this generalization are increasing . For the first time, we tested the validity of the free-ion activity model (FIAM) in the case of terrestrial plants and organic acids that may be abundant in the soil solution and rhizosphere . Short-term (48-h) root elongation of wheat (Triticum aestitvum L.) in a simple medium (2 mM CaCl2, pH 6.0) was used to probe the toxicity of Cu and Zn in the presence of malonate, malate, and citrate . Precautions were taken to prevent biodegradation of the organic acids, and its absence was confirmed by ion chromatography . Copper speciation was verified using a Cu-selective ion electrode, and published stability constants were modified to improve agreement between measured and calculated Cu2+ activities . With additions of both malonate and malate, Cu toxicity was alleviated but not to the extent predicted by the FIAM; the Cu-ligand complexes seemingly contributed to the toxicity . No such departures were observed with citrate and Cu nor with any of the three ligands in combination with Zn . Thus, exceptions to the FIAM occur with higher plants as well as with aquatic biota but do not seem to occur in a predictable or systematic fashion with respect to metal or organic acid under investigation . Several possible explanations for the observed departures from the FIAM are discussed, including the possibility of accidental cotransport of metal and ligand into the cytoplasm.

Biomaterials, 2001 Jun, 22(11), 1385 - 91
Repetitive subcutaneous implantation of different types of (biodegradable) biomaterials alters the foreign body reaction; van Luyn MJ et al.; In the present study two biodegradable materials (cross-linked collagens) and two non-biodegradable materials (polyurethane and silicone) were applied in a repetitive subcutaneous implantation model in rats . In contrast to the first challenge, the second challenge with the same type of material, but at a different subcutaneous site of the same animal, induced an increase of macrophages and giant cells inside the biodegradable materials . Additionally, only after the second challenge clusters and accumulations of plasma cells were present in the surrounding tissue of each type of material . In the same areas an increase of MHC II expression was measured by immunocytochemistry . Differences in the numbers of macrophages and T cells were not observed around the explants . Undifferentiated B cells or NK cells were not present at any time point . The results indicate that alterations observed after the second challenge did not depend on biodegradation of the materials . Significance of these findings should be considered in view of increased and repetitive use of the same type of biomaterial (possibly for different application sites) for implantation in patients.

J Biomater Sci Polym Ed, 2001, 12(1), 77 - 88
Controlled release of growth factors based on biodegradation of gelatin hydrogel; Yamamoto M et al.; To develop a carrier for the controlled release of biologically-active growth factors, biodegradable hydrogels were prepared through glutaraldehyde cross-linking of gelatin with isoelectric points (IEP) of 5.0 and 9.0, i.e . 'acidic' and 'basic' gelatins, respectively . Radioiodinated growth factors were used to investigate their sorption and desorption from the hydrogel of both types of gelatin . Basic fibroblast growth factor (bFGF) and transforming growth factor-beta1 (TGF-beta1) were well sorbed with time to the acidic gelatin hydrogel, while less sorption was observed for the basic gelatin hydrogel . This could be explained in terms of the electrostatic interaction between the growth factors and the acidic gelatin . However, bone morphogenetic protein-2 (BMP-2) and vascular endothelial growth factor (VEGF), though their IEPs are higher than 7.0, were sorbed to the acidic gelatin hydrogel to a smaller extent than the two other growth factors . Under in vitro non-degradation conditions, approximately 20% of the incorporated bFGF and TGF-beta1 was desorbed from the hydrogels within the initial 40 min, followed by no further substantial desorption, whereas large initial desorption was observed for BMP-2 and VEGF . When implanted in the back subcutis of mice, gelatin hydrogels were degraded over time . Each growth factor was retained in vivo being incorporated in the acidic gelatin hydrogel: the smaller the in vitro desorption amount from the hydrogel, the longer the in vivo retention time . The in vivo profile of bFGF and TGF-beta1 retention was in good accordance with that of the hydrogel . These findings indicate that the growth factor immobilized to the acidic gelatin hydrogel through ionic interaction was released in vivo as a result of hydrogel degradation.

J Biomater Sci Polym Ed, 2001, 12(1), 21 - 34
Synthesis, characterization, biodegradation, and drug delivery application of biodegradable lactic/glycolic acid polymers . Part II: biodegradation; Wu XS et al.; A series of previously-synthesized lactic/glycolic acid polymers (PLGA) with various molar ratios of lactic to glycolic acid and various molecular weights were further studied with regard to their biodegradation behavior, and in particular, the factors affecting the biodegradation rate . The biodegradation of PLGA is affected by many factors including polymer composition, molecular weight, and nature of the incubating media . The biodegradation rate of PLGA containing higher content of lactic acid moiety is lower than those containing a lower content of lactic acid moiety . PLGAs with a higher molecular weight, degrade faster than those with a lower molecular weight, i.e . the molecular weight decreases more rapidly for higher molecular weight PLGAs than their lower molecular weight counterparts . Nature or properties of the hydrolysis/incubating media may have an effect on the biodegradation of PLGAs . A basic medium may slow down the biodegradation of PLGA in comparison with samples in an acidic medium . The rate of pH reduction for the incubating medium can be divided into three deferent phases, giving an inverted S-type pH profile for the non-buffered incubating media.

Sheng Wu Yi Xue Gong Cheng Xue Za Zhi, 2001 Mar, 18(1), 119 - 22
{Applied researches on polylactide internal fixation devices}; Duan H et al.; Nowadays, more and more basic and clinical researches on polylactide internal fixators were carried out in China . In this paper are reviewed the researches of polylactide acid(PLA), including its physical and chemical characters, biodegradation, absorption and mechanical properties, effects on fracture healing, and clinical application . Some problems that have not been solved are high-lighted and discussed . Also dealt with are some researches of PLA in future.

Rev Environ Contam Toxicol, 2001, 169, 123 - 64
Biodegradation kinetics for pesticide exposure assessment; Wolt JD et al.; Understanding pesticide risks requires characterizing pesticide exposure within the environment in a manner that can be broadly generalized across widely varied conditions of use . The coupled processes of sorption and soil degradation are especially important for understanding the potential environmental exposure of pesticides . The data obtained from degradation studies are inherently variable and, when limited in extent, lend uncertainty to exposure characterization and risk assessment . Pesticide decline in soils reflects dynamically coupled processes of sorption and degradation that add complexity to the treatment of soil biodegradation data from a kinetic perspective . Additional complexity arises from study design limitations that may not fully account for the decline in microbial activity of test systems, or that may be inadequate for considerations of all potential dissipation routes for a given pesticide . Accordingly, kinetic treatment of data must accommodate a variety of differing approaches starting with very simple assumptions as to reaction dynamics and extending to more involved treatments if warranted by the available experimental data . Selection of the appropriate kinetic model to describe pesticide degradation should rely on statistical evaluation of the data fit to ensure that the models used are not overparameterized . Recognizing the effects of experimental conditions and methods for kinetic treatment of degradation data is critical for making appropriate comparisons among pesticide biodegradation data sets . Assessment of variability in soil half-life among soils is uncertain because for many pesticides the data on soil degradation rate are limited to one or two soils . Reasonable upper-bound estimates of soil half-life are necessary in risk assessment so that estimated environmental concentrations can be developed from exposure models . Thus, an understanding of the variable and uncertain distribution of soil half-lives in the environment is necessary to estimate bounding values . Statistical evaluation of measures of central tendency for multisoil kinetic studies shows that geometric means better represent the distribution in soil half-lives than do the arithmetic or harmonic means . Estimates of upper-bound soil half-life values based on the upper 90% confidence bound on the geometric mean tend to accurately represent the upper bound when pesticide degradation rate is biologically driven but appear to overestimate the upper bound when there is extensive coupling of biodegradation with sorptive processes . The limited data available comparing distribution in pesticide soil half-lives between multisoil laboratory studies and multilocation field studies suggest that the probability density functions are similar . Thus, upper-bound estimates of pesticide half-life determined from laboratory studies conservatively represent pesticide biodegradation in the field environment for the purposes of exposure and risk assessment . International guidelines and approaches used for interpretations of soil biodegradation reflect many common elements, but differ in how the source and nature of variability in soil kinetic data are considered . Harmonization of approaches for the use of soil biodegradation data will improve the interpretative power of these data for the purposes of exposure and risk assessment.

Environ Technol, 2001 Apr, 22(4), 409 - 27
Partial oxidation by ozone to remove recalcitrance from wastewaters--a review; Alvares AB et al.; Xenobiotic organics produced by modern industrial processes resist conventional biological wastewater treatment . Ozone pretreatment to improve biodegradation via partial oxidation is a potential solution for this recalcitrance . Ozone forms no additional sludge, removes colour and has two modes of action that can be utilised according to the wastewater constituents . The preozonation of a variety of wastewaters and model compounds is reviewed here . Of the industrial processes examined, the associated recalcitrant organic compounds were generally halogenated heterocyclic or nitrogenous aromatics, aliphatic polymers or polyaromatics . Initial optimisation of ozone dose ensured the occurrence of partial oxidation, where over 90% parent compound transformation was required to give best results in the subsequent biological process . Ozonation intermediate and end-products included ketones, aldehydes and organic acids that were more biodegradable than the parent compounds . Biodegradability improvement was assessed using TOC, COD, BOD, BOD/COD ratio and OUR . Actual process feasibility and performance was evaluated using various combined ozonation-biodegradation trials; textile dying and finishing effluent being one area of application . Kinetic studies of chemical and biological stages facilitated process optimisation and can assist scale-up . The main factors affecting ozonation performance were pH, the nature and concentration of oxidisable organics, ozone dose, competition between the target compound and biodegradable by-products, the presence of oxidant scavengers, and the efficiency of ozone mass transfer . The formation of toxic or recalcitrant by-products has been found to occur in some cases, necessitating knowledge of wastewater constituents and trials on a site-by-site basis.

Water Res, 2001 May, 35(7), 1665 - 74
Aerobic biodegradation of an oxygenates mixture: ETBE, MTBE and TAME in an upflow fixed-bed reactor; Kharoune M et al.; Aerobic degradation of ethyl tert-butyl ether (ETBE), Methyl tert-butyl ether (MTBE) and tert-amyl methyl ether (TAME), as tertiary-substrates, was studied in a continuous upflow fixed-bed reactor (UFBR) using an external oxygenator and sintered glass rings as biomass carriers . The UFBR has been shown to be an effective system for the simultaneous and continuous long-term degradation of the three-oxygenates mixture as sole source of carbon and energy . Therefore, the oxygenates feed concentration must be related in conjunction with the hydraulic retention time "HRT" and vice versa . The permissible feed concentration of both MTBE and TAME to achieve more than 99% removal efficiency is about 80 mg L-1 at a constant HRT of 24 h . The same performance can be obtained if the HRT kept at a value equal or above to 15 h for a feed concentration of about 80 mg L-1 of both MTBE and TAME . However, the ETBE removal efficiency was always greater than 99% whatever the ETBE concentration feed (between 10 and 100 mg L-1 at a constant HRT of 24 h) and the HRT (between 24 and 13 h at a constant concentration feed of about 80 mg L-1) tested in this study . The highest ETBE, MTBE and TAME removal rates achieved throughout the UFBR runs, with efficiency better than 99%, were 140 +/- 5, 132 +/- 2 and 135 +/- 2 mg L-1 d-1, respectively . No metabolic intermediates including tert-butyl alcohol (TBA), tert-butyl formate (TBF) and tert-amyl alcohol (TAA) were detected in the effluent during all the reactor runs . Furthermore, based on the chemical oxygen demand balance, all the removed oxygenates were completely metabolized . The results of this study suggest that the higher resistance to biodegradation exhibited by the MTBE and the TAME is probably due to the steric hindrance for the attacking enzyme(s); and the major limiting step to the oxygenate degradation maybe the accessibility and the cleavage of the ether bond, but not the assimilation of their major metabolites such as TBA, TBF and TAA . These results were concomitant with the batch tests using the reactor's immobilized biomass as inoculum.

J Biomed Mater Res, 2001 May 1, 58(3), 302 - 7
Biodegradation of polyether polyurethane inner insulation in bipolar pacemaker leads; Wiggins MJ et al.; Several bipolar coaxial pacemaker leads, composed of an outer silicone rubber insulation and an inner polyether polyurethane (PEU) insulation, which were explanted due to clinical evidence of electrical dysfunction, were analyzed in this study . Optical microscopy (OM) and scanning electron microscopy (SEM) were used to determine the cause of failure . Attenuated total reflectance-Fourier transform infrared microscopy (ATR-FTIR) was used to analyze the PEU insulation for chemical degradation . In all leads, the silicone rubber outer insulation showed no signs of physical damage . Physical damage to the inner PEU insulation was the source of electrical dysfunction . Cracks through the PEU compromised the insulation between the inner and outer conductor coils in the lead . It was observed with SEM that these cracks originated on the outer surface of the inner insulation and progressed inward . ATR-FTIR analysis showed that the PEU had chemically degraded via oxidation of the ether soft segment . Furthermore, it was revealed that chemical degradation was more advanced on the outer surface of the PEU . It was hypothesized that hydrogen peroxide permeated through the outer silicone insulation and decomposed into hydroxyl radicals that caused the chemical degradation of PEU . The metal in the outer conductor coil catalyzed the decomposition of the hydrogen peroxide . Chemical degradation of the PEU could also have been catalyzed by metal ions created from the corrosion of the metal in the outer conductor coil by hydrogen peroxide . Physical damage probably occurred in regions of the leads that were subjected to a higher hydrogen peroxide concentration from inflammatory cells and high degrees and rates of strain due to intercorporeal movement, including, but not limited to, cardiac movement . Chemical degradation and physical damage probably had a synergistic affect on failure of the insulation, in that as chemical degradation proceeded, the polymer surface became brittle and more susceptible to physical damage . As physical damage proceeded, cracks propagated into the unaffected bulk, exposing it to oxidants .

Gene Ther, 2001 Apr, 8(7), 515 - 22
DNA binding chelates for nonviral gene delivery imaging; Bogdanov A Jr et al.; Noninvasive in vivo monitoring of gene delivery would provide a critically important information regarding the spatial distribution, local concentration, kinetics of removal and/or biodegradation of the expression vector . We developed a novel approach to noninvasive gene delivery imaging using heterobifunctional peptide-based chelates (PBC) bearing double-stranded DNA-binding groups and a technetium-binding amino acid motif . One of such chelates: Gly-Cys(Acm)-Gly-Cys(Acm)-Gly-Lys(4)-Lys-(N-epsilon-{4-(psoralen-8-yloxy)}butyrate)-NH(2) has been characterized and labeled with reduced (99m)Tc pertechnetate (oxotechnetate) . The psoralen moiety (a DNA binding group of PBC) allowed linking to double-stranded DNA upon short-term irradiation with the near UV range light (>320 nm) . Approximately 30-40% of added (99m)Tc-labeled PBC was nonextractable and co-eluted with a model pCMV-GFP vector during the gel-permeation chromatography . Nuclear imaging of "naked" DNA and DNA complexes with lipid-based transfection reagents ("lipoplexes") has been performed after systemic or local administration of (99m)Tc-PBC-labeled DNA in mice . Imaging results were corroborated with the biodistribution using (99m)Tc-PBC and (32)P-labeled DNA and lipoplexes . A markedly different biodistribution of (99m)Tc PBC-labeled DNA and lipoplexes was observed with the latter being rapidly trapped in the liver, spleen and lung . (99m)Tc PBC-DNA was used as an imaging tracer during in vivo transfection of B16 melanoma by local injection of "naked" (99m)Tc PBC-DNA and corresponding lipoplexes . As demonstrated by nuclear imaging, (99m)Tc PBC-DNA lipoplexes showed a slower elimination from the site of injection than (99m)Tc PBC-DNA alone . This result correlated with a higher expression of marker mRNA and green fluorescent protein as determined using RT-PCR and immunohistochemistry, respectively.

Appl Environ Microbiol, 2001 May, 67(5), 2222 - 9
Mycobacterium diversity and pyrene mineralization in petroleum-contaminated soils; Cheung PY et al.; Degradative strains of fast-growing Mycobacterium spp . are commonly isolated from polycyclic aromatic hydrocarbon (PAH)-contaminated soils . Little is known, however, about the ecology and diversity of indigenous populations of these fast-growing mycobacteria in contaminated environments . In the present study 16S rRNA genes were PCR amplified using Mycobacterium-specific primers and separated by temperature gradient gel electrophoresis (TGGE), and prominent bands were sequenced to compare the indigenous Mycobacterium community structures in four pairs of soil samples taken from heavily contaminated and less contaminated areas at four different sites . Overall, TGGE profiles obtained from heavily contaminated soils were less diverse than those from less contaminated soils . This decrease in diversity may be due to toxicity, since significantly fewer Mycobacterium phylotypes were detected in soils determined to be toxic by the Microtox assay than in nontoxic soils . Sequencing and phylogenetic analysis of prominent TGGE bands indicated that novel strains dominated the soil Mycobacterium community . Mineralization studies using {(14)C}pyrene added to four petroleum-contaminated soils, with and without the addition of the known pyrene degrader Mycobacterium sp . strain RJGII-135, indicated that inoculation increased the level of degradation in three of the four soils . Mineralization results obtained from a sterilized soil inoculated with strain RJGII-135 suggested that competition with indigenous microorganisms may be a significant factor affecting biodegradation of PAHs . Pyrene-amended soils, with and without inoculation with strain RJGII-135, experienced both increases and decreases in the population sizes of the inoculated strain and indigenous Mycobacterium populations during incubation.

Cytobios, 2001, 104(407), 139 - 43
Chronic renal failure and anterior hypophysial hormones; Milkov V et al.; Kidneys are not only organs with an excretory function but they produce their own endocrine factors which are involved in supporting homeostasis in the organism . The kidneys are the organs in which metabolism and biodegradation of many hormones take place . Together with the liver, the kidneys actively take part in the catabolism of hormones.

Bioresour Technol, 2001 Jan, 76(1), 39 - 44
Agronomic use of biotechnologically processed grape wastes; Ferrer J et al.; Grape waste was composted by biodegradation and subsequently used as an organic fertilizer for 20 day-corn . Combinations of recently compressed grape waste and hen droppings (10% w/w) were prepared to study the activating effect of hen droppings and the effect of aeration on the composting process . The final hydrogen potential (pH), %C, %N and C/N ratio, indicated an adequate development of the bioprocess . Satisfactory results were observed when the products were applied at several doses (1,000-4,000 kg/ ha) as a soil conditioner for corn seed germination in greenhouses . Only the addition of hen droppings had a significant effect (P < 0.05) on corn dry matter (14% increase) . A dose of 3000 kg/ha was considered as optimal and was used supplemented with triple superphosphate (TSP) in agronomic trials . All the treatments produced greater corn dry matter (P < 0.05) than the chemical industrial fertilizer used as a control (0.52-0.71 g/pot for the organic fertilizers vs 0.45 g/pot for the control) . Anaerobic conditions and hen droppings addition significantly produced (P < 0.05) higher corn dry matter.

Sci Total Environ, 2001 Mar 26, 269(1-3), 75 - 85
Occurrence and fate of linear and branched alkylbenzenesulfonates and their metabolites in surface waters in the Philippines; Eichhorn P et al.; Laguna de Bay in the Philippines is one of the largest freshwater lakes in Asia and is considered a primary source of drinking water, but also receives daily discharges of effluent from both domestic and industrial activities . Branched alkylbenzenesulfonates (ABS), which were banned in Europe and withdrawn from the market in the U.S . since the mid-1960s, but not in Southeast Asia, and linear alkylbenzenesulfonates (LAS) are anionic surfactants used in detergent formulations and are therefore main components of effluent discharges . The presence of both LAS and ABS in several water streams in the catchment area of Laguna de Bay was determined using liquid chromatography-mass spectrometry (LC-MS) . The concentration levels of LAS (1.2-73 and 2.2-102 microg l(-1)) and ABS (1.1-75 and 1-66 microg l(-1)) in some tributaries of Laguna de Bay and its outlet (Pasig River) to Manila Bay were assessed in December 1999 and March 2000, respectively . The LAS/ABS ratio was calculated as an indication of the extent of the distribution and fate of these surfactants in the surface water . The nearer the location to the metropolitan area of Manila, the higher the levels of LAS and ABS detected in the waters . Moreover, the extent of biodegradation was investigated by monitoring their alkyl homologue distribution and the presence of sulfophenylcarboxylate (SPC) metabolites . Similarly, differences in the levels of SPC and the homologues were apparent at the different sampling points . Presumably, even the quite recalcitrant ABS form SPCs under the conditions present in Southeast Asia . Since wastewater treatment facilities are not well established in developing countries like the Philippines, the call for the use of environmentally friendly chemicals is of even higher significance.

Chemosphere, 2001 Apr, 43(3), 377 - 83
Fate, effects and potential environmental risks of ethylene glycol: a review; Staples CA et al.; The fate, effects, and potential environmental risks of ethylene glycol (EG) in the environment were examined . EG undergoes rapid biodegradation in aerobic and anaerobic environments (approximately 100% removal of EG within 24 h to 28 days) . In air, EG reacts with photo-chemically produced hydroxyl radicals with a resulting atmospheric half-life of 2 days . Acute toxicity values (LC(50)s and EC(50)s) were generally >10,000 mg/l for fish and aquatic invertebrates . The data collectively show that EG is not persistent in air, surface water, soil, or groundwater, is practically non-toxic to aquatic organisms, and does not bioaccumulate in aquatic organisms . Potential long-term, quasi-steady state regional concentrations of EG estimated with a multi-media model for air, water, soil, and sediment were all less than predicted no effect concentrations (PNECs).

Chemosphere, 2001 Apr, 43(3), 273 - 8
Biodegradation of phenanthrene in river sediment; Yuan SY et al.; The aerobic biodegradation potential of phenanthrene (a polycyclic aromatic hydrocarbon {PAH}) in river sediment was investigated in the laboratory . Biodegradation rate constants (k1) and half-lives (t1/2) for phenanthrene (5 microg/g) in sediment samples collected at five sites along the Keelung River in densely populated northern Taiwan ranged from 0.12 to 1.13 l/day and 0.61 to 5.78 day, respectively . Higher biodegradation rate constants were noted in the absence of sediment . Two of the sediment samples were capable of biodegrading phenanthrene at initial concentrations 5-100 microg/g; lower biodegradation rates occurred at higher concentrations . Optimal biodegradation conditions were determined as 30 degreesC and pH 7.0 . Biodegradation was not significantly influenced by the addition of such carbon sources as acetate, pyruvate, and yeast extract, but was significantly influenced by the addition of ammonium, sulfate, and phosphate . Results show that anthracene, fluorene, and pyrene biodegradation was enhanced by the presence of phenanthrene, but that phenanthrene treatment did not induce benzo{a}pyrene biodegradation during a 12-day incubation period.

ISA Trans, 2001, 40(1), 41 - 56
Experimental design of an optimal phase duration control strategy used in batch biological wastewater treatment; Pavgelj NB et al.; The paper presents the design of an algorithm used in control of a sequencing batch reactor (SBR) for wastewater treatment . The algorithm is used for the on-line optimization of the batch phases duration which should be applied due to the variable input wastewater . Compared to an operation with fixed times of batch phases, this kind of a control strategy improves the treatment quality and reduces energy consumption . The designed control algorithm is based on following the course of some simple indirect process variables (i.e . redox potential, dissolved oxygen concentration and pH), and automatic recognition of the characteristic patterns in their time profile . The algorithm acts on filtered on-line signals and is based on heuristic rules . The control strategy was developed and tested on a laboratory pilot plant . To facilitate the experimentation, the pilot plant was superimposed by a computer-supported experimental environment that enabled: (i) easy access to all data (on-line signals, laboratory measurements, batch parameters) needed for the design of the algorithm, (ii) the immediate application of the algorithm designed off-line in the Matlab package also in real-time control . When testing on the pilot plant, the control strategy demonstrated good agreement between the proposed completion times and actual terminations of the desired biodegradation processes.

Chemosphere, 2001 Apr, 43(2), 207 - 15
PCB congener selective biodegradation by the white rot fungus Pleurotus ostreatus in contaminated soil; Kubatova A et al.; Six strains of white rot fungi were tested for their biodegradation ability of low chlorinated polychlorinated biphenyl (PCB) commercial mixture (Delor 103) in real soil system . Phanerochaete chrysosporium and Trametes versicolor did not show any ability to degrade PCBs in soil . On the contrary, four strains of Pleurotus ostreatus were able to remove about 40% of Delor 103 in two months . All P . ostreatus strains decomposed PCBs selectively with the preference for congeners with chlorine atoms in ortho > meta > para position . Degradation efficiency decreased with increasing number of chlorination.

FEMS Microbiol Ecol, 2001 Apr, 35(2), 145 - 150
Molecular characterization of sulfate-reducing bacteria in anaerobic hydrocarbon-degrading consortia and pure cultures using the dissimilatory sulfite reductase (dsrAB) genes; Perez-Jimenez JR et al.; The characterization of sulfate-reducing bacteria (SRBs) is presented using the dissimilatory sulfite reductase (dsrAB) gene from various samples capable of mineralizing petroleum components . These samples include several novel, sulfidogenic pure cultures which degrade alkanes, toluene, and tribromophenol . Additionally, we have sulfidogenic consortia which re-mineralize benzene, naphthalene, 2-methylnaphthalene, and phenanthrene as a sole carbon source . In this study, 22 new dsrAB genes were cloned and sequenced . The dsrAB genes from our pollutant-degrading cultures or consortia were distributed among known SRBs and previously described dsrAB environmental clones, suggesting that many biodegradative SRBs are phylogenetically distinct and geographically wide spread . Specifically, the same dsrAB gene was discovered in independently established consortia capable of benzene, phenanthrene, and methylnaphthalene degradation, indicating that this particular SRB may be a key player in anaerobic degradation of hydrocarbons in the environment.

J Contam Hydrol, 2001 Mar, 48(1-2), 121 - 49
Stochastic-convective transport with nonlinear reaction and mixing: application to intermediate-scale experiments in aerobic biodegradation in saturated porous media; Ginn TR et al.; Aerobic biodegradation of benzoate by Pseudomonas cepacia sp . in a saturated heterogeneous porous medium was simulated using the stochastic-convective reaction (SCR) approach . A laboratory flow cell was randomly packed with low permeability silt-size inclusions in a high permeability sand matrix . In the SCR upscaling approach, the characteristics of the flow field are determined by the breakthrough of a conservative tracer . Spatial information on the actual location of the heterogeneities is not used . The mass balance equations governing the nonlinear and multicomponent reactive transport are recast in terms of reactive transports in each of a finite number of discrete streamtubes . The streamtube ensemble members represent transport via a steady constant average velocity per streamtube and a conventional Fickian dispersion term, and their contributions to the observed breakthroughs are determined by flux-averaging the streamtube solute concentrations . The resulting simulations were compared to those from a high-resolution deterministic simulation of the reactive transport, and to alternative ensemble representations involving (i) effective Fickian travel time distribution function, (ii) purely convective streamtube transport, and (iii) streamtube ensemble subset simulations . The results of the SCR simulation compare favorably to that of a sophisticated high-resolution deterministic approach.

Environ Pollut, 2001, 112(3), 515 - 9
Influence of oil contamination levels on hydrocarbon biodegradation in sandy sediment; Del'Arco JP et al.; The influence of oil concentration on hydrocarbon biodegradation in a sandy sediment was studied in polyvinyl chloride reactors (0.45 x 0.28 x 0.31 m) containing 76.8 kg of beach sand in natura, where the upper layer was artificially contaminated with petroleum . The oil-degrading microorganisms used consisted of a mixed culture named ND, obtained from landfarming and associated with indigenous microorganisms . On the 28th day of the process, the degradation in reactors containing sandy sediment contaminated with light Arabian oil and presenting an initial oil content of 14, 21 or 28 g kg-1 reached the following levels (%): 33.7, 32.9 and 28.9 for oil and grease; up to 88.3, 35.3 and 13.0 for C14-C26 n-alkanes; and 100, 61.3 and 59.4 for pristane, respectively . Phytane removal (37.1%) was only detected in the reactor contaminated with the lowest oil concentration studied . These results, together with the expressive bacterial growth observed (from 10(6) to 10(11) cfu g-1) give strong support to the argument that biodegradation was the dominant component of the remediation process . Susceptibility to biodegradation was inversely proportional to increasing oil contamination . The degradation of branched alkane: pristane was not repressed by the presence of n-alkanes.

Biotechnol Bioeng, 2000-2001, 71(4), 274 - 85
Modeling the kinetics of vinyl chloride cometabolism by an ethane-grown Pseudomonas sp; Verce MF et al.; Pseudomonas sp strain EA1 was isolated under aerobic conditions using ethane as the sole organic carbon and electron donor source, with an observed yield of 0.99 mg total suspended solids/mg ethane (0.85 mg volatile suspended solids / mg ethane) and a maximum specific growth rate of 0.015 d(-1) . When grown on ethane, EA1 cometabolizes vinyl chloride (VC) at a maximum rate of 0.350 micromol/mg volatile suspended solids/d and with a half saturation constant of 0.62 microM VC . The rate of VC use by EA1 is twice as high when ethane is also provided, even though consumption of ethane is almost completely inhibited until VC is consumed . The presence of ethane also reduces the total amount of VC cometabolized . A model was developed that adequately describes the batch kinetics of VC cometabolism in the presence and absence of ethane, as well as ethane metabolism in the presence and absence of VC . Terms are included that increase the initial rate of VC use in the presence of ethane (according to the ratio of initial ethane concentration to the half saturation coefficient) but decrease the total amount of VC cometabolized . Parameter estimates for the model were obtained using a step-wise experimental approach, with varying initial concentrations of VC and ethane . Strain EA1 completely dechlorinates VC in the presence and absence of ethane . Measurements of soluble chemical oxygen demand indicate that approximately 50% of the VC consumed is mineralized, with the balance released as soluble, nonchlorinated products . Ethene is not used as a substrate by EA1 but it does inhibit ethane metabolism and VC cometabolism . In mixtures containing all three compounds, more VC is degraded and at a faster rate compared to VC plus ethene . The results suggest that ethane-enhanced biodegradation of VC may contribute to VC removal at the aerobic fringe of groundwater plumes undergoing reductive dechlorination.

Anal Chem, 2001 Mar 1, 73(5), 864 - 9
Time-of-flight mass spectrometric analysis of high-molecular-weight alkanes in crude oil by silver nitrate chemical ionization after laser desorption; Dutta TK et al.; Time-of-flight mass spectrometry was used for the first time to analyze the hydrocarbons in crude oil . Alkanes in the saturated fraction of a crude oil sample were chemically ionized by the laser desorption of silver nitrate, and the silver-attached C24-C60 alkanes were resolved with mass accuracy below 7 ppm . This technique was used to evaluate the biodegradation of aliphatic hydrocarbons and cycloalkanes by oil-degrading microorganisms resident in seawater . It is shown that the aliphatic hydrocarbons were degraded in the range of 60-80%, while the mono-, di-, tri-, tetra-, and pentacycloalkanes were degraded in the range of 40-55, 20-30, 10-16, 5-9, and <5%, respectively . Its high sensitivity and speed of application could result in an analysis by laser desorption silver chemical ionization time-of-flight mass spectrometry being the method of choice for determining high-molecular-weight hydrocarbons in various petroleum products.

Ground Water, 2001 Mar-Apr, 39(2), 276 - 82
Influence of transient flow on contaminant biodegradation; Schirmer M et al.; The rate of biodegradation in contaminated aquifers depends to a large extent on dispersive mixing processes that are now generally accepted to result from spatial variations in the velocity field . It has been shown, however, that transient flow fields can also contribute to dispersive mixing . The influence of transient flow on biodegrading contaminants is particularly important since it can enhance mixing with electron acceptors, further promoting the reactive process . Using numerical simulations, the effect of transient flow on the behavior of a biodegradable contaminant is evaluated here both with respect to the development of apparently large horizontal transverse dispersion and also with respect to enhanced mixing between the substrate (electron donor) and electron acceptor . The numerical model BIO3D, which solves for advective-dispersive transport coupled with Monod-type biodegradation of substrates in the presence of an electron acceptor, was used for the simulations . The model was applied in a two-dimensional plan view mode considering a single substrate . Transient flow fields were found to yield larger apparent transverse dispersion because the longitudinal dispersivity also acts transverse to the mean flow direction . In the reactive case, the transient flow field increases substrate-oxygen mixing, which in turn enhances the overall rate of biodegradation . The results suggest that in the case of moderate changes of flow directions, a steady-state flow field can be justified, thereby avoiding the higher computational costs of a fully transient simulation . The use of a higher transverse horizontal dispersivity in a steady flow field can, under these conditions, adequately forecast plume development.

Ground Water, 2001 Mar-Apr, 39(2), 192 - 202
Natural attenuation of volatile organic compounds (VOCs) in the leachate plume of a municipal landfill: using alkylbenzenes as process probes; Eganhouse RP et al.; More than 70 individual VOCs were identified in the leachate plume of a closed municipal landfill . Concentrations were low when compared with data published for other landfills, and total VOCs accounted for less than 0.1% of the total dissolved organic carbon . The VOC concentrations in the core of the anoxic leachate plume are variable, but in all cases they were found to be near or below detection limits within 200 m of the landfill . In contrast to the VOCs, the distributions of chloride ion, a conservative tracer, and nonvolatile dissolved organic carbon, indicate little dilution over the same distance . Thus, natural attenuation processes are effectively limiting migration of the VOC plume . The distribution of C2-3-benzenes, paired on the basis of their octanol-water partition coefficients and Henry's law constants, were systematically evaluated to assess the relative importance of volatilization, sorption, and biodegradation as attenuation mechanisms . Based on our data, biodegradation appears to be the process primarily responsible for the observed attenuation of VOCs at this site . We believe that the alkylbenzenes are powerful process probes that can and should be exploited in studies of natural attenuation in contaminated ground water systems.

J Environ Qual, 2001 Mar-Apr, 30(2), 395 - 403
Phytoremediation of aged petroleum sludge: effect of inorganic fertilizer; Hutchinson SL et al.; Phytoremediation is a promising new technology that uses higher plants to enhance biodegradation . Nutrient availability is an important factor governing the success of phytoremediation and can be regulated through the addition of fertilizer . A greenhouse study was conducted to assess the importance of nitrogen and phosphorus for the phytoremediation of petroleum sludge . Degradation of total petroleum hydrocarbons (TPH) was quantified for six fertilization rates and three vegetation treatments: bermuda grass {Cynodon dactylon (L.) Pers.}, tall fescue (Festuca arundinacea Schreb.), and an unvegetated control . During the first 6 mo of the experiment, TPH declined by an average of 49% with no significant differences between treatments . After 1 yr, TPH degradation was significantly greater in both vegetated treatments with a mean TPH reduction of 68% for bermuda, 62% for fescue, and 57% for the unvegetated control . Degradation of TPH in the fescue and bermuda treatments was significantly lower in the treatments in which no fertilizer was added or N and P were added simply to maintain plant growth compared with the higher rates of fertilization . For this short-term, greenhouse experiment, optimal remediation was obtained by fertilization that produced a C to N to P ratio of 100:2:0.2.

Mar Environ Res, 2000 Jun, 49(5), 403 - 17
Field observations on the variability of crude oil impact on indigenous hydrocarbon-degrading bacteria from sub-Antarctic intertidal sediments; Delille D et al.; Oil pollution of the oceans has been a problem ever since man began to use fossil fuels . Biodegradation by naturally occurring populations of micro-organisms is a major mechanism for the removal of petroleum from the environment . To examine the effects of crude oil pollution on intertidal bacteria, we repeated the same contamination experiments on nine different sub-Antarctic intertidal beaches using specifically built enclosures (PVC pipe, 15 cm in inner diameter and 30 cm in height) . Despite the pristine environmental conditions, significant numbers of indigenous hydrocarbon-degrading bacteria were observed in all the studied beaches . Introduction of oil into these previously oil-free environments resulted in several orders of magnitude of increase in hydrocarbon-degrading micro-organisms within a few days in some of the studied sites but has no obvious effects on two others . The physical environment of the bacterial assemblage seems to play a major role in the biodegradation capacities . After 3 months of contamination, both remaining oil concentrations and biodegradation indexes differ strongly between the different stations . Thus, chemical and biological parameters reveal a strong heterogeneity of biodegradation capacities between the different sites.

Appl Environ Microbiol, 2001 Apr, 67(4), 1970 - 4
Biodegradation of n-alkylcycloalkanes and n-alkylbenzenes via new pathways in Alcanivorax sp . strain MBIC 4326; Dutta TK et al.; The degradation of long-chain n-alkylbenzenes and n-alkylcyclohexanes by Alcanivorax sp . strain MBIC 4326 was investigated . The alkyl side chain of these compounds was mainly processed by beta-oxidation . In the degradation of n-alkylcyclohexanes, cyclohexanecarboxylic acid was formed as an intermediate . This compound was further transformed to benzoic acid via 1-cyclohexene-1-carboxylic acid.

Bioresour Technol, 2001 Apr, 77(2), 183 - 91
Molecular weight distribution of Pinus radiata kraft mill wastewater treated by anaerobic digestion; Vidal G et al.; Kraft mill is responsible for massive discharge of highly polluted effluents . The main characteristics of this effluent are high toxicity and low biodegradability due to tannin, lignin and chlorophenol compounds . The composition may vary dramatically depending, for instance, on the utilised feedstock and process . The purpose of this work was to investigate the molecular weight distribution of Pinus radiata kraft pulping wastewater treated by anaerobic digestion by using two types of anaerobic reactors: fixed bed and sludge blanket . Anaerobic sludge blanket (UASB) and anaerobic filter (AF) were operated . In both reactors, the total alkalinity ranged between 1.0 and 1.5 g CaCO3/l, while the organic load rate (OLR) was increasing during operation from 1.2 to 3.3 gCOD/l d . COD and total phenolic compounds (UV215) removal ranged between 30-50% and 13-20%, respectively, while the BOD5 removal ranged 60-90% . However only a partial biodegradation (10-43%) of tannin and lignin was observed . Results from ultrafiltration analyses indicated that the fraction with a molecular weight (MW) < 1000, COD and colour decreased after anaerobic treatment, but the total phenolic compounds increased . In the 1000 < MW < 10,000 fraction, there was no change in COD, UV215 and colour . In the > 10,000 MW fraction, colour and COD fraction increased by 14% and 5%, respectively, after anaerobic treatment . It can be concluded from this study, that treatment with UASB or AF reactors is not enough, under the conditions tested, for a large COD removal from Pinus radiata wastewater.

Life Sci, 2001 Mar 2, 68(15), 1787 - 805
Metabolic fate of 1-alkyl-2-acetyl-sn-glycero-3-phosphocholine by human spermatozoa: biosynthesis and biodegradation; Gujrati VR et al.; Human spermatozoa can synthesise 1-alkyl-2-acetyl-glycerophosphocholine (AAGPC) in small amount by acetyltransferase (AT) in absence of any stimulus, but can actively catabolise it by acetylhydrolase (HY) . Seminal plasma, on the other hand, was devoid of anabolic enzyme albeit enrich in catabolic enzyme, suggesting as an active site for biodegradation of AAGPC secreted by spermatozoa . Both, AT and HY exhibited pH-optima in range of 7.0-7.6 at which spermatozoa are maximum viable and motile . Ionophore A23187 and EGTA inhibited AT, reversibly, whereas HY was inhibited by BSA, calcium-channel blockers, and phospholipase A2-inhibitors . Effect of aging-time on ejaculates exhibited decreased AT activity with increased HY activity along with unchanged calcium content of spermatozoa . Serotonin in vitro studies showed a pro-aggregator role on agglutination of spermatozoa . Viscid/long liquefaction time ejaculates exhibited raised AT activity and calcium contents with decreased HY activity in spermatozoa and high degree of agglutination . Studies with dithiothreitol-treatment indeed helped in liquefaction but levels of both enzymes remained status quo, suggesting existence of both pathways: remodelling of membrane phospholipids and de novo synthesis of AAGPC in spermatozoa, earlier being pre-dominant . We have proposed a role of AAGPC-Serotonin-Calcium in agglutination and liquefaction of spermatozoa, a vital aspect in normal fertility.

FEMS Microbiol Lett, 2001 Mar 15, 196(2), 141 - 6
A simple (14)C-respirometric method for assessing microbial catabolic potential and contaminant bioavailability; Reid BJ et al.; This paper describes the validation and application of a simple flask-based (14)C-respirometer system designed to assess mineralisation of (14)C-labelled substrates under defined conditions . Validation of this respirometer system indicated stoichiometric CO(2) trapping up to a maximum of 400 micromol of CO(2) (in a single trap) . Polycyclic aromatic hydrocarbon (PAH)-degrading bacteria were used to measure growth-linked biodegradation of {(14)C}naphthalene to (14)CO(2) . A (14)C activity balance of 101.7+/-8.9% (n=6), after 74 h incubation time and 10 respirometer-opening events, indicated the suitability of the system for monitoring substrate mineralisation . This respirometric apparatus was then successfully applied to assess: (i) the PAH catabolism of microbes in a field contaminated soil, where naphthalene and phenanthrene were rapidly mineralised and (ii) soil-associated organic contaminant bioavailability, where increased soil-phenanthrene contact time resulted in a reduction in phenanthrene mineralisation in the soil . The described respirometer system differs from existing respirometer systems in that the CO(2) trap can be removed and replaced quickly and easily . The system is efficient, reproducible, adaptable to many situations, easy to construct and simple to use, it therefore affords advantages over existing systems.

Biochim Biophys Acta, 2001 Mar 9, 1546(1), 107 - 13
Expression of Pleurotus eryngii aryl-alcohol oxidase in Aspergillus nidulans: purification and characterization of the recombinant enzyme; Varela E et al.; Aryl-alcohol oxidase (AAO) is an extracellular flavoenzyme involved in lignin biodegradation by some white-rot fungi . The enzyme catalyzes the extracellular oxidation of aromatic alcohols to the corresponding aldehydes . The electron acceptor is molecular oxygen yielding H(2)O(2) as the product . Herein we describe, for the first time, the expression of AAO from Pleurotus eryngii in the ascomycete Aspergillus nidulans . The activity of the recombinant enzyme in A . nidulans cultures is much higher than found in the extracellular fluid of P . eryngii . The recombinant enzyme showed the same molecular mass, pI and catalytic properties as that of the mature protein secreted by P . eryngii . The enzymic properties are also similar to those reported from other Pleurotus and Bjerkandera species.

J Biomed Mater Res, 2001 Jun 5, 55(3), 304 - 12
Synthesis and characterization of macroporous chitosan/calcium phosphate composite scaffolds for tissue engineering; Zhang Y et al.; Chitosan scaffolds reinforced by beta-tricalcium phosphate (beta-TCP) and calcium phosphate invert glass were fabricated with a low-cost, bioclean freeze-drying technique via thermally induced phase separation . The microstructure, mechanical performance, biodegradation, and bioactivity of the scaffolds were studied . The composite scaffolds were macroporous, and the pore structures of the scaffolds with beta-TCP and the glass appeared very different . Both the compressive modulus and yield strength of the scaffolds were greatly improved, and reinforced microstructures were achieved . The bioactivity tests showed a continuous decrease in both Ca and P concentrations of a simulated body fluid (SBF) after the scaffolds with beta-TCP were immersed in the SBF for more than 20 h, which suggests that an apatite layer might be formed on the scaffolds . However, the same was not observed for the pure chitosan scaffolds or the scaffolds incorporated with the glass . This was further confirmed by micrographs from scanning electron microscopy . This study suggests that the desirable pore structure, biodegradation rate, and bioactivity of the composite scaffolds might be achieved through controlling the ratio of chitosan and calcium phosphates or beta-TCP and the glass .

Biotechnol Bioeng, 2001 Apr 5, 73(1), 12 - 24
Evaluation of the interaction between biodegradation and sorption of phenanthrene in soil-slurry systems; Woo SH et al.; This work develops and utilizes a non-steady-state model for evaluating the interactions between sorption and biodegradation of hydrophobic organic compounds in soil-slurry systems . The model includes sorption/desorption of a target compound, its utilization by microorganisms as a primary substrate existing in the dissolved phase, and/or the sorbed phase in biomass and soil, oxygen transfer, and oxygen utilization as an electron acceptor . Biodegradation tests with phenanthrene were conducted in liquid and soil-slurry systems . The soil-slurry tests were performed with very different mass transfer rates: fast mass transfer in a flask test at 150 rpm, and slow mass transfer in a roller-bottle test at 2 rpm . The results of liquid tests indicate that biodegradation of the soil-soluble organic fraction did not significantly enhance the biodegradation rate . In the slurry tests, phenanthrene was degraded more rapidly than in liquid tests, but at a similar rate in both slurry systems . Modeling analyses with several hypotheses indicate that a model without biodegradation of compound sorbed to the soil was not able to account for the rapid degradation of phenanthrene, particularly in the roller-bottle slurry test . The model with sorbed-phase biodegradation and the same biokinetic parameters, but unique mass transfer coefficients, simulated the experimental data in both slurry tests most successfully . Reduced mass transfer resistance to bacteria attached to the soil is the most likely phenomenon accounting for rapid sorbed-phase biodegradation .

Zentralbl Chir, 2001 Feb, 126(2), 151 - 5; discussion 155-6
{Biodegradation of a PTFE prosthesis}; Flessenkamper I et al.; Processes of biodegradation of PTFE--as they were not seen before for this type of graft--are demonstrated by clinical examples . As it is possible to subsume these results to regularly described processes of incorporation of alloplastic material, it is to be expected that there will be more cases than those observed by us up to now.

APMIS, 2000 Dec, 108(12), 838 - 46
Characterisation of the affinity of different anabolics and synthetic hormones to the human androgen receptor, human sex hormone binding globulin and to the bovine progestin receptor; Bauer ER et al.; For the steroidal growth promoters trenbolone acetate (TBA) and melengestrol acetate (MGA) neither the complete spectrum of biological activities nor the potential endocrine disrupting activity of their excreted metabolites in the environment is fully understood . The potency of these substances in {3H}dihydrotestosterone ({3H}-DHT) displacement from the recombinant human androgen receptor (rhAR) and from human sex-hormone binding globulin (hSHBG) was evaluated . In addition, the potency for {3H}-ORG2058 displacement from the bovine uterine progestin receptor (bPR) was tested . For comparison, different anabolics and synthetic hormones were also tested for their binding affinities . For 17beta-trenbolone (17beta-TbOH), the active compound after TBA administration, an affinity the rhAR similar to dihydrotestosterone (DHT) and a slightly higher affinity to the bPR than progesterone were demonstrated . The affinity of the two major metabolites, 17alpha-trenbolone and trendione, was reduced to less than 5% of the 17beta-TbOH-value . The affinity of these three compounds and of MGA to the hSHBG was much lower compared with DHT . MGA showed a 5.3-fold higher affinity than progesterone to the bPR but only a weak affinity to the rhAR . The major MGA metabolites have an affinity to the bPR between 85% and 28% of the affinity of progesterone . In consequence, MGA and TBA metabolites may be hormonally active substances, which will be present in edible tissues and in manure . We conclude that detailed investigations on biodegradation, distribution and bio-efficacy of these substances are necessary.

Vestn Ross Akad Med Nauk, 2000, (10), 24 - 7
{Rapid indication of microbiological damage and biodegradation of structural materials in space vehicles}; Byianov VV et al.; The study was undertaken to design a kit of indicators for rapid detection and group identification of microbes causing biological damages to the materials . Indication is accomplished by dropwise colorimetric reaction for which modified chromatographic materials serve as substrates . Reactions are made by the indicators whose design allows reagents and samples to be measured on board space vehicles . The designed kit of indicators detects microorganisms, biodegrade products, and identifies them by groups: vegetative or spore-forming bacteria, and lower fungi . The paper considers the characteristics of colorimetric reactions and an algorithm of group identification of microbes by the respective combination of positive and negative results of the reactions . It also presents data on the sensitivity levels of tests provided by the kit, which were obtained from laboratory and field ground tests.

J Biotechnol, 2001 Mar 30, 86(2), 87 - 95
Biodegradation of polyesters containing aromatic constituents; Muller RJ et al.; Polymers, which undergo a controlled biological degradation by micro-organisms came to remarkable interest during the last years . Composting for instance could so be established as an alternative waste management system for parts of the plastic waste . Within this group of innovative polymer, polyesters play a predominant role, due to their potentially hydrolyzable ester bonds . While aromatic polyesters such as poly(ethylene terephthalate) exhibit excellent material properties but proved to be almost resistant to microbial attack, many aliphatic polyesters turned out to be biodegradable but lack in properties, which are important for application . To combine good material properties with biodegradability, aliphatic-aromatic copolyesters have been developed as biodegradable polymers for many years . This article reviews the attempts to combine aromatic and aliphatic structures in biodegradable plastics and work, which has been done to evaluate the degradation behaviour and environmental safety of biodegradable polyesters, containing aromatic constituents.

Environ Microbiol, 2000 Feb, 2(1), 91 - 8
Field-scale remediation of atrazine-contaminated soil using recombinant Escherichia coli expressing atrazine chlorohydrolase; Strong LC et al.; We performed the first field-scale atrazine remediation study in the United States using chemically killed, recombinant organisms . This field study compared biostimulation methods for enhancing atrazine degradation with a novel bioaugmentation protocol using a killed and stabilized whole-cell suspension of recombinant Escherichia coli engineered to overproduce atrazine chlorohyrolase, AtzA . AtzA dechlorinates atrazine, producing non-toxic and non-phytotoxic hydroxyatrazine . Soil contaminated by an accidental spill of atrazine (up to 29,000 p.p.m.) supported significant populations of indigenous microorganisms capable of atrazine catabolism . Laboratory experiments indicated that supplementing soil with carbon inhibited atrazine biodegradation, but inorganic phosphate stimulated atrazine biodegradation . A subsequent field-scale study consisting of nine (0.75m3) treatment plots was designed to test four treatment protocols in triplicate . Control plots contained moistened soil; biostimulation plots received 300p.p.m . phosphate; bioaugmentation plots received 0.5% (w/w) killed, recombinant E . coli cells encapsulating AtzA; and combination plots received phosphate plus the enzyme-containing cells . After 8 weeks, atrazine levels declined 52% in plots containing killed recombinant E . coli cells, and 77% in combination plots . In contrast, atrazine levels in control and biostimulation plots did not decline significantly . These data indicate that genetically engineered bacteria overexpressing catabolic genes significantly increased degradation in this soil heavily contaminated with atrazine.

J Hazard Mater, 2001 Apr 20, 82(3), 275 - 89
Evaluation of natural attenuation rate at a gasoline spill site; Kao CM et al.; Contamination of groundwater by gasoline and other petroleum-derived hydrocarbons released from underground storage tanks (USTs) is a serious and widespread environmental problem . Natural attenuation is a passive remedial approach that depends upon natural processes to degrade and dissipate contaminants in soil and groundwater . Currently, in situ column technique, microcosm, and computer modeling have been applied for the natural attenuation rate calculation . However, the subsurface heterogeneity reduces the applicability of these techniques . In this study, a mass flux approach was used to calculate the contaminant mass reduction and field-scale decay rate at a gasoline spill site . The mass flux technique is a simplified mass balance procedure, which is accomplished using the differences in total contaminant mass flux across two cross-sections of the contaminant plume . The mass flux calculation shows that up to 87% of the dissolved total benzene, toluene, ethylbenzene, and xylene (BTEX) isomers removal was observed via natural attenuation at this site . The efficiency of natural biodegradation was evaluated by the in situ tracer method, and the first-order decay model was applied for the natural attenuation/biodegradation rate calculation . Results reveal that natural biodegradation was the major cause of the BTEX mass reduction among the natural attenuation processes, and approximately 88% of the BTEX removal was due to the natural biodegradation process . The calculated total BTEX first-order attenuation and biodegradation rates were 0.036 and 0.025% per day, respectively . Results suggest that the natural attenuation mechanisms can effectively contain the plume, and the mass flux method is useful in assessing the occurrence and efficiency of the natural attenuation process.

Biochim Biophys Acta, 2001 Feb 26, 1530(2-3), 134 - 45
Liposomes as sustained release system for human interferon-gamma: biopharmaceutical aspects; Van Slooten ML et al.; Interferon-gamma (IFNgamma) has proven to be a promising adjuvant in vaccines against cancer and infectious diseases . However, due to its rapid biodegradation and clearance, its efficacy is severely reduced . Liposomal association might prolong the residence time of IFNgamma, but no efforts have been made to optimize the biopharmaceutical characteristics of liposomal IFNgamma for its application in therapy or as vaccine immunoadjuvant . In the present study, various liposomal formulations of recombinant human IFNgamma (hIFNgamma), differing in lipid composition, were prepared via the film hydration method and characterized in vitro regarding association efficiency and bioactivity, and in vivo regarding cytokine release kinetics after subcutaneous (s.c.) administration into mice . Human IFNgamma can be formulated in large, multilamellar liposomes with high association efficiency (>80%) and preservation of bioactivity . A critical parameter is the inclusion of negatively charged phospholipids to obtain a high liposome association efficiency, which is dominated by electrostatic interactions . The fraction of externally adsorbed protein compared to the total associated protein can be minimized from 74+/-9% to 8+/-3% by increasing the ionic strength of the dispersion medium . After injection of free (125)I-hIFNgamma, the radiolabel was detectable up to 48 h at the injection site . Liposomal encapsulation of (125)I-hIFNgamma increased the local area under the curve 4-fold, and the presence of the radiolabeled hIFNgamma at the injection site was prolonged to 7 days . The release kinetics and overall residence time of the cytokine at the s.c . administration site was influenced by depletion of the externally adsorbed IFNgamma, reducing the initial burst release . Increasing the rigidity of the liposome bilayer also resulted in a more pronounced reduction of the burst release and a 19-fold increase in the residence time of the protein at the s.c . administration site, compared to the free cytokine . As adjuvanticity of liposomal IFNgamma may strongly depend on the release kinetics of cytokines in vivo, the findings in this paper may contribute to a rational design of liposomal-cytokine adjuvants in vaccines against cancer and infectious diseases.

Nature, 2001 Feb 15, 409(6822), 801 - 4
Evidence for non-selective preservation of organic matter in sinking marine particles; Hedges JI et al.; The sinking of particulate organic matter from ocean surface waters transports carbon to the ocean interior, where almost all is then recycled . The unrecycled fraction of this organic matter can become buried in ocean sediments, thus sequestering carbon and so influencing atmospheric carbon dioxide concentrations . The processes controlling the extensive biodegradation of sinking particles remain unclear, partly because of the difficulty in resolving the composition of the residual organic matter at depth with existing chromatographic techniques . Here, using solid-state 13C NMR spectroscopy, we characterize the chemical structure of organic carbon in both surface plankton and sinking particulate matter from the Pacific Ocean and the Arabian Sea . We found that minimal changes occur in bulk organic composition, despite extensive (>98%) biodegradation, and that amino-acid-like material predominates throughout the water column in both regions . The compositional similarity between phytoplankton biomass and the small remnant of organic matter reaching the ocean interior indicates that the formation of unusual biochemicals, either by chemical recombination or microbial biosynthesis, is not the main process controlling the preservation of particulate organic carbon within the water column at these two sites . We suggest instead that organic matter might be protected from degradation by the inorganic matrix of sinking particles.

Appl Microbiol Biotechnol, 2001 Jan, 55(1), 101 - 7
Biodegradation of sulfanilic acid by Pseudomonas paucimobilis; Perei K et al.; An aerobic bacterium, isolated from a contaminated site, was able to degrade sulfanilic acid (4-aminobenzenesulfonic acid) and was identified as Pseudomonas paucimobilis . The isolate could grow on sulfanilic acid (SA) as its sole carbon and nitrogen source and metabolized the target compound to biomass . The bioconversion capacity depended on the sulfanilic acid concentration; greater than 98% elimination of the hazardous compound was achieved at low (10 mM) sulfanilic acid concentration, and the yield was greater than 70% at 50 mM concentration of the contaminant . The maximum conversion rate was 1.5 mmol sulfanilic acid/h per mg wet cells at 30 degrees C . Ca-alginate-phytagel proved a good matrix for immobilization of P . paucimobilis, with essentially unaltered biodegradation activity . Removal of sulfanilic acid from contaminated industrial waste water was demonstrated . SDS-PAGE analysis of the crude extract revealed novel proteins appearing upon induction with sulfanilic acid and related compounds, which indicated alternative degradation mechanisms involving various inducible enzymes.

J Econ Entomol, 2001 Feb, 94(1), 145 - 9
Impact of four insecticides on Japanese beetle (Coleoptera: Scarabaeidae) egg predators and white grubs in turfgrass; Zenger JT et al.; Field experiments were conducted to measure the effects of four commonly used turfgrass insecticides (isofenphos, diazinon, imidacloprid, halofenozide) on white grubs (Coleoptera: Scarabaeidae) and ant predators of white grub eggs . Ant populations were measured over time with canned tuna, whereas predation by the ants was measured with artificially placed Japanese beetle, Popillia japonica Newman, eggs . The effectiveness of each insecticide at controlling Japanese beetle grubs, when applied at different times during the growing season, also was measured . Isofenphos and diazinon significantly reduced both ant numbers and white grub egg predation, whereas imidacloprid and one halofenozide treatment did not significantly impact either measurement . A second halofenozide treatment significantly reduced white grub egg predation . Isofenphos and diazinon were ineffective at controlling Japanese beetle grubs when applied in June but were highly efficacious when applied in August . Evidence of enhanced biodegradation was found in plots that received both June and August applications of diazinon . Both June and August applications of imidacloprid and halofenozide provided good control of white grubs.

Water Res, 2001 Feb, 35(2), 425 - 32
Colour removal from a simulated dye wastewater using a two-phase anaerobic packed bed reactor; Mahdavi Talarposhti A et al.; In recent years, rapid technological advances in the textile and dyeing industry have yielded benefits to society but have also generated new and significant environmental problems . The treatment alternatives applicable for the removal of colour vary, depending upon the type of dye wastewater . A synthetic, simulated mixed dye waste (Basic Yellow 28, Basic Yellow 21, Basic Red 18.1, Basic Violet Red 16, Basic Red 46, Basic Blue 16, Basic Blue 41) representing a known waste from a fibre production factory, was investigated . The biological process of anaerobic digestion has been recognised as a simple and energy-efficient means of treating and stabilising a wide range of organic industrial wastewaters . This study sets out to demonstrate the effect of different loading rates, dye concentrations and hydraulic retention times (HRTs) on colour removal efficiency under mesophilic anaerobic conditions . The reactor was operated under mesophilic conditions at different organic loading rates (OLRs) and HRTs for nine months . The results of this study show that a 2-stage mesophilic anaerobic up-flow packed bed reactor can remove up to 90% of the colour from a mixed cationic dye containing 1000 mg/l of dye . Colour removal efficiency falls as the influent dye concentration increases, but rises with increased hydraulic retention time and increased organic loading . The primary colour removal mechanism was one of biosorption with subsequent biodegradation . Acetoclastic methanogens were moderately inhibited at low organic loading rates of 0.25 kg COD/m3 d, at which level, acidogenesis and acetogenesis appeared to be unaffected . Inhibition of acidogenesis became marked at higher OLRs (1 kg COD/m3 d) and when the HRT was reduced from 5 to 3 days.

Ecotoxicology, 2001 Feb, 10(1), 35 - 50
Polycyclic aromatic hydrocarbon-polluted dredged peat sediments and earthworms: a mutual interference; Eijsackers H et al.; In lowland areas of the Netherlands, any peat sediments will gradually become enriched with anthropogenically derived Polycyclic Aromatic Hydrocarbons . Due to Dutch policy standards these (anaerobic) sediments are not allowed to be dredged and placed onto land . Under aerobic conditions, however, biodegradation of PAH is greatly enhanced . This degradation is further stimulated by colonisation of the sediments by earthworms . Laboratory experiments show that although earthworms do not avoid PAH-contaminated sediment, their burrowing-activity is reduced . Furthermore, these sediments have no significant ecotoxicological impacts on earthworms . Experimental introduction of earthworms into PAH-contaminated OECD-soil will result in a decrease in overall PAH content . In field surveys no significant differences in earthworm numbers between locations with fresh and old sediment could be found . It is concluded that dredging of PAH-contaminated sediment poses a very limited environmental threat, and that putting these sediments on land will improve PAH-biodegradation, partly through the colonisation by and activities of earthworms.

Nucleic Acids Res, 2001 Mar 1, 29(5), 1097 - 106
Radical SAM, a novel protein superfamily linking unresolved steps in familiar biosynthetic pathways with radical mechanisms: functional characterization using new analysis and information visualization methods; Sofia HJ et al.; A novel protein superfamily with over 600 members was discovered by iterative profile searches and analyzed with powerful bioinformatics and information visualization methods . Evidence exists that these proteins generate a radical species by reductive cleavage of S:-adenosylmethionine (SAM) through an unusual Fe-S center . The superfamily (named here Radical SAM) provides evidence that radical-based catalysis is important in a number of previously well- studied but unresolved biochemical pathways and reflects an ancient conserved mechanistic approach to difficult chemistries . Radical SAM proteins catalyze diverse reactions, including unusual methylations, isomerization, sulfur insertion, ring formation, anaerobic oxidation and protein radical formation . They function in DNA precursor, vitamin, cofactor, antibiotic and herbicide biosynthesis and in biodegradation pathways . One eukaryotic member is interferon-inducible and is considered a candidate drug target for osteoporosis; another is observed to bind the neuronal Cdk5 activator protein . Five defining members not previously recognized as homologs are lysine 2,3-aminomutase, biotin synthase, lipoic acid synthase and the activating enzymes for pyruvate formate-lyase and anaerobic ribonucleotide reductase . Two functional predictions for unknown proteins are made based on integrating other data types such as motif, domain, operon and biochemical pathway into an organized view of similarity relationships.

Ecotoxicol Environ Saf, 2001 Mar, 48(3), 311 - 20
Biodegradability of metronidazole, olaquindox, and tylosin and formation of tylosin degradation products in aerobic soil--manure slurries; Ingerslev F et al.; The use of veterinary drugs (primarily antibiotics) in animal husbandry harbors the risk that these compounds end up in the farmland when manure is used as fertilizer . The biodegradability of three compounds, olaquindox (OLA), metronidazole (MET), and tylosin (TYL), was simulated in soil--manure slurries with 50 g of soil per liter . Supplemental batch sorption tests revealed that insignificant amounts of OLA and MET were located in the soil phase, whereas only 0.1 to 10% of the added amounts of TYL remained in the liquid phase . This may reduce the bioavailability and thus biodegradation rates of TYL . Unidentified metabolites of OLA and TYL and four known TYL metabolites were detected using HPLC . However, none of these substances were seen to persist in the biodegradation experiments, indicating that OLA and TYL most likely were mineralized in the experiments . Neither the use of sandy or clayey soil nor the use of 0, 1, or 10% (V/V) of manure added to these soils had a significant effect on the degradation rates . Degradation half-lives for the primary degradation were 3.3--8.1 days for TYL, 5.8--8.8 days for OLA, and 13.1--26.9 days for MET . Based on comparisons of results obtained with the benchmark chemical aniline and degradation half-lives of this compound in nature, it was assessed that results obtained with the current test method slightly overestimate real-world biodegradation rates .

Adv Biochem Eng Biotechnol, 2001, 71, 293 - 325
Microbial degradation of polyesters; Jendrossek D; Polyesters, such as microbially produced poly{(R)-3-hydroxybutyric acid} {poly(3HB)}, other poly{(R)-hydroxyalkanoic acids} {poly(HA)} and related biosynthetic or chemosynthetic polyesters are a class of polymers that have potential applications as thermoplastic elastomers . In contrast to poly(ethylene) and similar polymers with saturated, non-functionalized carbon backbones, poly(HA) can be biodegraded to water, methane, and/or carbon dioxide . This review provides an overview of the microbiology, biochemistry and molecular biology of poly(HA) biodegradation . In particular, the properties of extracellular and intracellular poly(HA) hydrolyzing enzymes {poly(HA) depolymerases} are described.

Biol Pharm Bull, 2001 Feb, 24(2), 205 - 8
Biodegradation and drug release of chitosan gel beads in subcutaneous air pouches of mice; Kofuji K et al.; Chitosan (CS) gel beads were prepared in 10% amino acid solution (pH 9) and implanted into air pouches (AP) prepared subcutaneously on the dorsal surface of mice . No inflammatory response was observed, and degradation of the beads in the AP increased as their degree of deacetylation decreased . Degradation could be altered by changing the nature of the CS or by increasing the CS concentration . The release of prednisolone (PS) in vivo from CS gel beads was similar to the release in vitro . When a suspension of PS was injected into the AP, the PS had almost completely disappeared 24 h after injection . Retention of PS in the AP was not increased by using a viscous CS solution . Alginate (Alg) gel beads, which were not degraded, released PS slowly into the AP over 3d . The in vitro release profile of PS using 1% CS (deacetylation: 70% (7B) and 80% (8B)) and 1.5% CS (deacetylation: 90% (9B)) gel beads was similar to that with Alg gel beads . However, the in vivo release of PS was affected by the degradability of the gel beads . CS7B and 8B (1%) gel beads had released PS into the AP earlier than 3 d according to their rate of degradation . CS9B (1.5%) gel beads were not degraded after 3 d and went on to release PS into the AP for 3 d similar to the release profile of Alg gel beads . CS9B (2%) gel beads were also not degraded after 3 d and the release of PS from these beads into the AP was sustained; 76% and 27% of administered PS remained in the gel beads after 1 and 3 d, respectively . Therefore, degradation and drug release of CS gel beads can be controlled by changing the structure of the gel matrix, which appears to make these beads a promising biodegradable vehicle for sustained drug delivery.

J Biomater Sci Polym Ed, 2000, 11(9), 915 - 30
Controlled release of vascular endothelial growth factor by use of collagen hydrogels; Tabata Y et al.; In vivo profile of vascular endothelial growth factor (VEGF) release from collagen hydrogels was investigated comparing that of hydrogel degradation while angiogenesis induced by the released VEGF was assessed . Collagen sponges were chemically cross-linked with different amounts of glutaraldehyde for various time periods . When 125I-labeled collagen hydrogels incorporating VEGF were subcutaneously implanted into the back subcutis of mice, the hydrogel radioactivity decreased with time, the decrement profile depending on the cross-linking conditions . The radioactivity was retained for longer time periods as the glutaraldehyde concentration and cross-linking time increased . Implantation study of collagen hydrogels incorporating 125I-labeled VEGF revealed that the remaining VEGF radioactivity decreased with time and the retention period was prolonged with the decreased hydrogel biodegradation . The slower the hydrogel degradation, the longer the period of VEGF retention . The collagen hydrogel incorporating VEGF induced significant angiogenesis around the implanted hydrogel, in marked contrast to VEGF in the solution form and VEGF-free empty hydrogel . The retention period of angiogenesis became longer with a decrease of the in vivo degradation rate of hydrogels . It is possible that the slower degraded hydrogel achieves a longer period of VEGF release, resulting in prolonged angiogenetic effect . We concluded that in our hydrogel system, biologically-active VEGF was released as a result of in vivo degradation of the hydrogel.

Environ Pollut, 2001, 111(3), 407 - 15
Spatial variability in the degradation rate of isoproturon in soil; Walker A et al.; Thirty samples of soil were taken at 50-m intersections on a grid pattern over an area of 250 x 200 m within a single field with nominally uniform soil characteristics . Incubations of isoproturon (3-(4-isopropylphenyl)-1,1-dimethylurea) under standard conditions (15 degrees C; -33 kPa soil water potential) indicated considerable variation in degradation rate of the herbicide, with the time to 50% loss (DT50) varying from 6.5 to 30 days . The kinetics of degradation also varied between the sub-samples of soil . In many of them, there was an exponential decline in isoproturon residues; in others, exponential loss was followed by more rapid rates of decline; in a few soil samples, rapid rates of loss began shortly after the start of the incubations . In more detailed studies with soils from a smaller number of sub-sites (20), measurements were again made of isoproturon degradation rate, and the soils were analysed for organic matter content, pH, and nutrient status (N, P, K) . Measurements were also made of isoproturon adsorption by the soils and of soil microbial biomass . Patterns of microbial metabolism were assessed using 95 substrates in Biolog GN plates . Soils showing rapid biodegradation were generally of higher pH and contained more available potassium than those showing slower degradation rates . They also had a larger microbial biomass and greater microbial metabolic diversity as determined by substrate utilisation on Biolog GN plates . The implications of the results for the efficacy and environmental behaviour of isoproturon are discussed.

Environ Pollut, 2001, 112(1), 73 - 87
Immunotoxicity risks associated with land-treatment of petrochemical wastes revealed using an in situ rodent model; Rafferty DP et al.; Land-treatment of petrochemical wastes is a widely used method to dispose of hazardous and non-hazardous waste by biodegradation . However, no comprehensive assessment of the impact of such disposal techniques on terrestrial ecosystems has been conducted . Despite the presence of suspected immunotoxicants in the soil, wild rodents frequently reside on these waste sites after closure or abandonment . We explored the seasonal sensitivity of the immune system of the hispid cotton rat (Sigmodon hispidus) to in situ exposures on sites land-treated with petrochemical wastes . Animals were monitored on five contaminated land-treatment sites and five ecologically matched-reference sites in Oklahoma, USA, over two seasons (summer and winter) . Most hematological parameters were not adversely affected by land-treatment; however, platelet counts were 26% greater in cotton rats from land-treatment sites compared to reference sites in winter . Significant treatment-related differences were observed in total serum protein concentrations, organ mass and organ cellularity, but these differences were not consistent across the five land-treatment units . Lymphoproliferative responses of cotton rat splenocytes stimulated in vitro were elevated for a T-cell mitogen and depressed for a B-cell mitogen in animals from land-treatment compared to reference sites . The ability of splenocytes to proliferate in response to interleukin-2 receptor-binding was not influenced by treatment . Total yields of peritoneal cells, yield of peritoneal macrophages, and yield of peritoneal lymphocytes were influenced to varying degrees by land-treatment . Functionally, in vitro metabolic activity of peritoneal macrophages was 114% greater in cotton rats from land-treatment sites compared to reference sites during summer . These results indicate that petrochemical wastes applied to soils on these five land-treatment sites had variable immunomodulatory effects in resident cotton rats . Immune alterations for some assays were indicative of enhancement on some land-treatment sites while suppressive on other land-treatment sites, which could have been a function of type and concentration of immunotoxicants present on each site and highlights the uniqueness of each land-treatment site.

Biomaterials, 2001 Feb, 22(3), 195 - 200
Biocompatibility and biodegradation of intravitreal hyaluronan implants in rabbits; Avitabile T et al.; To study the biocompatibility and the biodegradation rate in vivo of new intravitreal implants made with three different hyaluronic acid esters: Hyaff7, Hyaff11 and Hyaff11p75 (100% ethyl ester, 100 and 75% benzyl esters, respectively), the plugs were implanted through a sclerotomy at 3.5 mm from the limbus of rabbit eyes . In order to evaluate the in vivo biodegradation the shaft diameter of the plugs was measured by ultrasound biomicroscopy . Slit lamp microscopy, ophthalmoscopy and ERG were performed periodically . The effects of the implants on ocular tissues were also evaluated histologically . All the plugs showed a good biocompatibilitv . Plugs of both the total esters, Hyaff7 and Hyaff11, were found to undergo a slow dissolution process for 60 and 150 days, respectively . The partial benzyl ester, Hyaff11p75, was completely reabsorbed after 15 days . Analysis of variance showed a high correlation between biodegradation rate and the time of resorption (F = 90.5; p < 0.001) . The biodegradation rate of each implant is related to the chemical structure of the three types of Hyaff (F = 4.51; p = 0.005) . The present data suggest that intravitreal implants based on hyaluronic acid esters represent useful biocompatible and biodegradable devices for a potential drug delivery system in the treatment of posterior segment ocular diseases.

Biodegradation, 2000, 11(1), 29 - 35
Distribution in the environment of degradative capacities for gasoline attenuation; Solano-Serena F et al.; A methodology allowing the detailed assessment of the capacities of microflorae to degrade gasoline in aerobic conditions has been developed . It consisted in the determination of the degradation of a gasoline model mixture in liquid cultures in optimal conditions . The gasoline model mixture contained 23 representative hydrocarbons of gasoline (GM23) . The kinetics and extent of biodegradation were evaluated by continuous overall monitoring of CO2 production and final chromatographic analysis (usually after about 30 days) of the consumption of each hydrocarbon . The methodology was used with soil and water samples from polluted and non polluted sites . The experimentation aimed at assessing the distribution of the degradative capacities in the environment and the prospects for natural attenuation of gasoline . Nine microflorae were tested . The intrinsic biodegradability (existence of mechanisms of biodegradation) appeared total for GM23 as shown by the results obtained with several microflorae . The degradative capacities of microflorae from non polluted samples were high (total degradation rates at least 85%) . Incomplete degradation was observed essentially for trimethylalkanes (2,2,4-trimethylpentane and 2,3,4-trimethylpentane) and for cyclohexane . In several cases, samples from polluted sites exhibited more extensive degradative capacities, with total degradation of all hydrocarbons being observed for three out of the six samples.

Biodegradation, 2000, 11(1), 21 - 8
Influence of phenol on biodegradation of p-nitrophenol by freely suspended and immobilized Nocardioides sp . NSP41; Cho YG et al.; The effect of the presence of an alternate toxic compound (phenol) on the p-nitrophenol (PNP)-degrading activity of freely suspended and calcium alginate immobilized Nocardioides sp . NSP41 was investigated . In the single substrate experiments, when the concentration of phenol and PNP was increased to 1400 mg l(-1) and 400 mg l(-1), respectively, the initial cell concentrations in the freely suspended cell culture should be higher than 1.5 g dry cell weight l(-1) for complete degradation . In the simultaneous degradation experiment, when the initial concentration of phenol was increased from 100 to 400 mg l(-1), the specific PNP degradation rate at the concentration of 200 mg l(-1) was decreased from 0.028 to 0.021 h(-1) . A freely suspended cell culture with a high initial cell concentration resulted in a high volumetric degradation rate, suggesting the potential use of immobilized cells for simultaneous degradation . In the immobilized cell cultures, although simultaneous degradation of PNP and phenol was maintained, the specific PNP and phenol degradation rate decreased . However, a high volumetric PNP and phenol degradation rate could be achieved by immobilization because of the high cell concentration . Furthermore, when the immobilized cells were reused in the simultaneous degradation of PNP and phenol, they did not lose their PNP- and phenol-degrading activity for 12 times in semi-continuous cultures . Taken together, the use of immobilized Nocardioides sp . NSP41 for the simultaneous degradation of PNP and phenol at high concentrations is quite feasible because of the high volumetric PNP and phenol degradation rate and the reusability of immobilized cells.

Biodegradation, 2000, 11(1), 11 - 9
Formation of the metabolic intermediate 2,4,4-trimethyl-2-pentanol during incubation of a Sphingomonas sp . strain with the xeno-estrogenic octylphenol; Tanghe T et al.; Degradation of branched octylphenol was studied in a bacterial culture of a Sphingomonas sp . strain . Octylphenol is considered to be the most stable degradation intermediate formed from the corresponding nonionic octylphenol polyethoxylates surfactants during biological wastewater treatment . Since octylphenol can exert estrogenic effects in wildlife, a detailed study of its biodegradation is warranted . The aerobic microbiological transformation of octylphenol was examined with and without the addition of the easily assimilable sodium acetate . In both cases the formation of the metabolite 2,4,4-trimethyl-2-pentanol, representing the intact alkyl chain as a tertiary alcohol, was observed . Since the octylphenol degradation rate was not affected by the presence of acetate, this strain did not show any diauxic metabolic behaviour when incubated with octylphenol and sodium acetate as the sources of carbon and energy . As a result of the biotransformation of octylphenol, its estrogenic potency was removed because it is the phenolic moiety that interacts with the estrogen receptors . This feature opens perspectives for the use of this strain in the framework of an adequate treatment of wastewater with high levels of alkylphenol polyethoxylates.

Structure Fold Des, 2000 Dec 15, 8(12), 1267 - 78
A cluster exposed: structure of the Rieske ferredoxin from biphenyl dioxygenase and the redox properties of Rieske Fe-S proteins; Colbert CL et al.; BACKGROUND: Ring-hydroxylating dioxygenases are multicomponent systems that initiate biodegradation of aromatic compounds . Many dioxygenase systems include Rieske-type ferredoxins with amino acid sequences and redox properties remarkably different from the Rieske proteins of proton-translocating respiratory and photosynthetic complexes . In the latter, the {Fe2S2} clusters lie near the protein surface, operate at potentials above +300 mV at pH 7, and express pH- and ionic strength-dependent redox behavior . The reduction potentials of the dioxygenase ferredoxins are approximately 150 mV and are pH-independent . These distinctions were predicted to arise from differences in the exposure of the cluster and/or interactions of the histidine ligands . RESULTS: The crystal structure of BphF, the Rieske-type ferredoxin associated with biphenyl dioxygenase, was determined by multiwavelength anomalous diffraction and refined at 1.6 A resolution . The structure of BphF was compared with other Rieske proteins at several levels . BphF has the same two-domain fold as other Rieske proteins, but it lacks all insertions that give the others unique structural features . The BphF Fe-S cluster and its histidine ligands are exposed . However, the cluster has a significantly different environment in that five fewer polar groups interact strongly with the cluster sulfide or the cysteinyl ligands . CONCLUSIONS: BphF has structural features consistent with a minimal and perhaps archetypical Rieske protein . Variations in redox potentials among Rieske clusters appear to be largely the result of local electrostatic interactions with protein partial charges . Moreover, it appears that the redox-linked ionizations of the Rieske proteins from proton-translocating complexes are also promoted by these electrostatic interactions.

Environ Microbiol, 1999 Apr, 1(2), 119 - 24
Predicting biodegradation; Wackett LP et al.; Biodegradation is important for natural and industrial cycling of environmental chemicals . Industries and government regulators increasingly seek to know the fate of chemicals in the environment and thus prevent potential negative impacts on human or ecosystem health . However, millions of organic compounds are known, and most will remain unstudied with respect to biodegradation . This necessitates the development of organized biodegradation information coupled with predictive methods . Biodegradation prediction methods are being developed using the information contained in the University of Minnesota Biocatalysis/ Biodegradation database . Heuristic rules are derived from compiled biodegradation information . Additional rules are generated by deconstructing compounds into a set of the 40 most common organic functional groups . The rules consist of deriving biochemically plausible catabolic reactions for each of the functional groups . More complex compounds, containing multiple functional groups, are analysed using higher order rules requiring prioritizing enzymatic attack and reactions cleaving functional groups . While biodegradation prediction, like weather prediction, will never be perfect, it can be an important tool for guiding industry, regulators and experimentalists.

Curr Interv Cardiol Rep, 2001 Feb, 3(1), 10 - 17
Biodegradable Polymeric Stents; Tsuji T et al.; To overcome several problems of conventional metallic stents, there have been many attempts to manufacture stents made of biodegradable materials . Although some studies have noted various degrees of inflammatory responses after biodegradable stent implantation, stents made of poly-l-lactic acid (PLLA) showed high biocompatibility with minimal inflammatory response and neointimal formation in porcine coronary arteries . Therefore, PLLA materials are more likely to cover the specific need for human coronary arteries in terms of biodegradation period and scaffolding ability over 6 months . A clinical study of PLLA self-expanding stent implantation is underway in Japan . The initial and 6-month results are favorable and suggest the feasibility, safety, and efficacy of the PLLA biodegradable stent in humans . However, long-term follow-up with larger numbers of patients will be required to validate the long-term efficacy of PLLA stents.

J, Exp . Mar . Biol . Ecol. . 2001 Feb 20, 257(1), 73 - 86
Biodegradation of photosynthetically produced extracellular organic carbon from intertidal benthic algae; Goto N et al.; 14C-labeled extracellular products of a natural microphytobenthic community and two species of benthic diatoms (Nitzschia hybridaeformis and Amphora coffeaeformis) were fractionated into extracellular dissolved organic carbon (14C-EDOC), organic carbon extracted with EDTA (14C-EDTA-extractable OC) and extracellular polymeric substances (14C-EPS) . The biodegradation of this labeled extracellular organic carbon by bacteria in sediments was examined to determine the processes of enzymatic degradation of photosynthetically-produced extracellular organic carbon from microphytobenthos in an intertidal flat ecosystem . In addition, primary production as well as extracellular enzyme activities (beta- and alpha-glucosidase) were measured to evaluate the possible relationship between organic carbon production and microbiological degradation at the Isshiki intertidal flat in Mikawa Bay, Japan . With all three 14C-fractions extracted from a natural microphytobenthic assemblage and two species of benthic diatoms, more than 50% of the added substrates were mineralized within 24 h by the bacterial community in sediments . At that time, the percentage of high-molecular-weight compounds (>5 K MW) to total MW compounds of 14C-EDTA-extractable OC and 14C-EPS fractions decreased within 24 h from 50.9 to 6.6% and 74.5 to 11.1%, respectively . In situ, beta- and alpha-glucosidase activity in sediment was higher than in the seawater column (at a depth of 1 m), though the photosynthetic production of microphytobenthos was equal to that of phytoplankton . Based on our previous studies that microphytobenthos produced much more extracellular products than phytoplankton, it is assumed from these results that carbon flowing into the microbial loop through the mediation of enzymatic degradation of extracellular products in a benthic system exceeds that in the overlying water column.

Clin Chim Acta, 2001 Feb, 304(1-2), 9 - 18
Various forms of plasma cysteine and its metabolites in patients undergoing hemodialysis; Wlodek PJ et al.; The thiol tripeptide glutathione (GSH) is particularly important as an antioxidative protector in the cells . GSH is also a form of storage and transport of cysteine . Under physiological conditions, the kidney plays an essential role in GSH biodegradation to free cysteine via gamma-glutamyl cycle and subsequently in further metabolism of this sulfur amino acid . Our aim was to assess to what degree renal insufficiency affects the level of various cysteine forms and its metabolites (sulfates and sulfane sulfur compounds) in the plasma, and whole blood GSH levels . The concentrations of all the above mentioned sulfur compounds were measured in plasma of patients with end stage renal failure (ESRF) before and after dialysis and in a group of healthy controls . In plasma of patients with ESRF before dialysis tendency towards significant elevation of cystine, protein-bound cysteine and sulfates levels was evident . Simultaneously, a decrease of plasma level of sulfane sulfur compounds, products of anaerobic sulfur metabolism, and whole blood GSH concentration was found . As a consequence, the ratio between the reduced cysteine and the total cysteine concentration was markedly decreased . The dialysis session restore this ratio to the value observed in plasma of control individuals . These findings indicate disturbances in the thiol-disulfide equilibrium and show a higher oxidation status in plasma of patients with ESRF than in healthy controls.

J, Exp . Mar . Biol . Ecol. . 2001 Jan 31, 256(2), 199 - 213
Alteration and release of aliphatic compounds by the polychaete Nereis virens (Sars) experimentally fed with hydrocarbons; Gilbert F et al.; In the laboratory, marine worms were fed with a mixture of algae and several aliphatic hydrocarbons for 15 days . After ingestion by the worms, 34.9% of hydrocarbons are found in the faeces and only 3.1% accumulated in the gut . The comparison between the initial mixture and the faeces shows that the worm's digestive process lead to changes in the distribution of the n-alkane mixture . These changes are different from those only due to physical processes in the experimental conditions . In our experiment, no variation in the distribution of hydrocarbons in faeces with time and no microbial hydrocarbon biodegradation were evidenced . Our results suggest that marine worm feeding can substantially affect the fate of hydrocarbons in the sedimentary marine ecosystem by predominantly stimulating dissolution processes.

Appl Environ Microbiol, 2001 Feb, 67(2), 821 - 6
Purification, stability, and mineralization of 3-hydroxy-2- formylbenzothiophene, a metabolite of dibenzothiophene; Bressler DC et al.; 3-Hydroxy-2-formylbenzothiophene (HFBT) is a metabolite found in many bacterial cultures that degrade dibenzothiophene (DBT) via the Kodama pathway . The fate of HFBT in cultures and in the environment is unknown . In this study, HFBT was produced by a DBT-degrading bacterium and purified by sublimation . When stored in organic solvent or as a crystal, the HFBT slowly decomposed, yielding colored products . Two of these were identified as thioindigo and cis-thioindigo . The supernatant of the DBT-degrading culture contained thioindigo, which has not been reported previously as a product of DBT biodegradation . In mineral salts medium, HFBT was sufficiently stable to allow biodegradation studies with a mixed microbial culture over a 3- to 4-week period . High-performance liquid chromatography analyses showed that HFBT was removed from the medium . 2-Mercaptophenylglyoxalate, detected as benzothiophene-2,3-dione, was found in an HFBT-degrading mixed culture, and the former appears to be a metabolite of HFBT . This mixed culture also mineralized HFBT to CO2.

Bioresour Technol, 2001 Jan, 76(2), 113 - 7
Biodegradation of polycyclic aromatic hydrocarbons (PAHs) by native microflora and combinations of white-rot fungi in a coal-tar contaminated soil; Canet R et al.; Four white-rot fungi (Phanerochaete chrysosporium IMI 232175, Pleurotus ostreatus from the University of Alberta Microfungus Collection IMI 341687, Coriolus versicolor IMI 210866 and Wye isolate #7) and all possible combinations of two or more of these fungi, were incubated in microcosms containing wheat straw and non-sterile coal-tar contaminated soil to determine their potential to degrade polycyclic aromatic hydrocarbons (PAHs) . Biotic and abiotic controls were prepared similarly and PAH concentrations remaining in each microcosm were determined after 8, 16 and 32 weeks by GC-MS following extraction with dichloromethane . The greatest PAH losses were in the biotic control, compared to small or negligible differences in microcosms inoculated with one or more fungi . These results suggest that in the biotic control native microorganisms colonised the straw added as organic substrate and degraded PAH as an indirect consequence of their metabolism . By contrast, in other microcosms, colonisation of straw by the natural microflora was inhibited because the straw was previously inoculated with fungi . Soil cultures prepared at the end of the experiment showed that though introduced fungi were still alive, they were unable to thrive and degrade PAH in such a highly contaminated soil and remained in a metabolically inactive form.

Arthroscopy, 2001 Jan, 17(1), 73 - 6
The fate of the poly-L-lactic acid interference screw after anterior cruciate ligament reconstruction; Martinek V et al.; We report the persistence of a poly-L-lactic acid (PLLA) interference screw 2.5 years after anterior cruciate ligament (ACL) reconstruction with Achilles tendon allograft . The arthroscopy was performed because the patient sustained a reinjury of the ACL graft, making ACL revision surgery necessary . At the time of arthroscopy, both PLLA screws were macroscopically still intact but could not be removed in 1 piece . No inflammation could be observed either macroscopically or in the histologic analysis . The biopsy specimen from the femoral insertion of the graft showed parts of the PLLA material surrounded by scar tissue . This case shows that biodegradation of PLLA material in the knee joint causes no irritation and can take several years, even if the material is in contact with the synovial fluid.

J Cell Physiol, 2001 Jan, 186(1), 95 - 103
Neutrophil-mediated biodegradation of medical implant materials; Labow RS et al.; During the acute inflammatory response to implanted medical devices, human neutrophils (PMN) release oxidative and hydrolytic activities which may ultimately contribute to the degradation of the biomaterial . In this study, the biological activities secreted by live PMNs which may contribute to biodegradation were investigated using a 14C label in the monomer unit of a poly(ester-urea-urethane) (PEUU) substrate . By using specific inhibitors, it was possible to propose a mechanism for PMN-mediated biodegradation . PMN, labeled with 3H-arachidonic acid, released significantly more 3H when adherent to PEUU than when adherent to tissue culture grade polystyrene (P<0.05) . The phospholipase A2 (PLA2) inhibitors, aristolochic acid (ARIST) and quinacrine (QUIN), decreased the release of 3H and inhibited PEUU biodegradation (>50%, P<0.05) . ARIST had no effect on cell viability, whereas QUIN significantly decreased it . The serine protease inhibitor, phenylmethylsulfonylfluoride inhibited biodegradation, but did not decrease cell survival . There is evidence to suggest that activation via the PLA2 pathway caused the release of hydrolytic activities which were able to elicit 14C release from PEUU . The role of oxidative compounds which were released via activation by phorbol myristate acetate (PMA), was not apparent, since PMA inhibited biodegradation and cell survival (>40%, P<0.05) . This study has shown that it is possible to find out the differences in PMN activation through the PLA2 pathway when exposed to different material surfaces, making this a model system worthy of further investigation.

C R Acad Sci III, 2000 Nov, 323(11), 945 - 50
{Biodegradability of Erika fuel oil}; Oudot J; The biodegradation of the fuel oil resulting from the Erika wreck was studied by computerized gas chromatography in laboratory cultures over 80 days . The total extent of biodegradation was around 11% . The degraded compounds were the molecules of the light cracking fraction used to dilute the distillation residue, as well as n-alkanes and part of the branched alkanes . Part of the polycyclic aromatic hydrocarbons PAH and alkyl PAH was also degraded . The very low biodegradability of the Erika fuel is attributable to its chemical composition . The product is rich in components that are inherently resistant or refractory to microbial metabolism such as resins, asphaltenes and polycyclic saturated and aromatic hydrocarbons.

Ecotoxicol Environ Saf, 2000 Nov, 47(3), 221 - 30
Probability of biodegradation, a novel concept for improving chemical classification and risk assessment; Blok J; In this article biodegradability is considered as a combination of an inherent substance property, defined as the maximum specific growth rate, mumax and a condition of the environment defined as a specific fraction (fs) of the total viable biomass . By proper analysis of test results it is possible to quantify both parameters by one single standard test . Calculations with literature data indicate that for the majority of the degradable substances, mumax may vary between 0.5 and 10 per day . The specific fractions, however, may vary 5 or 6 orders of magnitude and can be as low as 10(-8) . This concept gives a valuable tool in environmental risk assessment . As the results will be less influenced by test conditions, data will be more reproducible and can be more predictive for a specific environment . The results allow predicting the time needed to achieve adaptation in a treatment plant and, in particular, the behavior under conditions with discontinuous discharge . By using threshold criteria for mumax, fs, and percentage mineralization, a new classification scheme with eight different classes for biodegradability is proposed . Compared to the currently used system with two classes, the prediction of biodegradation will be more sophisticated . The proposed system differentiates for six types of inherently degradable substances and identifies those substances with an abnormal growth curve, due to inhibition or toxicity, poor water solubility, or incomplete mineralization . For these classes the proposed equations are not directly applicable and more research will be required to predict their behavior.

FEMS Microbiol Ecol, 2001 Jan, 34(3), 187 - 196
Phenotypic biomonitoring using multivariate flow cytometric analysis of multi-stained microorganisms; Wikstrom P et al.; A new method for monitoring phenotypic profiles of pure cultures and complex microbial communities was evaluated . The approach was to stain microorganisms with a battery of fluorescent dyes prior to flow cytometry analysis (FCM) and to analyse the data using multivariate methods, including principal component analysis and partial least squares . The FCM method was quantitatively evaluated using different mixtures of pure cultures as well as microbial communities . The results showed that the method could quantitatively and reproducibly resolve both populations and communities of microorganisms with 5% abundance in a diverse microbial background . The feasibility of monitoring complex microbial communities over time during the biodegradation of naphthalene using the FCM method was demonstrated . The biodegradation of naphthalene occurred to differing extents in microcosms representing three different types of aromatic-contaminated groundwater and a sample of bio-basin water . The FCM method distinguished each of these four microbial communities . The phenotypic profiles were compared with genotypic profiles generated by random-amplified polymorphic DNA analysis . The genotypic profiles of the microbial communities described only the microbial composition, and not their functional change, whereas the phenotypic profiles seemed to contain information on both the composition and the functional change of the microorganisms . Furthermore, event analysis of the FCM data showed that microbial communities with initially differing compositions could converge towards a similar composition if they had a capacity for high levels of degradation, whereas microbial communities with similar initial compositions could diverge if they differed in biodegrading ability.

Biotechnol Bioeng, 2001 Feb 5, 72(3), 339 - 45
Optimized mixtures of recombinant Humicola insolens cellulases for the biodegradation of crystalline cellulose; Boisset C et al.; The digestion of bacterial cellulose ribbons by ternary mixtures of enzymes consisting of recombinant cellulases (two cellobiohydrolases, Cel6A and Cel7A, and the endoglucanase Cel45A) from Humicola insolens was investigated over a wide range of mixture composition . The extent of digestion was followed by soluble sugar release (saccharification) analysis together with transmission electron microscopy (TEM) observations . It was found that the addition of minute quantities of Cel45A induced a spectacular increase in saccharification of the substrate with either Cel7A or the mixture of Cel6A and Cel7A . Conversely, only a moderate saccharification resulted from the mixing of Cel45A and Cel6A . This difference is believed to originate from (1) the occasional endo character of Cel6A and (2) the competition of Cel6A and Cel45A for the substrate sites that are sensitive to endo activity . Interestingly, the mixture of enzymes giving rise to the highest saccharification rate did not always correspond to mixtures of enzymes generating the highest synergy . TEM images revealed that the bacterial cellulose ribbons became at the same time cut and narrowed down under the action of an optimized mixture of the three enzymes .

Appl Environ Microbiol, 2001 Jan, 67(1), 162 - 71
Role of the DmpR-mediated regulatory circuit in bacterial biodegradation properties in methylphenol-amended soils; Sarand I et al.; Pathway substrates and some structural analogues directly activate the regulatory protein DmpR to promote transcription of the dmp operon genes encoding the (methyl)phenol degradative pathway of Pseudomonas sp . strain CF600 . While a wide range of phenols can activate DmpR, the location and nature of substituents on the basic phenolic ring can limit the level of activation and thus utilization of some compounds as assessed by growth on plates . Here we address the role of the aromatic effector response of DmpR in determining degradative properties in two soil matrices that provide different nutritional conditions . Using the wild-type system and an isogenic counterpart containing a DmpR mutant with enhanced ability to respond to para-substituted phenols, we demonstrate (i) that the enhanced in vitro biodegradative capacity of the regulator mutant strain is manifested in the two different soil types and (ii) that exposure of the wild-type strain to 4-methylphenol-contaminated soil led to rapid selection of a subpopulation exhibiting enhanced capacities to degrade the compound . Genetic and functional analyses of 10 of these derivatives demonstrated that all harbored a single mutation in the sensory domain of DmpR that mediated the phenotype in each case . These findings establish a dominating role for the aromatic effector response of DmpR in determining degradation properties . Moreover, the results indicate that the ability to rapidly adapt regulator properties to different profiles of polluting compounds may underlie the evolutionary success of DmpR-like regulators in controlling aromatic catabolic pathways.

Appl Microbiol Biotechnol, 2000 Nov, 54(5), 692 - 7
Anaerobic biodegradability of alkylphenols and fuel oxygenates in the presence of alternative electron acceptors; Puig-Grajales L et al.; Alkylphenols and fuel oxygenates are important environmental pollutants produced by the petrochemical industry . A batch biodegradability test was conducted with selected ortho-substituted alkylphenols (2-cresol, 2,6-dimethylphenol and 2-ethylphenol), fuel oxygenates (methyl tert-butyl ether, ethyl tert-butyl ether and tert-amylmethyl ether) and tert-butyl alcohol (TBA) as model compounds . The ortho-substituted alkylphenols were not biodegraded after 100 days of incubation under methanogenic, sulfate-, or nitrate-reducing conditions . However, biodegradation of 2-cresol and 2-ethylphenol (150 mg l(-1)) was observed in the presence of Mn (IV) as electron acceptor . The biodegradation of these two compounds took place in less than 15 days and more than 90% removal was observed for both compounds . Mineralization was indicated since no UV-absorbing metabolites accumulated after 23 days of incubation . These alkylphenols were also slowly chemically oxidized by Mn (IV) . No biodegradation of fuel oxygenates or TBA (1 g l(-1)) was observed after 80 or more days of incubation under methanogenic, Fe (III)-, or Mn (IV)-reducing conditions, suggesting that these compounds are recalcitrant under anaerobic conditions . The fuel oxygenates caused no toxicity towards acetoclastic methanogens activity in anaerobic granular sludge.

Appl Microbiol Biotechnol, 2000 Nov, 54(5), 605 - 18
Microbial degradation of explosives: biotransformation versus mineralization; Hawari J et al.; The nitroaromatic explosive 2,4,6-trinitrotoluene (TNT) is a reactive molecule that biotransforms readily under both aerobic and anaerobic conditions to give aminodinitrotoluenes . The resulting amines biotransform to give several other products, including azo, azoxy, acetyl and phenolic derivatives, leaving the aromatic ring intact . Although some Meisenheimer complexes, initiated by hydride ion attack on the ring, can be formed during TNT biodegradation, little or no mineralization is encountered during bacterial treatment . Also, although the ligninolytic physiological phase and manganese peroxidase system of fungi can cause some TNT mineralization in liquid cultures, little to no mineralization is observed in soil . Therefore, despite more than two decades of intensive research to biodegrade TNT, no biomineralization-based technologies have been successful to date . The non-aromatic cyclic nitramine explosives hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) lack the electronic stability enjoyed by TNT or its transformed products . Predictably, a successful enzymatic change on one of the N-NO2 or C-H bonds of the cyclic nitramine would lead to a ring cleavage because the inner C-N bonds in RDX become very weak (<2 kcal/mol) . Recently this hypothesis was tested and proved feasible, when RDX produced high amounts of carbon dioxide and nitrous oxide following its treatment with either municipal anaerobic sludge or the fungus Phanaerocheate chrysosporium . Research aimed at the discovery of new microorganisms and enzymes capable of mineralizing energetic chemicals and/or enhancing irreversible binding (immobilization) of their products to soil is presently receiving considerable attention from the scientific community.

Prikl Biokhim Mikrobiol, 2000 Nov-Dec, 36(6), 666 - 71
{Creation and use of a liquid substance based on association of petroleum-oxidizing bacteria}; Chugunov VA et al.; An association of four bacterial strains with high oil-oxidizing and bioemulsifying activities, psychrophilicity, resistance to chemical pollutants, and lack of pathogenicity was selected from a collection of natural oil-oxidizing microorganisms . A new liquid preparation containing stabilizers and preservatives that maintain the cell viability and oil-oxidizing activity during long-term storage was developed . A field experiment in oil-polluted sod-podzol and clay sand soils demonstrated that this preparation accelerated the biodegradation of oil and its individual fractions, especially in the presence of mineral and organic fertilizers . Treatment of oil-polluted soil with this preparation and additives decreased the oil-induced suppression of certain groups of soil microflora.

Prikl Biokhim Mikrobiol, 2000 Nov-Dec, 36(6), 631 - 6
{Microbiological degradation of asymmetrical dimethylhydrazine--a toxic component of rocket fuel}; Chugunov VA et al.; A possibility of microbiological cleaning of water and soil polluted with asymmetric dimethylhydrazine (ADMH), a highly toxic rocket fuel ingredient (RFI), was studied . Several isolates (bacteria, yeast, and micromycetes) capable of utilizing ADMH as the only source of nitrogen, carbon, and energy were isolated from RFI-polluted tundra soil . Acceleration of RFI biodegradation was achieved using a biosorbent that involved cells of the degrader strain immobilized on granulated activated carbon . Biological testing in Escherichia coli and cereals (wheat and barley) demonstrated that biodegradation significantly decreased the integral toxicity of solutions containing ADMH, suggesting its utility for microbiological cleaning of polluted territories.

Biotechnol Bioeng, 2001 Jan 20, 72(2), 177 - 84
Soya lecithin effects on the aerobic biodegradation of polychlorinated biphenyls in an artificially contaminated soil; Fava F et al.; The effects of the phytogenic surfactant soya lecithin (SL) on the aerobic biodegradation of polychlorinated biphenyls (PCBs) spiked into a synthetic soil were studied . Soil was spiked with both biphenyl (4 g/kg) and Fenclor 42 (1,000 mg/kg) and treated in aerobic batch slurry-phase microcosms (17.5% w/v) . Microcosms were prepared either with or without the exogenous aerobic PCB-dechlorinating bacterial co-culture ECO3 (inoculum:10(8) CFU/mL) . In some inoculated microcosms, SL was added at 15 or 30 g/kg . Indigenous bacteria having the capability of metabolizing biphenyl and 2-chlorobenzoic acid were found to develop in the microcosms during the experiment, and were responsible for the significant PCB biodegradation and dechlorination observed in the uninoculated controls . The addition of ECO3 bacteria resulted in only a slight PCB biodegradation increase . In the presence of SL, a higher availability of biphenyl- and chlorobenzoic acid-degrading bacteria and higher PCB biodegradation and dechlorination yields were observed; the effects increased proportionally with the concentration of the applied SL . A significant decrease of soil ecotoxicity was also revealed in SL-supplemented microcosms . At both concentrations, SL was found to be a good carbon source for both the indigenous and ECO3 bacteria, as well as a product capable of enhancing the PCB bioavailability in the microcosms.

Chemosphere, 2001 Jan, 42(3), 319 - 31
Determination of the aerobic biodegradability of polymeric material in aquatic batch tests; Pagga U et al.; Results of an international ring-test of two laboratory methods are presented for investigating the biodegradability of organic polymeric test materials in aquatic test systems based on respirometry and the evolution of carbon dioxide . These methods are developed further from the well-known standardized biodegradation tests ISO 9408 (1999) and ISO 9439 (1999), which have been successfully used for many years . The most important improvements are the extension of the test period up to six months, the increase of the buffer capacity and nutrient supply of the inorganic medium, an optimization of the inoculation, and optionally, the possibility of a carbon balance . A ring test, organized by the International Biodeterioration Research Group (IBRG), was run using a poly(,-caprolactone)-starch blend and an aliphatic-aromatic co-polyester as test materials and a microcrystalline cellulose powder as a reference material . The test results and the experience gained by the participants showed that the methods are suitable and practicable . The test methods have been meanwhile established as standards ISO 14851 (1999) and ISO 14852 (1999).

Chemosphere, 2001 Jan, 42(3), 309 - 18
The fate and persistence of trifluoroacetic and chloroacetic acids in pond waters; Ellis DA et al.; The environmental fate of trichloro-, dichloro-, and monochloroacetic acids, and trifluoroacetic acid was investigated using field aquatic microcosms and laboratory sediment-water systems . Trifluoroacetic acid was extremely persistent and showed no degradation during a one-year field study, though it appeared to undergo transient partitioning within an unknown pond phase as the temperature of the surroundings was reduced . Of the three chloroacetic acids, trichloro had the longest residence time (induction and decay) (approximately 40 d), dichloro the shortest (approximately 4 d), and monochloro an intermediate residence time (approximately 14 d) . Laboratory studies suggest that the biodegradation of trichloro-, dichloro-, and monochloroacetic acids leads primarily to the formation of chloride and oxalic, glyoxalic, and glycolic acids, respectively.

Chemosphere, 2001 Jan, 42(3), 285 - 99
Application of a mechanistic desorption-biodegradation model to describe the behavior of polycyclic aromatic hydrocarbons in peat soil aggregates; Mulder H et al.; A procedure was developed to obtain three size fractions (2360 < d(p) < 1000, 1000 < d(p) < 710, and 710 < d(p) < 425 microm) of stable aggregates from Koopveen peat soil by application of an intense mixing regime prior to sieving of the soil material . The organic matter content, aggregation structure and the microstructure of these aggregates were determined and the particles were artificially contaminated with naphthalene and phenanthrene via a solvent phase . A nonlinear Freundlich sorption isotherm was determined for the naphthalene contaminated soil aggregates (n = 0.39; K(F) = 1.13 x 10(-2) m(1.17) kg(-0.39)) . The applicability of a mathematical model, that describes sorption equilibrium, intraparticle mass-transfer, and nonlinear bacterial degradation kinetics, was tested by fitting results of dynamic desorption and biodegradation experiments, generated in this study and earlier work on the peat soil aggregates . The experimental data were described adequately although strong variations in the values of the fit parameter, the intra-particle porosity (0.30 < epsilon < 0.88), were found . This indicates the necessity of further investigations.

Appl Environ Microbiol, 2000 Dec, 66(12), 5457 - 9
Rapid dye decolorization method for screening potential wood preservatives; Borokhov O et al.; We developed a new screening method for potential wood preservatives based on decolorization of the dye Remazol Brilliant Blue R by extracellular oxidative agents produced by wood decay fungi . Oxidative biodegradation of lignin yielded decolorized zones around and under fungal cultures on a dyed agar medium . Inhibitory effects were detected by direct observation and measurement of the decolorized zones.

Appl Environ Microbiol, 2000 Dec, 66(12), 5393 - 8
Anaerobic oxidation of n-dodecane by an addition reaction in a sulfate-reducing bacterial enrichment culture; Kropp KG et al.; We identified trace metabolites produced during the anaerobic biodegradation of H(26)- and D(26)-n-dodecane by an enrichment culture that mineralizes these compounds in a sulfate-dependent fashion . The metabolites are dodecylsuccinic acids that, in the case of the perdeuterated substrate, retain all of the deuterium atoms . The deuterium retention and the gas chromatography-mass spectrometry fragmentation patterns of the derivatized metabolites suggest that they are formed by C---H or C---D addition across the double bond of fumarate . As trimethylsilyl esters, two nearly coeluting metabolites of equal abundance with nearly identical mass spectra were detected from each of H(26)- and D(26)-dodecane, but as methyl esters, only a single metabolite peak was detected for each parent substrate . An authentic standard of protonated n-dodecylsuccinic acid that was synthesized and derivatized by the two methods had the same fragmentation patterns as the metabolites of H(26)-dodecane . However, the standard gave only a single peak for each ester type and gas chromatographic retention times different from those of the derivatized metabolites . This suggests that the succinyl moiety in the dodecylsuccinic acid metabolites is attached not at the terminal methyl group of the alkane but at a subterminal position . The detection of two equally abundant trimethylsilyl-esterified metabolites in culture extracts suggests that the analysis is resolving diastereomers which have the succinyl moiety located at the same subterminal carbon in two different absolute configurations . Alternatively, there may be more than one methylene group in the alkane that undergoes the proposed fumarate addition reaction, giving at least two structural isomers in equal amounts.

Appl Environ Microbiol, 2000 Dec, 66(12), 5110 - 5
Enrichment and molecular characterization of a bacterial culture that degrades methoxy-methyl urea herbicides and their aniline derivatives; El-Fantroussi S et al.; Soil treated with linuron for more than 10 years showed high biodegradation activity towards methoxy-methyl urea herbicides . Untreated control soil samples taken from the same location did not express any linuron degradation activity, even after 40 days of incubation . Hence, the occurrence in the field of a microbiota having the capacity to degrade a specific herbicide was related to the long-term treatment of the soil . The enrichment culture isolated from treated soil showed specific degradation activity towards methoxy-methyl urea herbicides, such as linuron and metobromuron, while dimethyl urea herbicides, such as diuron, chlorotoluron, and isoproturon, were not transformed . The putative metabolic intermediates of linuron and metobromuron, the aniline derivatives 3, 4-dichloroaniline and 4-bromoaniline, were also degraded . The temperature of incubation drastically affected degradation of the aniline derivatives . Whereas linuron was transformed at 28 and 37 degrees C, 3,4-dichloroaniline was transformed only at 28 degrees C . Monitoring the enrichment process by reverse transcription-PCR and denaturing gradient gel electrophoresis (DGGE) showed that a mixture of bacterial species under adequate physiological conditions was required to completely transform linuron . This research indicates that for biodegradation of linuron, several years of adaptation have led to selection of a bacterial consortium capable of completely transforming linuron . Moreover, several of the putative species appear to be difficult to culture since they were detectable by DGGE but were not culturable on agar plates.

J Biomed Mater Res, 2001 Feb, 54(2), 189 - 97
Model systems to assess the destructive potential of human neutrophils and monocyte-derived macrophages during the acute and chronic phases of inflammation; Labow RS et al.; Isolated cell systems of human neutrophils (PMNs) and monocyte-derived macrophages (MDMs) were used to compare the destructive potential of these cells during the acute and chronic phases of inflammation, respectively . The contrast in the damage to poly(urethane)s (PUs) was monitored by measuring radiolabel release elicited from a (14)C-polyester-urea-urethane (PEUU) during incubation with both cell types . Human PMN were seeded onto polymer-coated glass slips and both radiolabel release as well as serine protease activity {assayed with N-benzyloxycarbonyl lysine thiobenzyl ester (BLT)} were measured 18 h later . Human monocytes were cultured on polystyrene tissue culture plates for 14 days, trypsinized, and seeded onto the polymer-coated glass slips; then, radiolabel release and esterase activity {assayed with p-nitrophenylbutyrate (PNB)} were measured after 18 h . Coverslips with MDM were also incubated for an additional 2 weeks . At 18 h postincubation with the PEUU, MDM elicited 25 times more radiolabel release per 10(6) cells than PMN at 18 h and continued to increase more than sevenfold over the 18-h value during the subsequent 14-day period . The BLT activity in PMN did not increase significantly during the 18-h incubation period, whereas the PNB activity in MDM increased more than fourfold . The MDM, but not the PMN elicited radiolabel release, was inhibited by the protein synthesis inhibitor cycloheximide, as was the increase in PNB activity . The data provide evidence for a hydrolytic role for MDM and, to a lesser extent PMN, in the biodegradation of implanted materials . The full implication of the release of polymer-derived chemical agents from this hydrolytic cleavage of the implanted biomaterials, on the propagation of the inflammatory response, remains to be elucidated .

J Biomed Mater Res, 2001 Jan, 54(1), 1 - 11
Biodegradable dextran-polylactide hydrogel network and its controlled release of albumin; Zhang Y et al.; The objective of this paper was to study the release of bovine serum albumin (BSA) from a series of biodegradable hydrogels having a wide range of hydrophilicity to hydrophobicity, swelling, and biodegradation properties . BSA was incorporated into a series of biodegradable hydrogels made from a dextran derivative of allyl isocyanate (dex-AI, as the hydrophilic constituent) and poly(DL-lactic acid) diacrylate macromer (PDLLAM, as the hydrophobic constituent) . The release kinetics of BSA from these dex-AI/PDLLAM hydrogels was studied . Laser confocal scanning microscopy was used to investigate the morphological change of the hydrogels, as well as BSA distribution in the hydrogels, as a function of dex-AI to PDLLAM composition ratio and incubation time . We found that the incorporation of PDLLAM into dex-AI reduced the initial burst release of BSA due to its more homogeneous distribution in the hydrogels . As the PDLLAM component increased, the rate of formation of a loose three-dimensional (3D) network structure increased; consequently, the sustained rate and extent of BSA release increased . Both release index and diffusion coefficient (from release kinetics data) increased as the PDLLAM component increased in the hydrogels . The data suggest that the release of BSA was controlled by both diffusion of BSA through swelling of the hydrophilic phase during an early stage, and degradation of the hydrophobic phase during a late stage, and also that the magnitude of diffusion versus degradation controlled release is dependent on composition ratio and immersion time .

Biodegradation, 1999, 10(6), 429 - 35
Efficiency of defined strains and of soil consortia in the biodegradation of polycyclic aromatic hydrocarbon (PAH) mixtures; Bouchez M et al.; The microbiological characteristics of the bacterial degradation of mixtures of five polycyclic aromatic hydrocarbons (PAH), phenanthrene, fluorene, anthracene, fluoranthene and pyrene, were investigated . Three pure bacterial strains using one or several of these PAH as carbon sources were selected . The interactions between PAH during the degradation of PAH pairs by each of these strains were studied and their effects on the kinetics and the balance of degradation were characterised . Competition between PAH and degradation by cometabolism were frequently observed . Mixed cultures of two or three strains, although possessing the global capacity to mineralise the set of five PAH, achieved limited degradation of the mixture . In contrast, a consortium from a PAH-contaminated soil readily mineralised the five-PAH mixture . The results suggested that soil consortia possessed a wider variety of strains capable to compensate for the competitive inhibition between PAH as well as specialised strains that mineralised potentially inhibitory PAH metabolites produced by cometabolism.

Chemosphere, 2000 Dec, 41(12), 1827 - 34
Peroxidative degradation of selected PCB: a mechanistic study; Koller G et al.; The enzyme-induced decomposition and biodegradation of PCB were investigated . 2,5-Dichlorobiphenyl (PCB 9) and 2,2',5,5'-tetrachlorobiphenyl (PCB 52) were used as example compounds to study efficiency and mechanism of the degradation processes . It was found that the application of horseradish peroxidase (HRP) together with defined amounts of hydrogen peroxide removed 90%, of the initial concentration of PCB 9 and 55% of the initial concentration of PCB 52 from an aqueous solution after a reaction period of 220 min . Dechlorination was observed as the initial step . Although the metabolites identified were mainly chlorinated hydroxybiphenyls, benzoic acids and non-substituted 1,1'-biphenyl, some higher chlorinated biphenyl isomers also appeared . The biodegradation of PCB 9 using the white rot fungus Trametes multicolor took about four weeks and reduction was about 80%, of the initial concentration . The metabolites produced (dichlorobenzenes, chlorophenols and alkylated benzenes) were not quite the same as those observed upon incubation with HRP.

Chemosphere, 2000 Aug, 41(3), 427 - 35
Correlation between inorganic (heavy metals) and organic (PCBs and PAHs) micropollutant concentrations during sewage sludge composting processes; Lazzari L et al.; The nature and congener composition of PCBs and PAHs present in sewage sludge composting processes was investigated . These studies included analysis of the most significant process parameters (such as pH, temperature, weight percentage variation) and in addition heavy metals whose typical composting speciation and behaviour were also considered in order to better understand organic compound time profiles . The significant correlation found between Pb, Cd, Cu and PCBs and between PAHs and Hg implies that quite a strong adsorption of PCBs onto organic matter takes place and also provides evidence for the volatilisation of PAHs . Chemical characteristics of inorganic species and organic compounds are summarised to account for the observed correlation and time trend profiles . Moreover, single congener concentrations demonstrate that the number of Cl substituents for PCBs and condensed benzene rings for PAHs determine to what extent they can be broken down for biodegradation and removed through volatilisation respectively.

Chemosphere, 2000 Nov, 41(9), 1463 - 8
Biodegradation of polycyclic aromatic hydrocarbons by a mixed culture; Yuan SY et al.; We investigated the potential biodegradation of polycyclic aromatic hydrocarbons (PAHs) by an aerobic mixed culture utilizing phenanthrene as its carbon source . Following a 3-5 h post-treatment lag phase, complete degradation of 5 mg/l phenanthrene occurred within 28 h (optimal conditions determined as 30 degrees C and pH 7.0) . Phenanthrene degradation was enhanced by the individual addition of yeast extract, acetate, glucose or pyruvate . Results show that the higher the phenanthrene concentration, the slower the degradation rate . While the mixed culture was also capable of efficiently degrading pyrene and acenaphthene, it failed to degrade anthracene and fluorene . In samples containing a mixture of the five PAHs, treatment with the aerobic culture increased degradation rates for fluorene and anthracene and decreased degradation rates for acenaphthene, phenanthrene and pyrene . Finally, it was observed that when nonionic surfactants were present at levels above critical micelle concentrations (CMCs), phenanthrene degradation was completely inhibited by the addition of Brij 30 and Brij 35, and delayed by the addition of Triton X100 and Triton N101.

Chemosphere, 2000 Nov, 41(9), 1431 - 9
Determination and identification of metabolites of the fungicides Iprodione and Procymidone in compost; Vanni A et al.; The main metabolites formed from Iprodione and Procymidone during the composting process have been isolated and identified by HPLC-DAD-MSD . After addition of the fungicides to the composting pile, we monitored the reaction of the two analytes and the formation of their degradation products for eight months . We verified the nature of the metabolites by comparison with those hypothesised in the literature and by comparison with the behaviour of an abiotic process in aqueous acetonitrile pH 6 and at 35 degrees C . After taking into account the different kinetic behaviours of the fungicides on degradation in compost and hydro-organic solution, breakdown pathways are proposed for biodegradation.

Chemosphere, 2000 Nov, 41(9), 1361 - 9
Biodegradation of a nonylphenol ethoxylate by the autochthonous microflora in lake water with observations on the influence of light; Mann RM et al.; Alkylphenol polyethoxylates (APE) are routinely used as additives in pesticide formulations . Biodegradation of APEs results in the accumulation of persistent short chain mono-, di- and tri-ethoxylates (AP1EO, AP2EO AP3EO) that are more toxic than the parent compounds and potentially oestrogenic . Accumulation of persistent APE metabolites in shallow or ephemeral waters may pose a hazard to aquatic fauna . This study has followed the degradation and formation of individual oligomers in freshwater in static die-away tests with and without illumination . Over 33 days in darkness there was a progressive and complete loss of long chain oligomers (NP8-17EO), transient increases and subsequent loss of short to medium chain oligomers (NP4-7EO), and large persistent increases (approximately 1000%) in short chain oligomers (NP1-3EO) . In the presence of illumination, biodegradation was retarded and heterotrophic bacterial proliferation was inhibited . After 33 days there was complete loss of long chain oligomers (NP9-17EO), incomplete loss of medium chain oligomers (NP6-8EO) and increases in short chain oligomers (NP1-5EO).

Chemosphere, 2000 Nov, 41(9), 1321 - 6
Influence of oxygen supply on heptadecane mineralization by Pseudomonas nautica; Bonin P et al.; The influence of different states of oxygen supply on heptadecane mineralization has been investigated in resting cell suspensions of Pseudomonas nautica . The rate of heptadecane biodegraded was constant for oxygen concentrations between 21% and 10% (v/v) (about 100% and 50% of air saturation, 230 and 110 microM, respectively) . A decline in biodegradation rates occurred for oxygen concentrations below 10% (about 50% of air saturation, 110 microM) and biodegradation stopped with 0.21% oxygen (2.3 microM) . In the presence of 1% (11 microM) of oxygen, no CO2 was produced, showing that complete mineralisation of heptadecane was blocked.

Biomaterials, 2000 Dec, 21(23), 2335 - 46
Synthetic biodegradable polymers as orthopedic devices; Middleton JC et al.; Polymer scientists, working closely with those in the device and medical fields, have made tremendous advances over the past 30 years in the use of synthetic materials in the body . In this article we will focus on properties of biodegradable polymers which make them ideally suited for orthopedic applications where a permanent implant is not desired . The materials with the greatest history of use are the poly(lactides) and poly(glycolides), and these will be covered in specific detail . The chemistry of the polymers, including synthesis and degradation, the tailoring of properties by proper synthetic controls such as copolymer composition, special requirements for processing and handling, and mechanisms of biodegradation will be covered . An overview of biocompatibility and approved devices of particular interest in orthopedics are also covered.

Sheng Wu Gong Cheng Xue Bao, 2000 Jul, 16(4), 505 - 8
{Kinetics for terephthalic acid anaerobic degradation with easily biodegradable organic material co-existence}; Li XM et al.; The fact of preferential substrate utilization results in a sequence of substrate attack . As typically, the easily biodegradable substrates in TA-containing wastewater are degraded firstly through methane fermentation pathway, and just those intermediate metabolites have been proved to be inhibitors for TA biodegradation . Moreover, TA itself can inhibit the TA biodegradation, too . A kinetic model for the anaerobic digestion of wastewater containing both TA and easily biodegradable pollutants is constructed as q = qmax {formula: see text}, The model parameters are estimated with non-linear regression method, the values are as follows: qmax = 1972.0 mgTA/gVSS.d; Ks = 20.2844 gTA/L; Ki,i = 2.041 gCOD/L; Ki,s = 0.0108 gTA/L . The experimental data verification for the model equation is satisfactory . According to the model analysis, a new strategy, a two-step anaerobic system, dealing with this kind of wastewater is suggested.

J Biotechnol, 2000 Oct 13, 83(3), 189 - 98
Microbial degradation of phenanthrene by addition of a sophorolipid mixture; Schippers C et al.; The influence of sophorolipids on microbial degradation of poorly soluble phenanthrene in liquid and soil suspension culture was evaluated in the work presented . Experiments were carried out in two parts . In the first part, important basic physico-chemical characteristics of the biosurfactant and the pollutant used were determined . The critical micelle concentration (CMC) and the solubilization ratio of the biosurfactant were found to be in a good range compared with synthetic surfactants . Also, a reduction to 71% of the detectable amount of phenanthrene was measured within 4 d in soil suspension without any biotic influence . In the second part, culture experiments were done with Sphingomonas yanoikuyae, the bacterium used throughout the work presented here with the aim to assess the toxicity of the sophorolipids on these bacteria and the effect of the surfactant on biodegradation . In exponential growth tests, no toxicity up to 1 g l(-1) sophorolipids could be detected, whereas in an agar plate test, slight growth hindrance was measured at a lower concentration of 250 mg l(-1) . The above mentioned data were important for planning further experiments . In the following cultivations with liquid and soil suspension media, enhancements of the biodegradation with surfactant addition were measurable . Fluorescence measurements showed that this effect was not due to an increasing biomass, but to an augmentation of bioavailability of the phenanthrene through increasing the apparent dissolved pollutant . Surfactant addition had the consequence of decreasing the residual detectable pollutant concentration (after 36 h 0.5 compared with 2.3 mg l(-1) soil suspension) and increasing the maximal degradation rate (127 instead of 80 mg l(-1) soil suspension x 10 h) . Therefore, the two main problems of biological soil remediation techniques, longer process time and residual pollutants, may be solved by the use of surfactants.

Prikl Biokhim Mikrobiol, 2000 Sep-Oct, 36(5), 515 - 24
{Plant potential for detoxification (review)}; Zaalishvili GV et al.; Data on the uptake, excretion, and biodegradation of organic xenobiotics by plants are reviewed . Detoxification pathways operating in plants and their role in remediation of biosphere are described . Structure-, concentration, and time-dependent effects of xenobiotics on the ultrastructural organization of cells are analyzed.

Onderstepoort J Vet Res, 2000 Jun, 67(2), 97 - 103
Stability and partitioning of closantel and rafoxanide in ruminal fluid of sheep; Swan GE et al.; The stability and the partitioning of closantel and rafoxanide in ruminal fluid (RF) was examined in vitro . Stability was evaluated in two studies in a ruminal fluid-artificial saliva (RF-AS) mixture containing either drug . Drug concentrations were measured in samples collected sequentially from four batches of RF-AS fortified with either closantel or rafoxanide in one study and in four separately incubated aliquots of a RF-AS mixture of each drug in the second study at the start and at various intervals during a 24 h incubation period . The viability of the in vitro RF-AS incubation model was validated by the presence of digoxin degradation (T1/2 of 39,1 +/- 13 h) and by the absence of significant time related differences (P> 0,5) in volume of gas produced, pH and methylene blue reduction time of the RF-AS drug mixture . Partitioning of closantel and rafoxanide was determined by measuring the relative drug concentration of the fluid and particulate phases in RF fortified with either drug at different concentrations . Closantel and rafoxanide were shown to be stable in a RF-AS mixture and were not subjected to any significant biodegradation . An initial marked reduction in drug concentration measured in the RF-AS mixture during the first 2 h of incubation was attributed to the attachment of both drugs onto particulate matter . This was subsequently confirmed in the partitioning study . More than 80% of closantel and rafoxanide was shown to be associated with the particulate phase of RF

Curr Opin Biotechnol, 2000 Oct, 11(5), 467 - 75
Bacterial promoters triggering biodegradation of aromatic pollutants; Diaz E et al.; Unraveling the complex transcriptional regulation of bacterial catabolism of aromatic pollutants is a prerequisite for engineering efficient biological systems for many biotechnological applications . A first level of regulation relies on specific regulator-promoter pairs . There have been new insights into the molecular mechanisms that regulatory proteins use to sense a given signal and to activate transcription initiation from the cognate promoters . A second level of regulation allows adjustment of the expression of the particular catabolic operons in response to the global environmental conditions of the cells, and recent findings provide some clues about the mechanisms underlying such complex regulatory checkpoints.

Ecotoxicol Environ Saf, 2000 Oct, 47(2), 105 - 11
Pseudomonas pickettii: a common soil and groundwater aerobic bacteria with pathogenic and biodegradation properties; Bruins MR et al.; Pseudomonas pickettii is an aerobic, nonfermentative, Gram-negative rod-shaped, bacterium that has been isolated from soil, water, humans, and recently the bovine intestinal tract . It belongs to the rRNA group II of the genus Pseudomonas and has three biovars: Va-1, Va-2, and biovar 3/thomasii . P . pickettii can cause pneumonia, meningitis, endocarditis, and osteomyelitis in humans . It frequently is associated with nosocomial infections that often are linked to contaminated injectable solutions . P . pickettii exhibits remarkable ability to degrade a variety of toxic compounds such as chlorophenols, aromatic hydrocarbons, 2,4-dichlorophenoxyacetic acid, and pentacyclic triterpeniod compounds . The genes that encode for these properties are chromosome- and plasmid-associated . Strains of the organism also have demonstrated resistance to heavy metals, such as cadmium, copper, and zinc . This species can survive in a nutrient-poor environment and use a variety of toxic compounds as carbon and energy sources, making it an ideal candidate for study in the biodegradation of toxic compounds found in wastewater and soils .

Bioorg Med Chem, 2000 Aug, 8(8), 2067 - 70
Biotransformations with Rhizopus arrhizus and Geotrichum candidum for the preparation of (S)-atenolol and (S)-propranolol; Damle SV et al.; (+/-)-Atenolol/(+/-)-propranolol and their acetates were incubated with the fungus Rhizopus arrhizus and Geotrichum candidum separately for different time intervals to afford (S)-atenolol/(S)-propranolol in good optical yield . The time and pH for this biotransformation was optimised . The present biodegradations using Rhizopus arrhizus and Geotrichum candidum provides a simple and useful method to obtain (S)-atenolol and (S)-propranolol which are active enantiomers of the beta-adrenergic blockers.

J Bacteriol, 2000 Oct, 182(19), 5448 - 53
Identification of a serine hydrolase which cleaves the alicyclic ring of tetralin; Hernaez MJ et al.; A gene designated thnD, which is required for biodegradation of the organic solvent tetralin by Sphingomonas macrogoltabidus strain TFA, has been identified . Sequence comparison analysis indicated that thnD codes for a carbon-carbon bond serine hydrolase showing highest similarity to hydrolases involved in biodegradation of biphenyl . An insertion mutant defective in ThnD accumulates the ring fission product which results from the extradiol cleavage of the aromatic ring of dihydroxytetralin . The gene product has been purified and characterized . ThnD is an octameric thermostable enzyme with an optimum reaction temperature at 65 degrees C . ThnD efficiently hydrolyzes the ring fission intermediate of the tetralin pathway and also 2-hydroxy-6-oxo-6-phenylhexa-2,4-dienoic acid, the ring fission product of the biphenyl meta-cleavage pathway . However, it is not active towards the equivalent intermediates of meta-cleavage pathways of monoaromatic compounds which have small substituents in C-6 . When ThnD hydrolyzes the intermediate in the tetralin pathway, it cleaves a C-C bond comprised within the alicyclic ring of tetralin instead of cleaving a linear C-C bond, as all other known hydrolases of meta-cleavage pathways do . The significance of this activity of ThnD for the requirement of other activities to mineralize tetralin is discussed.

Arch Microbiol, 2000 Jul-Aug, 174(1-2), 111 - 9
Sulfolane degradation by mixed cultures and a bacterial isolate identified as a Variovorax sp; Greene EA et al.; Sulfolane (tetrahydrothiophene-1,1-dioxide) is used in the Sulfinol process for natural gas sweetening . At many sour-gas processing plants spills, landfills and leakage from unlined surface storage ponds have contaminated groundwaters with sulfolane . Due to its high water solubility and mobility in aquifers, sulfolane poses a risk for off-site contamination . This study investigated the aerobic biodegradation of sulfolane by two mixed microbial enrichment cultures and by three bacterial isolates . Sulfolane served as the sole C, S and energy source for these cultures . In the two mixed cultures, 60% and 80% of the sulfolane C was recovered as CO2, whereas in cultures of the three isolates only 40-42% of the substrate C was recovered as CO, . In the mixed cultures, 81% and 97% of the sulfolane S was converted to sulfate, and in the pure isolates, 55-90% of the substrate S was converted to sulfate . Thus, the mixed cultures were capable of greater mineralization than the pure isolates . One isolate, strain WP1, was identified using a combination of 16S rRNA gene sequencing, physiological traits and cell morphology . WP1 was determined to be most similar to Varioivorax paradoxus.

J Chromatogr A, 2000 Aug 11, 889(1-2), 211 - 9
Handling of marine and estuarine samples for the determination of linear alkylbenzene sulfonates and sulfophenylcarboxylic acids; Leon VM et al.; Due to the physicochemical properties of linear alkylbenzene sulfonates (LAS), an anionic surfactant, it is difficult to obtain representative samples from sampling sites . Further, the high biodegradability of these compounds makes it necessary to study their biodegradation intermediates, sulfophenylcarboxylic acids (SPC) that do not have a surfactant character and show a different behavior . A procedure for determining and quantifying LAS and SPC in different environmental matrices by Soxhlet and solid-phase extractions and high-performance liquid chromatography is presented . The recoveries varied in the range from 85 to 102% for the water samples, and from 75 to 105% for sediment samples, with a standard deviation of between 1 and 7, and 2 and 11, respectively . Detection limits obtained were in the range from 5 to 10 microg kg(-1) for sediment samples (10 g) and from 0.2 to 0.4 microg l(-1) for water samples (250 ml) . The method was applied to the simultaneous determination of LAS (C10-C13) and SPC (C4-C13) homologues in water, sediment and interstitial water collected from different areas of Spain.

J Chromatogr A, 2000 Aug 11, 889(1-2), 177 - 84
Analytical techniques used for monitoring the biodegradation of fluorinated compounds in waste streams from pharmaceutical production; New AP et al.; During the assessment of the environmental impact of new pharmaceutical processes the selection and testing of suitable environmental treatment technologies is carried out . A large component of process waste stream treatment practice is aerobic biotreatment in wastewater treatment plants, as it is cost effective and generally more environmentally friendly than harsher chemical/physical treatments . Pharmaceutical syntheses use a range of halogenated compounds (either as reagents, solvents or intermediates) which pose particular challenges to microbial degradation . This is especially so for some fluorinated compounds due to the resilience to enzymatic cleavage of the C-F bond in some cases . The data presented here were obtained from a case study involving the monitoring of the biodegradation of 4-fluorocinnamic acid by means of a range of chromatographic techniques . These methods were used to monitor not only the disappearance of the compound but also the formation of degradation products in order to confirm mineralisation . In addition mass spectrometry was used to elucidate the metabolic pathway.

J Biomed Mater Res, 2000 Sep, 53(5), 592 - 9
Study of biodegradation behavior of chitosan-xanthan microspheres in simulated physiological media; Chellat F et al.; Microspheres of a polyelectrolyte complex hydrogel were prepared from chitosan and xanthan after interaction between the two polyionic polymers . Their biodegradation was studied vs . chitosan . Simulated gastric fluid (SGF, pH 1.2) and intestinal fluid (SIF, pH 7.5) both as biodegradation media and phosphate buffered saline (PBS, pH 7.4) as a negative control were used . The degradation studies were performed at 37 degrees C at 240 rpm permanent stirring to mimic the physiologic conditions . High performance liquid chromatography (HPLC) was carried out to quantify the chitosan degradation products using glucosamine (GA) and N-acetyl-D-glucosamine (N-Ac-GA) as references . The peaks area integration method was used to determine the amount of each degradation product as a function of incubation time in the media . The effect of the media on the morphological structure of microspheres was assessed by scanning electron microscopy . From HPLC studies, it appeared that in SGF and SIF the major degradation products were glucosamine (GA) and N-acetyl-D-glucosamine (NAc-GA) . In the first 15 days, oligochitosan fractions were released from the complex, whereas N-acetyl-D-glucosamine was detected in the media after this period . The degradation kinetics were assessed by the measurement of the cumulative degradation products, which showed faster degradation of chitosan than the complex in SGF and SIF . SEM micrographs showed an enhancement of microsphere porosity as a function of incubation time in the simulated physiological media . Our results suggest a better control of the degradation kinetics when chitosan is complexed to xanthan .

Acta Cient Venez, 2000, 51(1), 39 - 44
{Biodegradation of Venezuelan woods in field stake tests in the western lowlands}; Encinas O; Following known standards, a Field Test Site was established in Bum Bum area, located in Ticoporo Forest Reserve, tropical dry forest, Barinas State, Venezuela, for the study of wood biodegradation . Wood stakes from various wood species particularly Caribbean pine, with 500 mm x 50 mm x 25 mm in dimensions, were treated with several chemicals and concentrations and were installed in natural soil together non treated wood samples . Results concerning natural and induced durability are discussed; observations in Caribbean pine wood showed that the termite attack was responsible for failure of all non treated stakes and some samples treated with triazoles . Together Soft rot Type I and Tunnelling bacterial attack, termites are the main wood biodegradation agents.

Eur J Biochem, 2000 Sep, 267(18), 5815 - 20
Catalytic reductive dehalogenation of hexachloroethane by molecular variants of cytochrome P450cam (CYP101); Walsh ME et al.; CYP101 (cytochrome P450cam) catalyses the oxidation of camphor but has also been shown to catalyse the reductive dehalogenation of hexachloroethane and pentachloroethane . This reaction has potential applications in the biodegradation of these environmental contaminants . The hexachloroethane dehalogenation activity of CYP101 has been investigated by mutagenesis . The effects of active-site polarity and volume were probed by combinations of active-site mutations . Increasing the active-site hydrophobicity by the Y96A and Y96F mutations strengthened hexachloroethane binding but decreased the rate of reaction . Increasing the polarity with the F87Y mutation drastically weakened hexachloroethane binding but did not affect the rate of reaction . The Y96H mutation had little effect at pH 7.4, but weakened hexachloroethane binding while increasing the rate of dehalogenation by up to 40% at pH 6.5, suggesting that the imidazole side-chain was partially protonated at pH 6.5 but not at pH 7.4 . Substitutions by bulkier side-chains at F87, T101 and V247 weakened hexachloroethane binding but increased the dehalogenation rate . The effect of the individual mutations was additive in multiple mutants, and the most active mutant for hexachloroethane reductive dehalogenation at pH 7.4 was F87W-V247L (80 min-1 or 2.5 x the activity of the wild-type) . The results suggested that the CYP101 active site shows good match with hexachloroethane, the Y96 side-chain plays an important role in both hexachloroethane binding and dehalogenation, and hexachloroethane binding and dehalogenation places conflicting demands on active-site polarity and compromises were necessary to achieve reasonable values for both.

Appl Microbiol Biotechnol, 2000 Aug, 54(2), 268 - 73
Biodegradation of azo dyes in a sequential anaerobic-aerobic system; Rajaguru P et al.; A sequential anaerobic aerobic treatment process based on mixed culture of bacteria isolated from textile dye effluent-contaminated soil was used to degrade sulfonated azo dyes Orange G (OG), Amido black 10B (AB), Direct red 4BS (DR) and Congo red (CR) . Under anaerobic conditions in a fixed-bed column using glucose as co-substrate, the azo dyes were reduced and amines were released by the bacterial biomass . The amines were completely mineralized in a subsequent aerobic treatment using the same isolates . The maximum degradation rate observed in the treatment system for OG was 60.9 mg/l per day (16.99 mg/g glucose utilized), for AB 571.3 mg/l per day (14.46 mg/g glucose utilized), for DR 112.5 mg/l per day (32.02 mg/g glucose utilized) and for CR 134.9 mg/l per day (38.9 mg/g glucose utilized).

Int Arch Occup Environ Health, 2000 Jun, 73 Suppl, S75 - 8
Biodegradability of inhaled p-aramid respirable fibre-shaped particulates: representative of other synthetic organic fibre-types?
Warheit DB, Hartsky MA, Webb TR.
OBJECTIVES: Biopersistence, or alternatively, biodegradability (i.e., low biopersistence) represents an important concept in fibre toxicology . The studies described below were undertaken to investigate the mechanisms through which inhaled para-aramid (p-aramid) respirable, fibre-shaped particulates (RFP) are biodegraded in the lungs of exposed rats and hamsters; in contrast, cellulose fibres, another organic fibre-type, are known to be biopersistent . To investigate the mechanisms of RFP biodegradation, we have hypothesized that lung fluids activate p-aramid RFP following deposition, and the RFP are then vulnerable to enzymatic attack in the lungs . METHODS: To test the hypothesis, p-aramid RFP or cellulose RFP were instilled into the lungs of rats and the lungs digested 24 h post-exposure using two different digestion techniques: (1) a conventional ethanolic KOH method, and (2) an enzymatic method which simulates lung enzymes . RESULTS: The enzymatic but not the KOH method artificially cleaved the p-aramid RFP recovered from rat lungs . Next, p-aramid RFP or cellulose RFP were incubated with saline or lung fluids and then processed by one of the two digestion techniques . Mean lengths of p-aramid RFP processed with KOH and evaluated by SEM were 13.4 microm; in contrast, mean lengths of p-aramid RFP samples, incubated in lung fluids and treated with the enzymatic method were 8.8 microm . The enzymatic digestion method had no discernible effect on shortening of cellulose RFP, indicating that the results with p-aramid were specific . CONCLUSIONS: Our data indicate that components of lung fluids coat and catalyze the p-aramid, thereby predisposing the RFP to enzymatic cleavage . This could play a significant mechanistic role in facilitating the transverse cleavage or shortening of inhaled p-aramid RFP in the lungs of exposed rats and hamsters.

Appl Environ Microbiol, 2000 Aug, 66(8), 3187 - 93
Common degradative pathways of morpholine, thiomorpholine, and piperidine by Mycobacterium aurum MO1: evidence from (1)H-nuclear magnetic resonance and ionspray mass spectrometry performed directly on the incubation medium; Combourieu B et al.; In order to see if the biodegradative pathways for morpholine and thiomorpholine during degradation by Mycobacterium aurum MO1 could be generalized to other heterocyclic compounds, the degradation of piperidine by this strain was investigated by performing (1)H-nuclear magnetic resonance directly with the incubation medium . Ionspray mass spectrometry, performed without purification of the samples, was also used to confirm the structure of some metabolites during morpholine and thiomorpholine degradation . The results obtained with these two techniques suggested a general pathway for degradation of nitrogen heterocyclic compounds by M . aurum MO1 . The first step of the degradative pathway is cleavage of the C---N bond; this leads formation of an intermediary amino acid, which is followed by deamination and oxidation of this amino acid into a diacid . Except in the case of thiodiglycolate obtained from thiomorpholine degradation, the dicarboxylates are completely mineralized by the bacterial cells . A comparison with previously published data showed that this pathway could be a general pathway for degradation by other strains of members of the genus Mycobacterium.

Can J Microbiol, 2000 Jun, 46(6), 550 - 8
Thatch biodegradation and antifungal activities of two lignocellulolytic Streptomyces strains in laboratory cultures and in golf green turfgrass; Chamberlain K et al.; The use of lignocellulolytic Streptomyces spp . as biological agents, to enhance thatch degradation in turf and to slow its rate of accumulation while controlling fungal growth in the thatch layer, was studied . In flask scale studies, two lignocellulolytic Streptomyces violaceusniger (= hygroscopicus) strains (YCED9 and WYE53) decomposed thatch (> 30% dry weight) over a 12-week incubation period . Biodegradation was accompanied by production of extracellular cellulases, xylanases, and peroxidases . The accumulation of the polymeric, water-soluble lignin degradation intermediate acid, precipitable polymeric lignin (APPL), was also observed . Residual thatch from 12-week-old cultures had an increased lignin-to-carbohydrate ratio, an indication that although lignin was metabolized, carbohydrates were preferential carbon sources for these actinomycetes . A spore-containing soluble dry powder formulation was used as an inoculum in an in situ field experiment . This formulation was maintained in storage at 4 degrees C for over two years without viability loss . Results from the golf green experiment showed that although treated thatch layers in established greens were not appreciably reduced over the course of one summer, the Streptomyces were active and maintained their populations within the thatch, while fungal growth was suppressed as compared to controls . The results show that treatment of turfgrass with these Streptomyces may be useful for the long-term control of fungal populations within the thatch . Longer field studies are required to assess the long-term potential for also controlling thatch build-up and fungal pathogens.

FEMS Microbiol Lett, 2000 Aug 1, 189(1), 25 - 9
Properties of a bacterium which degrades solid poly(tetramethylene succinate)-co-adipate, a biodegradable plastic; Uchida H et al.; Various microorganisms were screened for their ability to degrade poly(tetramethylene succinate)-co-(tetramethylene adipate) (PBSA) . Strain BS-3, which was newly isolated from a soil sample, was selected as the best strain . From taxonomical studies, the strain was tentatively ascribed to belong to the genus Acidovorax, most probably to the species A . delafieldii . Strain BS-3 could degrade both solid and emulsified PBSA, and also emulsified poly(tetramethylene succinate) . During the degradation, a lipase activity was observed in the culture broth . This lipase activity was induced more strongly by PBSA than by tributyrin or triolein which are typical substrates of lipase . These observations strongly suggest that this lipase was involved in the PBSA biodegradation in strain BS-3.

Curr Med Chem, 2000 Sep, 7(9), 945 - 70
Conformational and topographical considerations in designing agonist peptidomimetics from peptide leads; Hruby VJ et al.; The design of peptidomimetic ligands with agonist biological activities in vitro and in vivo has been challenging . Lofty goals have been set for this research including high potency, high receptor type selectivity, high stability in vitro and in vivo, and high efficacy in vitro and in vivo for agonists . A systematic stepwise strategy has been developed to accomplish these goals . These include determining the primary amino acid side chain residues required for molecular recognition and, in the case of agonist activity, those required for information transduction . In addition to determining the preferred backbone conformation which can serve as a template for the bioactive conformation (an alpha-helix, beta-turn, beta-sheet, etc.), a strategy has been developed to examine and determine the preferred side chain conformations in chi space (chi1, chi2, etc.) . These include specific covalent and non-covalent constraints which can place the constrained side chains at highly preferred gauche (-), or gauche (+), or trans conformations . Examples are provided that illustrate this methodology and provide insight into the topographical requirements for ligand receptor interactions . Often, at this juncture one can obtain a quite precise 3D pharmacophore for the ligand, as well as high stability to agonist biodegradation and good bioavailability including the ability to cross membrane barriers . If a non-peptide ligand is desired, efforts are in progress to develop templates, and aspects of conformational design that permit assembling of all components necessary for molecular recognition and transduction . Here the proper choice of template that can place the key side chain residue in 3D space is still difficult, and thus only partial success has been achieved in terms of potent and selective ligands . A few of these approaches are presented and discussed in some detail.

DNA Seq, 2000, 11(1-2), 51 - 60
Isolation and analysis of three peroxide sensor regulatory gene homologs ahpC, ahpX and oxyR in Streptomyces viridosporus T7A--a lignocellulose degrading actinomycete; Ramachandran S et al.; Increased lignolytic peroxidase activity has been demonstrated with the addition of sublethal doses of toxic H2O2 in Streptomyces viridosporus T7A . Until now, the effect of H2O2 at the molecular level has not been well characterized . Here, for the first time we report the isolation and analysis of three peroxide-induced gene homologs from S . viridosporus T7A; ahpC and ahpX (encoding alkyl hydroxyperoxidase subunits) and oxyR (encoding oxygen stress regulatory protein) . The genome organization of these stress related genes were found to be divergently adjacent to each other . The protein sequence analysis of the oxyR homolog revealed a helix-turn-helix DNA-binding motif characteristic to the LysR of regulatory proteins induced by H2O2 . The nucleotide sequence analysis of the intergenic region between ahpC and oxyR revealed that they shared a core T-n11-A, a signature protein-binding region of LysR family members . Based on similarities in sequence analysis, genetic organization, and the induction of lignin peroxidase activity upon exposure to hydrogen peroxide, we hypothesize a peroxide induction mechanism for the regulation of oxidative lignin biodegradation by S . viridosporus, possibly via use of OxyR which is also involved in regulating the peroxide stress response in this actinomycete.

DNA Seq, 2000, 11(1-2), 9 - 20
Cloning of genes participating in aerobic biodegradation of p-cumate from Rhodopseudomonas palustris; Puskas LG et al.; Rhodopseudomonas palustris utilizes p-cumate as a carbon source both under anaerobic light and aerobic dark conditions . A gene cluster was isolated whose sequence showed high homology to genes which have been implicated the degradation of p-cumate in Pseudomonas pitida . Seven structural genes coding for dioxygenase-reductase, dihydroxy-dihydro dehydrogenase, and ring cleavage oxygenases were identified . A putative regulator and its possible recognition site was suggested on the basis of homology data . Mutant cells in which a kanamycin cassette was inserted into the dihydroxy-dihydro dehydrogenase gene could not grow aerobically on p-cumate . The mutation had no effect on growth using the para substituted benzoate derivatives 4-hydroxycinnamate, ferulate, protocatechuate, and 2,3,4-trihydroxybenzoate as sole carbon source . Moreover, mutant cells showed a growth pattern similar to wild type cells grown on these compounds under photoheterotrophic anaerobic conditions . These data suggest that genes of this operon are involved specifically in aerobic dissimilation of p-cumate . Intermediate products of p-cumate degradation could be detected from extracts of Escherichia coli heterologously expressing the first 5 genes responsible for the first two steps of p-cumate degradation in R . palustris . Primer extension analysis revealed the transcription regulation of the gene cluster which could be induced with para methyl-, ethyl- and isopropyl (cumate) benzoates . This is the first report on genes involved in aerobic degradation of these compounds in photosynthetic bacteria.

Chemosphere, 2000 Oct, 41(8), 1245 - 8
Microbial degradation of phthalic acid esters under anaerobic digestion of sludge; Jianlong W et al.; The microbial degradation by anaerobic sludge of three phthalates, priority pollutants, listed by both China National Environmental Monitoring Center and the U.S.EPA, namely, dimethyl (DMP), di-n-butyl (DBP) and di-n-octyl (DOP) phthalates was investigated . The experimental results indicated that the biodegradation rate and the biodegradability of three phthalates under anaerobic conditions appeared to be related to the length of the alkyl-side chains . More than 90% of DMP and DBP with the short alkyl-side chain phthalates can be degraded, whereas the DOP degradation appeared to be relatively slow under the same experimental conditions . The quantity of methane produced was measured and the results showed that both the ester groups and the phthalate ring were mineralized at a significant rate . The kinetics study demonstrated that the biodegradation of three phthalates conformed to the first-order model with respect to their concentrations.

FEBS Lett, 2000 Jul 14, 477(1-2), 79 - 83
Do the extracellular enzymes cellobiose dehydrogenase and manganese peroxidase form a pathway in lignin biodegradation?
Hilden L, Johansson G, Pettersson G, Li J, Ljungquist P, Henriksson G.
The extracellular enzyme manganese peroxidase is believed to degrade lignin by a hydrogen peroxide-dependent oxidation of Mn(II) to the reactive species Mn(III) that attacks the lignin . However, Mn(III) is not able to directly oxidise the non-phenolic lignin structures that predominate in native lignin . We show here that pretreatment of a non-phenolic lignin model compound with another extracellular fungal enzyme, cellobiose dehydrogenase, allows the manganese peroxidase system to oxidise this molecule . The mechanism behind this effect is demethoxylation and/or hydroxylation, i.e . conversion of a non-phenolic structure to a phenolic one, mediated by hydroxyl radicals generated by cellobiose dehydrogenase . This suggests that cellobiose dehydrogenase and manganese peroxidase may act in an extracellular pathway in fungal lignin biodegradation . Analytical techniques used in this paper are reverse-phase high-pressure liquid chromatography, gas chromatography connected to mass spectroscopy and UV-visible spectroscopy.

Front Med Biol Eng, 2000, 10(2), 79 - 82
Interaction between tissues and implantable materials; Lewandowska-Szumiel M et al.; Interaction between tissues and implantable materials is a factor of critical importance in biocompatibility studies . Bioactivity of implants is expected when the resorption or controlled integration of the implant with surrounding tissues is required . On the contrary, biomaterial inertness is suitable in the case of most load-bearing implants . Both desired and undesired consequences of partial implant biodegradation are discussed on the base of the authors' experimental work done on alumina and carbon-fiber-reinforced carbon composites (CFRC) . Two examples of investigations of the interaction between bioceramics (CFRC, alumina, hydroxyapatite, and tricalcium phosphate) and cells in culture are shown as an alternative to the methods based on experimental implantation . The future of research on biomaterial-tissue interaction is discussed with respect to the developments in tissue engineering.

J Microencapsul, 2000 Jul-Aug, 17(4), 509 - 18
Evaluation of 99mTc labelled poly lactic acid microspheres for diagnostic radioembolization; Ergun EL et al.; Radioembolization is used in diagnostic imaging of the lungs and for radioembolization therapy of hepatic tumours . Presently, 99mTc labelled macroaggregates or microspheres of human serum albumin (HAM) are used for this purpose . Poly lactic acid (PLA) is biodegradable, like HAM, and, unlike HAM, is not a blood product . The aim of the present study was to evaluate the uptake and biodegradation of PLA microspheres in lungs . PLA (MW = 48720 Da) microspheres of 1.0-100 microm (mean = 39.5 microm) in diameter were prepared by solvent evaporation from methylene chloride . They were labelled with 99mTc by stannous chloride reduction at pH 3, with an efficiency of 98% and a stability of 96% at 24 h . For biodistribution studies, 15 mice were i.v . injected with 20 microCi 99mTc-PLA microspheres in 0.1 ml and sacrificed at 15 min, 1, 3, 6 and 24 h (three at each time point) . All the organs were removed, weighed and counted against a standard prepared from 1/100 dilution of the injected radioactivity . Some mice were similarly injected and sacrificed at 30 min, 15 and 30 days . The lungs were removed and frozen, and 10 microm sections were obtained, stained with haemotoxylin and eosin and examined under a light microscope . Five rabbits were i.v . injected with 1 mCi of 99mTc-PLA microspheres . Scintigrams were obtained at various intervals up to 24 h . In mice, the lung uptake was significant at 30 min-1h post-injection . In rabbits, the lungs were the only organs visualized up to 24 h . Microscopic examination of tissue sections demonstrated slow biodegradation of PLA particles . In conclusion; (1) The high lung uptake obtained in mice and rabbits indicates the suitability of PLA microspheres for lung imaging, and (2) although the slow biodegradation rate might be a disadvantage in patients with lung disorders in diagnostic studies, it may be an advantage in therapeutic applications with radionuclides which have long physical half lives.

Appl Environ Microbiol, 2000 Jul, 66(7), 3010 - 5
Reactions involved in the lower pathway for degradation of 4-nitrotoluene by Mycobacterium strain HL 4-NT-1; He Z et al.; In spite of the variety of initial reactions, the aerobic biodegradation of aromatic compounds generally yields dihydroxy intermediates for ring cleavage . Recent investigation of the degradation of nitroaromatic compounds revealed that some nitroaromatic compounds are initially converted to 2-aminophenol rather than dihydroxy intermediates by a number of microorganisms . The complete pathway for the metabolism of 2-aminophenol during the degradation of nitrobenzene by Pseudomonas pseudoalcaligenes JS45 has been elucidated previously . The pathway is parallel to the catechol extradiol ring cleavage pathway, except that 2-aminophenol is the ring cleavage substrate . Here we report the elucidation of the pathway of 2-amino-4-methylphenol (6-amino-m-cresol) metabolism during the degradation of 4-nitrotoluene by Mycobacterium strain HL 4-NT-1 and the comparison of the substrate specificities of the relevant enzymes in strains JS45 and HL 4-NT-1 . The results indicate that the 2-aminophenol ring cleavage pathway in strain JS45 is not unique but is representative of the pathways of metabolism of other o-aminophenolic compounds.

Appl Environ Microbiol, 2000 Jul, 66(7), 2695 - 702
Effect of model sorptive phases on phenanthrene biodegradation: different enrichment conditions influence bioavailability and selection of phenanthrene-degrading isolates; Grosser RJ et al.; The sorption of organic contaminants by natural organic matter (NOM) often limits substrate bioavailability and is an important factor affecting microbial degradation rates in soils and sediments . We hypothesized that reduced substrate bioavailability might influence which microbial assemblages are responsible for contaminant degradation under enrichment culture conditions . Our primary goal was to characterize enrichments in which different model organic solid phases were used to establish a range of phenanthrene bioavailabilities for soil microorganisms . Phenanthrene sorption coefficients (expressed as log K(D) values) ranged from 3.0 liters kg(-1) for Amberlite carboxylic acid cation-exchange resin (AMB) to 3.5 liters kg(-1) for Biobeads polyacrylic resin (SM7) and 4.2 liters kg(-1) for Biobeads divinyl benzene resin (SM2) . Enrichment cultures were established for control (no sorptive phase), sand, AMB, SM7, and SM2 treatments by using two contaminated soils (from Dover, Ohio, and Libby, Mont.) as the initial inocula . The effects of sorption by model phases on the degradation of phenanthrene were evaluated for numerous transfers in order to obtain stable microbial assemblages representative of sorptive and nonsorptive enrichment cultures and to eliminate the effects of the NOM present in the initial inoculum . Phenanthrene degradation rates were similar for each soil inoculum and ranged from 4 to 5 micromol day(-1) for control and sand treatments to approximately 0.4 micromol day(-1) in the presence of the SM7 sorptive phase . The rates of phenanthrene degradation in the highly sorptive SM2 enrichment culture were insignificant; consequently, stable microbial populations could not be obtained . Bacterial isolates obtained from serial dilutions of enrichment culture samples exhibited significant differences in rates of phenanthrene degradation performed in the presence of SM7, suggesting that enrichments performed in the presence of a sorptive phase selected for different microbial assemblages than control treatments containing solid phase phenanthrene.

Can J Microbiol, 2000 May, 46(5), 397 - 409
Bacterial metabolism of fluorene, dibenzofuran, dibenzothiophene, and carbazole; Bressler DC et al.; Fluorene and its three heteroatomic analogs, dibenzofuran, dibenzothiophene, and carbazole, are environmental contaminants in areas impacted by spills of creosote . In addition, dibenzofuran has been used as an insecticide, and it is formed from the photolysis of chlorinated biphenyl ethers . Many biodegradation studies of dibenzofuran have considered it as a model for chlorinated dibenzofurans, which are of greater environmental concern . This paper reviews the bacterial degradation of fluorene and its analogs . These compounds are susceptible to three different modes of initial oxidation: (i) the naphthalene-like attack, in which one of the aromatic rings is oxidized to a dihydrodiol; (ii) an angular dioxygenase attack, in which the carbon bonded to the methylene group in fluorene or to the heteroatoms in the analogs, and the adjacent carbon in the aromatic ring are both oxidized; and (iii) the five-membered ring attack, in which the methylene carbon atom in fluorene or the sulfur atom in dibenzothiophene is oxidized . The metabolites, enzymology, and genetics of these transformation are summarized . Literature data are presented, indicating that the electronegativity of the atom connecting the two aromatic rings influences the attack of the angular dioxygenase . In dibenzofuran and carbazole, the connecting atoms, O and N respectively, have high electronegativities, and these compounds serve as substrates for angular dioxygenases . In contrast, the connecting atoms in dibenzothiophene and fluorene, S and C respectively, have lower electronegativities, and these atoms must be oxidized before the angular dioxygenases attack these compounds.

Biodegradation, 1999, 10(5), 331 - 40
Diversity and correlation of specific aromatic hydrocarbon biodegradation capabilities; Gulensoy N et al.; This work investigated the biodegradation capabilities of indigenous microorganisms exposed to different combinations of aromatic hydrocarbons . Considerable diversity was found in the catabolic specificity of 55 strains . Toluene was the most commonly degraded compound, followed by p-xylene, m-xylene and ethylbenzene . Strains capable of degrading o-xylene and benzene, which were the least-frequently-degraded compounds, exhibited broader biodegradation capabilities . Kappa statistics showed a significant correlation between the abilities to degrade toluene and ethylbenzene, p-xylene and m-xylene, and p-xylene and o-xylene . The ability to degrade naphthalene was correlated to the ability to degrade other alkylbenzenes, but not benzene . In addition, the inability to degrade benzene was correlated to the inability to degrade o-xylene . Factorial analysis of variance showed that biodegradation capabilities were generally broader when aromatic hydrocarbons were fed as mixtures than when fed separately . Beneficial substrate interactions included enhanced degradation of benzene, p-xylene, and naphthalene when toluene was present, and enhanced degradation of naphthalene by ethylbenzene . Such heuristic relationships may be useful to predict biodegradation patterns when bacteria are exposed to different aromatic hydrocarbon mixtures.

Eur J Biochem, 2000 Jul, 267(13), 4222 - 31
Formation of acyl radical in lipid peroxidation of linoleic acid by manganese-dependent peroxidase from Ceriporiopsis subvermispora and Bjerkandera adusta; Watanabe T et al.; Lipid peroxidation by managanese peroxidase (MnP) is reported to decompose recalcitrant polycyclic aromatic hydrocabon (PAH) and nonphenolic lignin models . To elucidate the oxidative process, linoleic acid and 13(S)-hydroperoxy-9Z,11E-octadecadienoic acid {13(S)-HPODE} were reacted with MnPs from Ceriporiopsis subvermispora and Bjerkandera adusta and the free radicals produced were analyzed by ESR . When the MnPs were reacted with 13(S)-HPODE in the presence of Mn(II), H2O2 and tert-nitrosobutane (t-NB), the ESR spectrum contained a sharp triplet of acyl radical (aN = 0.81 mT) . Formation of acyl radical was also observed in the reactions of Mn(III)-tartrate with 13(S)-HPODE and with linoleic acid, but the latter reaction occurred explosively after an induction period of around 30 min . Reactions of MnP with linoleic acid in the presence of Mn(II), H2O2 and t-NB gave no spin adducts while addition of t-NB after preincubation of linoleic acid with MnP/Mn(II)/H2O2 for 2 h gave spin adducts of carbon-centered (aN = 1.53 mT, aH = 0.21 mT) and acyl (aN = 0.81 mT) radicals . In contrast to linoleic acid, methyl linoleate and oleic acid were not peroxidized by MnP and chelated Mn(III) within a few hours, indicating that structures containing both the 1,4-pentadienyl moiety and a free carboxyl group are necessary for inducing the peroxidation in a short reaction time . These results indicate that MnP-dependent lipid peroxidation is not initiated by direct abstraction of hydrogen from the bis-allylic position during turnover but proceeds by a Mn(III)-dependent hydrogen abstraction from enols and subsequent propagation reactions involving the formation of acyl radical from lipid hydroperoxide . This finding expands the role of chelated Mn(III) from a phenol oxidant to a strong generator of free radicals from lipids and lipid hydroperoxides in lignin biodegradation.

Biotechnol Bioeng, 2000 Jul 20, 69(2), 160 - 70
Statistical analysis of nonlinear parameter estimation for Monod biodegradation kinetics using bivariate data; Knightes CD et al.; A nonlinear regression technique for estimating the Monod parameters describing biodegradation kinetics is presented and analyzed . Two model data sets were taken from a study of aerobic biodegradation of the polycyclic aromatic hydrocarbons (PAHs), naphthalene and 2-methylnaphthalene, as the growth-limiting substrates, where substrate and biomass concentrations were measured with time . For each PAH, the parameters estimated were: q(max), the maximum substrate utilization rate per unit biomass; K(S), the half-saturation coefficient; and Y, the stoichiometric yield coefficient . Estimating parameters when measurements have been made for two variables with different error structures requires a technique more rigorous than least squares regression . An optimization function is derived from the maximumlikelihood equation assuming an unknown, nondiagonal covariance matrix for the measured variables . Because the derivation is based on an assumption of normally distributed errors in the observations, the error structures of the regression variables were examined . Through residual analysis, the errors in the substrate concentration data were found to be distributed log-normally, demonstrating a need for log transformation of this variable . The covariance between ln C and X was found to be small but significantly nonzero at the 67% confidence level for NPH and at the 94% confidence level for 2MN . The nonlinear parameter estimation yielded unique values for q(max), K(S), and Y for naphthalene . Thus, despite the low concentrations of this sparingly soluble compound, the data contained sufficient information for parameter estimation . For 2-methylnaphthalene, the values of q(max) and K(S) could not be estimated uniquely; however, q(max)/K(S) was estimated . To assess the value of including the relatively imprecise biomass concentration data, the results from the bivariate method were compared with a univariate method using only the substrate concentration data . The results demonstrated that the bivariate data yielded a better confidence in the estimates and provided additional information about the model fit and model adequacy . The combination of the value of the bivariate data set and their nonzero covariance justifies the need for maximum likelihood estimation over the simpler nonlinear least squares regression .

Aquat Toxicol, 2000 Jul 1, 49(4), 289 - 304
In vivo and in vitro metabolism and organ distribution of nonylphenol in Atlantic salmon (Salmo salar); Arukwe A et al.; In the environment, nonylphenol (NP) occurs predominantly as a degradation product of nonylphenol ethoxylate (NPE) . They can be found in many types of products including detergents, plastics, emulsifiers, pesticides, and industrial and consumer cleaning products . As a consequence of their use in a variety of products, they are quite common in rivers and other aquatic environments that receive sewage discharges . Because of its enhanced resistance towards biodegradation, toxicity, estrogenic effects, and ability to bioaccumulate in aquatic organisms NP has been regarded as the most critical metabolite of APEs . We have studied the in vivo and in vitro metabolism and organ distribution of NP in juvenile salmon . Fish were exposed in vivo to waterborne {3H}-4-n-NP for a period up to 72 h or were administered a single oral dose of {3H}-4-n-NP . In vitro biotransformation of NP was studied by exposure of cultured salmon hepatocytes to {3H}-4-n-NP in the presence or absence of a CYP1A-inducer, beta-naphthoflavone (betaNF) . Our results show that 4-n-NP was mainly metabolized in vivo, to its corresponding glucuronide conjugates and hydroxylates . The major route of excretion was the bile . The half-life of residues in carcass and muscle was between 24 and 48 h in both waterborne and dietary exposure . In whole body autoradiography, intragastric administered {3H}-4-n-NP was mainly present in the gastrointestinal tract and bile . NP-derived radioactivity in fish exposed via water was more evenly distributed in the organs compared to intragastric exposure and were observed in the intestinal contents, liver, kidney, gills, skin, abdominal fat and brain . In vitro pretreatment of hepatocytes with betaNF had no effect on rates or patterns of NP biotransformation . The in vitro metabolic rate of NP were 118 pmol NP metabolized/h/0.5x10(6) cells without betaNF, and 98 pmol NP metabolized/h/0.5x10(6) cells when betaNF was added to the culture medium.

Biomed Environ Sci, 2000 Mar, 13(1), 56 - 68
Biological degradation of some organic compounds enrolled in paper industry--a pollution prevention approach; Wahaab RA; Evaluation of the elimination and the "ultimate" biodegradation by aerobic microorganisms of some organic compounds commonly used in paper manufacturing technology was investigated . Biodegradation lines of nine organic compounds were determined as percentage removal of chemical oxygen demand (COD) over 7 days incubation . The results of the biodegradability test clearly revealed that some of the organic compounds under investigation are highly biodegradable, while others rank from fairly to even non-biodegradable . Significant biodegradation results were recorded for anti-coating ester (95.0%), basoplast 200D (85.3%) and basoplast PR 8050 (87.6%) . A bleaching agent (formamidin-sulfinic acid), ukanol BSA and solidurit KM demonstrate moderate biodegradation results of 62.1%, 76.2% and 69.8%, respectively . Poor biodegradation results for Hedifix M/35 (12.7%), basazol orange (34.9%) and basazol brown (29.0%) were recorded . Accordingly, appropriate precaution should be taken into consideration when using these compounds for industrial applications.

Curr Opin Microbiol, 2000 Jun, 3(3), 257 - 62
Detoxification of reactive intermediates during microbial metabolism of halogenated compounds; van Hylckama Vlieg JE et al.; The reactivity and toxicity of metabolic intermediates that are generated by initial biotransformation reactions can be a major limiting factor for biodegradation of halogenated organic compounds . Recent work on the conversion of haloalkanes, chloroaromatics and chloroethenes indicates that microorganisms may become less sensitive to toxic effects either by using novel pathways that circumvent the generation of reactive intermediates or by producing modified enzymes that decrease the toxicity of such compounds.

Schweiz Arch Tierheilkd, 2000 May, 142(5), 263 - 7
Exposure of rainbow trout (Oncorhynchus mykiss) to nonylphenol is associated with an increased chloride cell fractional surface area; Stoffel MH et al.; Nonylphenol is a biodegradation product of a widely used group of non-ionic detergents . Because of its ubiquitous distribution and persistence, nonylphenol is present in surface waters as a pollutant . Little is known about its biological effects at environmentally relevant concentrations other than its action as a xenoestrogen . The goal of the present paper was to study the trout gill surface epithelium as the major interface between fish and water in view of possible morphological alterations due to exposure to nonylphenol . Rainbow trout were intermittently exposed to 10 micrograms/l nonylphenol and gill samples from experimental and control animals were investigated by scanning electron microscopy . Gill surface epithelium was scrutinised for changes in chloride cell density and their status regarding cell surface modifications . In addition, chloride cell fractional surface area (CCFA) was determined by morphometrical methods . Statistical analysis revealed a highly significant increase of CCFA in animals exposed to nonylphenol as compared to control animals (P = 0.0001) . Semi-quantitative assessment of the other parameters suggested a higher chloride cell density and a larger proportion of chloride cells bearing microvilli . Taken together, these results provide evidence that exposure of trout to nonylphenol is associated with a substantial increase in the active interface of chloride cells with water . We interpret these findings as being a means to further the fish's capacity for calcium exchange.

J Biomater Sci Polym Ed, 2000, 11(3), 301 - 18
Synthesis, characterization, biodegradation, and drug delivery application of biodegradable lactic/glycolic acid polymers: I . Synthesis and characterization; Wang N et al.; A series of lactic/glycolic acid polymers with various molar ratios of lactic to glycolic acid and various molecular weights were synthesized using the ring-opening polymerization method . The polymerization conditions for the lactic/glycolic acid polymer synthesis were as follows: 150 degrees C, 700 microm Hg, 3 h, 0.03 wt% of catalyst (stannous 2-ethyl-hexanoate) concentration . The molecular weight of these polymers was controlled by using a molecular weight controller, lauryl alcohol . The synthesized polymers have been characterized with respect to polymer composition, molecular weight, inherent viscosity, and glass transition temperature . The characterization experiments show a good correlation between the polymer compositions and the feed ratios of lactic to glycolic acid . The molecular weight of the lactic/glycolic polymers, ranging from 10,876 to 166,630 D and the intrinsic viscosity of the polymers, ranging from 0.16 to 0.86 dl g(-1), are controlled by the amount of molecular weight controller used . The effect of the amount of the molecular weight controller on the polymer molecular weight and the polymer inherent viscosity was studied . Results indicate that the molecular weight and inherent viscosity of the polymers have a log-log linear relationship with the amount of molecular weight controller used . The lactic/glycolic acid polymers are amorphous, glassy, and transparent . The glass transition temperature of the polymers range from 21.95 to 51.29 degrees C, depending on the polymer molecular weight and the composition.

Adv Drug Deliv Rev, 1998 May 4, 31(3), 287 - 301
Protein release from gelatin matrices; Ikada Y et al.; Gelatin is a denatured, biodegradable protein obtained by acid and alkaline processing of collagen . This processing affects the electrical nature of collagen, yielding gelatin with different isoelectric points (IEPs) . When mixed with positively or negatively charged gelatin, an oppositely charged protein will ionically interact to form a polyion complex . This review article describes protein release from charged gelatin matrices on the basis of this polyion complexation . The biodegradable hydrogel matrices are prepared by chemical crosslinking of acidic or basic gelatin and are enzymatically degraded in the body with time . The degradation is controllable by changing the extent of crosslinking, which, in turn, produces hydrogels with different water contents . The time course of protein release is in good accordance with the rate of hydrogel degradation . It is very likely that the protein drug complexed with gelatin hydrogel is released as a result of its biodegradation . This gelatin hydrogel system releases the protein drug under maintenance of biological activity . This article will focus on experimental data that sustained release of growth factor from the gelatin hydrogels is very effective in exerting the biological functions of the growth factor.

Adv Drug Deliv Rev, 1997 Oct 13, 28(1), 5 - 24
Biodegradation and biocompatibility of PLA and PLGA microspheres; Shive MS et al.; A fundamental understanding of the in vivo biodegradation phenomenon as well as an appreciation of cellular and tissue responses which determine the biocompatibility of biodegradable PLA and PLGA microspheres are important components in the design and development of biodegradable microspheres containing bioactive agents for therapeutic application . This chapter is a critical review of biodegradation, biocompatibility and tissue/material interactions, and selected examples of PLA and PLGA microsphere controlled release systems . Emphasis is placed on polymer and microsphere characteristics which modulate the degradation behaviour and the foreign body reaction to the microspheres . Selected examples presented in the chapter include microspheres incorporating bone morphogenetic protein (BMP) and leuprorelin acetate as well as applications or interactions with the eye, central nervous system, and lymphoid tissue and their relevance to vaccine development . A subsection on nanoparticles and nanospheres is also included . The chapter emphasizes biodegradation and biocompatibility; bioactive agent release characteristics of various systems have not been included except where significant biodegradation and biocompatibility information have been provided.

Chemosphere, 2000 Sep, 41(5), 743 - 9
Degradation of silicone polymer in a field soil under natural conditions; Lehmann RG et al.; Silicone polymers (PDMS = polydimethylsiloxane) are used in numerous consumer and industrial products . Our previous work showed that they will degrade in soil under laboratory conditions . This paper investigates PDMS degradation in the field . Four soil plots (each 2.44 m x 2.44 m) in Michigan were sprayed in May, 1997, with aqueous emulsion to achieve nominal soil PDMS concentrations of 0 (control), 215 (low), 430 (medium), and 860 (high) microg/g . Over the following summer, soil cores (0-5 and 5-10 cm) were collected every two weeks and analyzed for decrease in-total soil PDMS, and decrease in molecular weight of remaining PDMS . PDMS concentrations decreased 50% in 4.5, 5.3, and 9.6 weeks for the low, medium, and high treatments, respectively . Degradation rates were 0.26 (low), 0.44 (medium), and 0.44 (high) g PDMS/m2 day, indicating that degradation capacity of the soil was exceeded by the High treatment . Dimethylsilanediol (DMSD), the main degradation product, was detected in most samples at <5% of original PDMS . This is consistent with laboratory data showing biodegradation and volatilization of DMSD . Deeper sampling (to 20 cm) found only trace amounts of DMSD, and minor downward movement of the polymer . Respraying and subsequent analysis of one plot with a medium treatment in late August showed slow PDMS degradation during the cool, wet fall, followed by a 40% decrease over winter and extensive degradation during the summer of 1998 . The study thus shows that PDMS will degrade under field conditions as predicted from laboratory experiments.

Chemosphere, 2000 Sep, 41(5), 645 - 51
An automated test for measuring polymer biodegradation; Calmon A et al.; The biodegradability of polymer materials as evaluated by the modified Sturm test is labor-intensive, cumbersome and costly and also tends to cumulate errors . An automated system for the measurement of carbon dioxide would overcome many of these disadvantages . We describe here a method in which CO2 was determined by IR spectroscopy . We compared the results with those from trapping CO2 in a solution of barium hydroxide (Ba(OH)2) followed by manual titration . The automated system was more reproducible, less costly and more compact . The automated system could also be employed to measure the biodegradability of other substances such as oils and detergents.

Appl Environ Microbiol, 2000 Jun, 66(6), 2652 - 7
Characterization of metabolites during biodegradation of hexahydro-1, 3,5-trinitro-1,3,5-triazine (RDX) with municipal anaerobic sludge; Hawari J et al.; The biodegradation of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) in liquid cultures with municipal anaerobic sludge showed that at least two degradation routes were involved in the disappearance of the cyclic nitramine . In one route, RDX was reduced to give the familiar nitroso derivatives hexahydro-1-nitroso-3,5-dinitro-1,3, 5-triazine (MNX) and hexahydro-1,3-dinitroso-5-nitro-1,3,5-triazine (DNX) . In the second route, two novel metabolites, methylenedinitramine {(O(2)NNH)(2)CH(2)} and bis(hydroxymethyl)nitramine {(HOCH(2))(2)NNO(2)}, formed and were presumed to be ring cleavage products produced by enzymatic hydrolysis of the inner C---N bonds of RDX . None of the above metabolites accumulated in the system, and they disappeared to produce nitrous oxide (N(2)O) as a nitrogen-containing end product and formaldehyde (HCHO), methanol (MeOH), and formic acid (HCOOH) that in turn disappeared to produce CH(4) and CO(2) as carbon-containing end products.

Appl Environ Microbiol, 2000 Jun, 66(6), 2372 - 7
Anaerobic-aerobic process for microbial degradation of tetrabromobisphenol A; Ronen Z et al.; Tetrabromobisphenol A (TBBPA) is a flame retardant that is used as an additive during manufacturing of plastic polymers and electronic circuit boards . Little is known about the fate of this compound in the environment . In the current study we investigated biodegradation of TBBPA, as well as 2,4,6-tribromophenol (TBP), in slurry of anaerobic sediment from a wet ephemeral desert stream bed contaminated with chemical industry waste . Anaerobic incubation of the sediment with TBBPA and peptone-tryptone-glucose-yeast extract medium resulted in a 80% decrease in the TBBPA concentration and accumulation of a single metabolite . This metabolite was identified by gas chromatography-mass spectrometry (GC-MS) as nonbrominated bisphenol A (BPA) . On the other hand, TBP was reductively dehalogenated to phenol, which was further metabolized under anaerobic conditions . BPA persisted in the anaerobic slurry but was degraded aerobically . A gram-negative bacterium (strain WH1) was isolated from the contaminated soil, and under aerobic conditions this organism could use BPA as a sole carbon and energy source . During degradation of BPA two metabolites were detected in the culture medium, and these metabolites were identified by GC-MS and high-performance liquid chromatography as 4-hydroxybenzoic acid and 4-hydroxyacetophenone . Both of those compounds were utilized by WH1 as carbon and energy sources . Our findings demonstrate that it may be possible to use a sequential anaerobic-aerobic process to completely degrade TBBPA in contaminated soils.

Biochemistry, 2000 May 9, 39(18), 5303 - 11
Recruitment of a double bond isomerase to serve as a reductive dehalogenase during biodegradation of pentachlorophenol; Anandarajah K et al.; Tetrachlorohydroquinone dehalogenase catalyzes the replacement of chlorine atoms on tetrachlorohydroquinone and trichlorohydroquinone with hydrogen atoms during the biodegradation of pentachlorophenol by Sphingomonas chlorophenolica . The sequence of the active site region of tetrachlorohydroquinone dehalogenase is very similar to those of the corresponding regions of maleylacetoacetate isomerases, enzymes that catalyze the glutathione-dependent isomerization of a cis double bond in maleylacetoacetate to the trans configuration during the catabolism of phenylalanine and tyrosine . Furthermore, tetrachlorohydroquinone dehalogenase catalyzes the isomerization of maleylacetone (an analogue of maleylacetoacetate) at a rate nearly comparable to that of a bona fide bacterial maleylacetoacetate isomerase . Since maleylacetoacetate isomerase is involved in a common and presumably ancient pathway for catabolism of tyrosine, while tetrachlorohydroquinone dehalogenase catalyzes a more specialized reaction, it is likely that tetrachlorohydroquinone dehalogenase arose from a maleylacetoacetate isomerase . The substrates and overall transformations involved in the dehalogenation and isomerization reactions are strikingly different . This enzyme provides a remarkable example of Nature's ability to recruit an enzyme with a useful structural scaffold and elaborate upon its basic catalytic capabilities to generate a catalyst for a newly needed reaction.

Ann N Y Acad Sci, 2000 Apr, 905, 177 - 87
Mechanisms of lysolipid phosphate effects on cellular survival and proliferation; Goetzl EJ et al.; The specificity of cellular effects of lysolipid phosphate (LLP) growth factors is determined by binding to endothelial differentiation gene-encoded G protein-coupled receptors (EDG Rs), which transduce diverse proliferative and effector signals . The primary determinants of cellular responses to LLPs are the generative and biodegradative events, which establish steady-state concentrations of each LLP at cell surfaces, and the relative frequency of expression of each EDG R . There are major differences among types of cells in the net effective generation of the LLPs, lysophosphatidic acid (LPA) and sphingosine 1-phosphate (S1P), and in their profile of expression of EDG Rs . The less well characterized secondary determinants of cellular specificity of LLPs are high-affinity binding proteins with carrier and cell-presentation functions, cell-selective regulators of expression of EDG Rs, and cellular factors that govern coupling of EDG Rs to G protein transductional pathways . The roles of components of the LLP-EDG R system in normal physiology and disease processes will be definitively elucidated only after development of animal models with biologically meaningful alterations in genes encoding EDG Rs and the discovery of potent and selective pharmacological probes.

J Biomed Mater Res, 2000 Jul, 51(1), 136 - 45
In vivo compatibility and degradation of crosslinked gelatin gels incorporated in knitted Dacron; Kuijpers AJ et al.; Gelatin gels were applied to porous Dacron meshes with the aim of using these gels for local drug delivery . In this article, the biocompatibility and degradation of gelatin gels with different crosslink densities applied in Dacron were studied in vivo by subcutaneous implantation in rats . Dacron discs were treated with carbon dioxide gas plasma to improve hydrophilicity, and subsequently impregnated with gelatin type B . The gelatin samples were crosslinked to different extents using various amounts of water-soluble carbodiimide (EDC) and N-hydroxysuccinimide (NHS) . After 6 h, 2, 5, and 10 days, and 3, 6, and 10 weeks of postimplantation, the tissue reactions and biodegradation were studied by light microscopy . The early reaction of macrophages and polymorphonuclear cells to crosslinked gelatin was similar to or milder than Dacron . Giant cell formation was predominantly aimed at Dacron fibers and was markedly reduced in the presence of a crosslinked gelatin coating . At week 10 of implantation, the crosslinked gelatin gels were still present in the Dacron matrix . The gelatin degradation was less for samples with the highest crosslink density . The gelatin gel with the lowest crosslink density showed clear cellular ingrowth, starting after 6 weeks of implantation . The intermediate and high crosslinked gelatin gels showed little or no ingrowth . In these gels, giant cells were involved in the phagocytosis of gelatin parts at week 10 . Application of carbodiimide crosslinked gelatin gels in Dacron is suitable for medical applications because of the good biocompatibility of the gels and the possibility of adapting the degradation rate of gelatin to a specific application .

Biomaterials, 2000 Jun, 21(12), 1247 - 58
A new peptide-based urethane polymer: synthesis, biodegradation, and potential to support cell growth in vitro; Zhang JY et al.; A novel non-toxic biodegradable lysine-di-isocyanate (LDI)-based urethane polymer was developed for use in tissue engineering applications . This matrix was synthesized with highly purified LDI made from the lysine diethylester . The ethyl ester of LDI was polymerized with glycerol to form a prepolymer . LDI-glycerol prepolymer when reacted with water foamed with the liberation of CO2 to provide a pliable spongy urethane polymer . The LDI-glycerol matrix degraded in aqueous solutions at 100, 37, 22, and 4 degrees C at a rate of 27.7, 1.8, 0.8, and 0.1 mM per 10 days, respectively . Its thermal stability in water allowed its sterilization by autoclaving . The degradation of the LDI-glycerol polymer yielded lysine, ethanol, and glycerol as breakdown products . The degradation products of LDI-glycerol polymer did not significantly affect the pH of the solution . The glass transition temperature (Tg) of this polymer was found to be 103.4 degrees C . The physical properties of the polymer network were found to be adequate to support the cell growth in vitro, as evidenced by the fact that rabbit bone marrow stromal cells (BMSC) attached to the polymer matrix and remained viable on its surface . Culture of BMSC on LDI-glycerol matrix for long durations resulted in the formation of multilayered confluent cultures, a characteristic typical of bone cells . Furthermore, cells grown on LDI-glycerol matrix did not differ phenotypically from the cells grown on the tissue culture polystyrene plates as assessed by the cell growth, and expression of mRNA for collagen type I, and transforming growth factor-beta1 (TGF-beta1) . The observations suggest that biodegradable peptide-based urethane polymers can be synthesized which may pave their way for possible use in tissue engineering applications.

J Environ Sci Health B, 2000 May, 35(3), 337 - 46
Biodegradation of alpha and beta isomers of endosulphan and endosulphan sulphate in Indian soils; Shalini-Singh et al.; The degradation of alpha and beta isomers of endosulphan and endosulphan sulphate in four sterilized and non sterilized Indian soils under laboratory conditions was studied . Degradation was found to be more in non-sterilized as compared to the sterilized soil . The half life of alpha-endosulphan, beta-endosulphan and endosulphan sulphate was found to be 136.8, 273 and 301 days in sterilized Alfisol and 55, 256 and 277 days in non-sterilized Alfisol,respectively . Alpha-endosulphan degraded more readily than beta-endosulphan and endosulphan sulphate under both sterilized and non-sterilized soil conditions.

J Tongji Med Univ, 1998, 18(4), 257 - 61
Biodegradation of tricalcium phosphate ceramics by osteoclasts; Zheng Q et al.; Biodegradation of tricalcium phosphate (TCP) ceramics was observed through mixed culture of osteoclasts and TCP discs in vitro in this study . Osteoclasts were isolated from newborn SD rat's marrow of long bone and cultured on TCP discs . The culture terminated at the 48th h and 96th h respectively . Under an inverted microscope, the osteoclasts imparted round or oval body with multinuclear and many thin processes . These cells were positively stained for tartrate-resistance acid phosphatase (TRAP) . Scanning electron microscope showed that many resorption lacunae on TCP disc surface and their diameters were smaller than 20 microns . Osteoclasts were located in the lacunae . At the 96th h, the resorption lacunae become larger and osteoclasts showed degeneration . It is suggested that osteoclasts possess ability to re-absorb TCP ceramics under in vitro culturing condition.

Ecotoxicol Environ Saf, 2000 May, 46(1), 34 - 40
Nonylphenol affects the granulation pattern of epidermal mucous cells in rainbow trout, Oncorhynchus mykiss; Burkhardt-Holm P et al.; Nonylphenol is a biodegradation product of nonionic surfactants and has recently attracted considerable attention due to its estrogenic potential . Sexually mature male rainbow trout were repeatedly exposed (one to four periods of 10 days each) to environmentally relevant concentrations of nonylphenol (1 microg/L, 10 microg/L) and for comparison, trout were injected with estradiol . Since estrogens are known to induce structural changes within the fish skin, a similar effect of xenobiotics with estrogen-like activity was assumed . Samples of skin were evaluated by means of light and electron microscopy and histochemistry . In trout exposed to nonylphenol and to estradiol, the structure of the epidermis was altered: an irregular overall architecture was often accompanied by detached pavement cells, vacuolation of the cytoplasm, and severely deformed cell nuclei . However, the granulation pattern of the mucous cells was influenced exclusively after exposition to nonylphenol . The number of large and irregularly shaped mucosomes depended more on the exposure period than on the concentration of nonylphenol . Furthermore, this alteration has not yet been reported for any other pollutant or stressor and, thus, can be classified as an effect that would strongly indicate exposure to nonylphenol .

Sci Justice, 2000 Jan-Mar, 40(1), 15 - 20
The biodegradation of the fabric of soldiers' uniforms; Was-Gubala J et al.; A study to determine the changes in the morphological structure of woollen fabric and fibres of military uniforms, after burial in biologically active soil for a particular period of time . The analysis of fabric and fibres was performed by means of organoleptic and microscopic observations . The final decay of the fabric of soldiers' uniforms took place after 5-6 weeks burial in the standardised bioactive soil . The changes of the morphological structure of fabric undergoing the process of biodegradation depended mainly on the duration of their burial in the soil.

Arch Environ Contam Toxicol, 2000 Jul, 39(1), 60 - 5
Soil dissipation of diuron, chlorotoluron, simazine, propyzamide, and diflufenican herbicides after repeated applications in fruit tree orchards; Rouchaud J et al.; In a pear tree orchard planted on loam soil, each plot was treated in April 1998 with either one of the ureas diuron or chlorotoluron, or triazine simazine herbicides applied at 3, 4, and 2 kg AI ha(-1), respectively . Some plots had not been previously treated with one of these herbicides . Other plots had been treated annually during the past 12 years with the same herbicide . One herbicide, and always the same, was thus applied to each plot . In the plots treated for the first time with either diuron, chlorotoluron, or simazine, the soil half-lives of these herbicides in the 0-10 cm surface soil layer were 81, 64, and 59 days, respectively . In the plots treated with the same herbicide for 12 years, the corresponding soil half-lives were 37, 11, and 46 days . Diuron thus produced a moderately enhanced biodegradation, chlorotoluron a high one, and simazine a low but significant one . In another pear tree orchard planted on sandy loam soil, each plot was treated in April 1998 with one of the amide propyzamide (1.25 or 1.0 AI kg ha(-1)) or diflufenican (250 g AI ha(-1)) herbicides . In the plots not previously treated with propyzamide, the propyzamide soil half-life was the same for both doses, i.e., about 30 days . In the plots treated annually for 3 or 14 years with propyzamide, the soil half-life was 12 and 10 days, respectively . In the plots treated for the first time with diflufenican and in those treated annually with diflufenican for 3 years, the diflufenican soil half-life was the same, i.e., 65 days . Propyzamide thus already showed a highly accelerated biodegradation after 3 years of repeated annual applications . Diflufenican, however, did not show enhanced biodegradation after 3 years of repeated annual applications.

Chemosphere, 2000 Jun, 40(12), 1389 - 97
A chemostat system for investigating pesticide biodegradation in continuous mixed bacteria cultures originating from surface water; Schrap SM et al.; To be able to predict the degradation (rate) of organic chemicals (e.g . pesticides) in the field, knowledge of the environmental conditions that are of influence on the degradation process are of importance . In the present study an experimental system is described which is used to study the degradation of organic pollutants in mixed bacteria cultures originating from surface water With this system the degradation of compounds can be followed for relatively long experimental periods (months) . In addition, it is possible to vary different environmental parameters in order to investigate their influences on the degradation of the chemical . These preliminary experiments show that growth and 'composition' of the bacteria culture have comparable patterns in parallel experiments . The first order degradation rate constant for the test compound dichloran, as calculated from these experiments under these circumstances, is about 0.002 h(-1).

Vet Q, 2000 Apr, 22(2), 112 - 6
Assessment of health risks of large semi-wild herbivores in urbanized areas; van Essen GJ et al.; The health risks for both domestic animals and humans caused by large herbivores in self-sustaining ecosystems are largely unknown . The aim of this article is to make an inventory of these risks, to explore ways to manage them in practice, and to make recommendations for the quantification of risks . Potential hazards from herbivores in and around Europe are listed using the data of the OIE (Office International des Epizooties) . The desired health status and the implementation of control or surveillance measures are important factors when assessing the risks . Results indicate that a regular yearly system of health monitoring of herbivores is necessary . To get more insight into the importance of certain risks (Infectious Bovine Rhinotracheitis, biodegradation of carrion in the field) epidemiological investigations have to be carried out to assess the risk of transmission in different situations (with or without intervention) . Analysing and managing risks enable decision-makers to formulate the conditions for the development of nature reserves . In Europe more has to be done to increase the quality of nature in terms of de-fragmentation and de-isolation, but regulations concerning the health of large herbivores also have to be improved.

Arch Environ Contam Toxicol, 2000 May, 38(4), 439 - 45
Influence of petroleum hydrocarbon contamination on microalgae and microbial activities in a long-term contaminated soil; Megharaj M et al.; Petroleum hydrocarbons are widespread environmental pollutants . Although biodegradation of petroleum hydrocarbons has been the subject of numerous investigations, information on their toxicity to microorganisms in soil is limited, with virtually no work conducted on soil algae . We carried out a screening experiment for total petroleum hydrocarbons (TPH) and their toxicity to soil algal populations, microbial biomass, and soil enzymes (dehydrogenase and urease) in a long-term TPH-polluted site with reference to an adjacent unpolluted site . Microbial biomass, soil enzyme activity, and microalgae declined in medium to high-level (5,200-21,430 mg kg(-1) soil) TPH-polluted soils, whereas low-level (<2,120 mg kg(-1) soil) pollution stimulated the algal populations and showed no effect on microbial biomass and enzymes . However, inhibition of all the tested parameters was more severe in soil considered to have medium-level pollution than in soils that were highly polluted . This result could not be explained by chemical analysis alone . Of particular interest was an observed shift in the species composition of algae in polluted soils with elimination of sensitive species in the medium to high polluted soils . Also, an algal growth inhibition test carried out using aqueous eluates prepared from polluted soils supported these results . Given the sensitivity of algae to synthetic pollutants, alteration in the algal species composition can serve as a useful bioindicator of pollution . The results of this experiment suggest that chemical analysis alone is not adequate for toxicological estimations and should be used in conjunction with bioassays . Furthermore, changes in species composition of algae proved to be more sensitive than microbial biomass and soil enzyme activity measurements.

Prikl Biokhim Mikrobiol, 2000 Mar-Apr, 36(2), 178 - 88
{Microbial degradation of components of waste water from phenol-producing industry}; Singirtsev IN et al.; Processes of aerobic biodegradation of components of phenol production sewage (phenol, acetophenone, dimethylphenylcarbinol, cumene hydroperoxide, alpha-methylstyrene, benzoate, and p-hydroxybenzoate) by bacterial strains obtained from the collection of Saratov Institute of Biocatalysis were studied . The metabolic reactions were shown to be oxidative and have a common catabolic sequence (cumene hydroperoxide-dimethylphenyl-carbinol alpha-methylstyrene-acetophenone-phenyl acetate-phenol-pyrocatechol-aromatic ring breakage) . Benzoate and p-hydroxybenzoate were degraded through the formation of pyrocatechol and protocatechuate, respectively . Metabolic pathways were similar in model mixtures of components and sewage samples.

FEMS Microbiol Lett, 2000 May 1, 186(1), 27 - 34
Biodegradation of diethyl phthalate in soil by a novel pathway; Cartwright CD et al.; Biodegradation of diethyl phthalate (DEP) has been shown to occur as a series of sequential steps common to the degradation of all phthalates . Primary degradation of DEP to phthalic acid (PA) has been reported to involve the hydrolysis of each of the two diethyl chains of the phthalate to produce the monoester monoethyl phthalate (MEP) and then PA . However, in soil co-contaminated with DEP and MeOH, biodegradation of the phthalate to PA resulted in the formation of three compounds, in addition to MEP . These were characterised by gas chromatography-electron ionisation mass spectrometry and nuclear magnetic resonance as ethyl methyl phthalate, dimethyl phthalate and monomethyl phthalate, and indicated the existence of an alternative pathway for the degradation of DEP in soil co-contaminated with MeOH . Transesterification or demethylation were proposed as the mechanisms for the formation of the three compounds, although the 7:1 ratio of H(2)O to MeOH means that transesterification is unlikely.

Microbiol Res, 2000 Mar, 154(4), 289 - 96
Formaldehyde and methanol biodegradation with the methylotrophic yeast Hansenula polymorpha in a model wastewater system; Kaszycki P et al.; In search of the optimal way to reduce the hazards of environmental contamination by formaldehyde (FD) and methanol the use of unconventional yeasts is proposed as exemplified by the methylotrophic yeast Hansenula polymorpha . In a very simplified environment of a model wastewater solution, H . polymorpha cells were able to grow on, and metabolize formaldehyde and methanol, applied as sole carbon sources, at concentrations typical for wastewaters of the chemical industry . Several experimental conditions were tested for cell growth and biodegradation kinetics . It was found that the yeast culture inoculated at low cell density was able to grow on initial FD levels up to 400mg/l and the biomass yield was dependent on both, the amount of total carbon added and the physiological state of the cells . When high density of pre-adapted cell culture was used, the methylotrophs were fully viable and able to degrade formaldehyde present at initial concentrations up to 700 mg/l . The maximum limiting FD consumption rate was determined as approx . 400 mg/1 per hour . Methanol, at concentrations up to 2%, was easily utilized and did not have a negative effect on cell growth and respiration . It is suggested that in real wastewaters the eukaryotic microorganisms--in contrast to bacteria--might reveal greater adaptation potential to toxic levels of formaldehyde as well as to other wastewater constituents.

Skin Pharmacol Appl Skin Physiol, 2000 Mar-Apr, 13(2), 93 - 103
Cutaneous inflammation and proliferation in vitro: differential effects and mode of action of topical glucocorticoids; Lange K et al.; The nonhalogenated double ester of prednisolone, prednicarbate (PC), is the first topical glucocorticoid with an improved benefit/risk ratio verified clinically and in vitro . To evaluate if this is due to unique characteristics of this steroid, a new compound created according to an identical concept, prednisolone 17-ethylcarbonate, 21-phenylacetate (PEP), and the new halogenated monoester desoximetasone 21-cinnamate (DCE) were tested and compared to PC, desoximetasone (DM) and betamethasone 17-valerate (BMV) . Isolated foreskin keratinocytes served for in vitro investigations of anti-inflammatory processes in the epidermis, fibroblasts of the same origin were used to investigate the atrophogenic potential . Inflammation was induced by TNFalpha, resulting in an increased interleukin 1alpha (Il-1alpha) synthesis . As quantified by ELISA, all drugs significantly reduced Il-1alpha production . But PC and BMV appeared particularly potent, followed by DM and the two new congeners, which revealed minor anti-inflammatory activity . Glucocorticoid esters including PEP are rapidly degraded in keratinocytes (85% within 12 h) . Hence, a ribonuclease protection assay of Il-1alpha mRNA was performed allowing short incubation times and thus minimizing biodegradation . This assay confirmed the anti-inflammatory potency of native PC and BMV . In contrary DCE and PEP did not reduce Il-1alpha mRNA to a significant extent . Therefore PEP acts as a prodrug only . In fibroblasts, Il-1alpha and Il-6 syntheses indicate proliferation and inflammation, respectively . Whereas PC and PEP inhibited Il-1alpha and Il-6 production in fibroblasts only to a minor extent, cytokine synthesis was strongly affected by the conventional glucocorticoids BMV and DM, but also by DCE . The minor unwanted effect of PC and PEP on fibroblasts was also reflected by their low influence on cell proliferation as derived from (3)H-thymidine incorporation . Again, more pronounced antiproliferative features were seen with the halogenated glucocorticoids . In the following, the correlation between antiphlogistic effects in keratinocytes (suppression of Il-1alpha) and antiproliferative effects in fibroblasts (suppression of Il-1alpha and Il-6; (3)H-thymidine incorporation) was analyzed . Here, PC is revealed as the only glucocorticoid with an improved benefit/risk ratio . Native PEP is shown to be almost ineffective and DCE presents exactly the opposite features of PC . It is tempting to speculate if this is due to different glucocorticoid receptor subtypes or different signaling pathways in keratinocytes and fibroblasts .

Biotechnol Bioeng, 2000 May 20, 68(4), 422 - 9
Endogenous model state and parameter estimation from an extensive batch experiment; Keesman KJ et al.; In this paper an extensive batch experiment of endogenous process behavior in an aerobic biodegradation process is presented . From these experimental data, comprising measurements of MLVSS (mixed liquor volatile suspended solids) and respiration rate, in a first step the states and unknown parameters in a four-compartmental model are reconstructed analytically . Subsequently, for a selected set of states and parameters, using the results of the previous step, a recursive state estimation procedure, in particular an Extended Kalman filter-based observer, is applied to deal with the noise properties of the data appropriately . From this it appears that the initially proposed model structure, and especially the hydrolysis term, has to be modified .

Orthopade, 2000 Feb, 29(2), 112 - 9
{Chondrocyte transplantation in PGLA/polydioxanone fleece}; Perka C et al.; The transplantation of chondrogenic cells in a supportive carrier structure proved to be a promising alternative for the treatment of cartilage defects . In the study presented we focused on the transplantation of allogeneic chondrocytes in a biodegradable polymer scaffold (PGLA/Polydioxanon) in articular cartilage defects in a rabbit defect model . Isolated allogeneic chondrocytes embedded in a PGLA polymer scaffold were transplanted into osteochondrogenic defects of the patellar groove and compared with empty defects and transplants of polymer scaffolds without cells . The histological and histochemical analysis was performed after 4 and 12 weeks . The transplant integration and the architecture of the newly formed cartilage were evaluated with a semiquantitative score . After 4 weeks the development of a hyaline-like cartilage tissue of the cell-polymer-transplants was observed, after 12 weeks the defects were nearly completely filled with hyaline-like cartilage . The biodegradation of the polymer construct did not affect the histological structure of the transplant area . Defects of the groups with empty defect and polymer transplants without cells revealed no or insufficient healing indices . The study demonstrated that biodegradable polymers served as suitable carriers for the chondrocyte transplantation, which is due to the in-vitro establishment of a semi-solid cartilage transplant and the resulting effective transplant fixation into the defect . In-vivo the polymer cell transplants seem to provide a supportive microenvironment for the development of hyaline cartilage . The controlled release of morphogenic factors or bioactive molecules and the use of pluripotent mesenchymal progenitor cells opens new perspectives for the optimization of cartilage repair procedures.

Chemosphere, 2000 May-Jun, 40(9-11), 943 - 9
Degradation half-life times of PCDDs, PCDFs and PCBs for environmental fate modeling; Sinkkonen S et al.; Literature search of the knowledge on the degradation of persistent organic pollutants (POPs) in environmental compartments air, water, soil and sediment was done in purpose to find properties of POPs of interest for modeling . One degradation process, hydrolysis (chemical degradation), was omitted as negligibly slow for POPs studied . The other two, photolysis and biodegradation processes, were considered separately in purpose to develop estimation procedures . The estimates can be given as pseudo first-order rate constants kP for photolysis and kB for biodegradation . For each compartment, an overall degradation rate is k(tot) = kP + kB and lifetime t(1/2) = ln 2/k(tot) . The latter values, lifetimes in each compartment, will be used as input parameters to the Baltic Sea model.

Lett Appl Microbiol, 2000 Feb, 30(2), 155 - 60
Low surfactant concentration increases fungal mineralization of a polychlorinated biphenyl congener but has no effect on overall metabolism; Beaudette LA et al.; Three white rot fungi were compared for their ability to attack polychlorinated biphenyl (PCB) congeners in the presence and absence of the non-ionic Triton X-100 or the anionic Dowfax 8390 surfactants at half their critical micelle concentrations . Neither surfactant affected PCB biodegradation monitored by gas chromatography but the release of 14CO2 from 2,4',5-{U-14C}trichlorobiphenyl by Trametes versicolor was stimulated 12% by Triton X-100 . Since mineralization is the complete metabolism of the congener and biodegradation was measured as substrate disappearance, Triton X-100 is proposed to aid intracellular solubilization of 2,4',5-trichlorobiphenyl for complete oxidation by T . versicolor.

Biomaterials, 2000 May, 21(9), 931 - 8
The degradation, swelling and erosion properties of biodegradable implants prepared by extrusion or compression moulding of poly(lactide-co-glycolide) and ABA triblock copolymers; Witt C et al.; In the design of parenteral delivery systems the modulation of the biodegradation of a polymer matrix represents a promising strategy to control drug release . We have investigated the degradation of ABA triblock copolymers, consisting of poly(lactide-co-glycolide) A-blocks and poly(oxyethylene) B-blocks, and PLG, poly(lactide-co-glycolide), with respect to swelling behaviour, molecular weight loss and polymer erosion . Implants were prepared by either compression moulding or extrusion using a laboratory ram extruder . Insertion of an elastoplastic B-block did not lower the processing temperature, but the entanglement of the polymer chains was significantly reduced as can be seen from the diameters of the extruded rods . The swelling of the rods showed a volume extension of 130% for an ABA containing 50% PEO and 20% for an ABA containing 20% PEO . Using 1H-NMR it was found that protons in the B-blocks of the swollen ABA copolymers were mobile, while the A-blocks remained rigid during incubation . The analysis of the pH inside ABA rods using electron paramagnetic resonance, EPR, gave a pH of 5.2 after incubation with a subsequent increase to pH 6.0 during the first day, approaching the pH of the medium after nearly 33 d . Acidic degradation products did not accumulate inside the ABA rods . Degradation and erosion started immediately upon incubation . By contrast, PLG rods showed the typical profile of degradation and erosion . In this case, the influence of the geometry of the device was insignificant . Consequently, ABA triblock copolymers may widen the spectrum of parenteral drug delivery with regard to release of pH-sensitive drugs as well as erosion-controlled release kinetics.

Biomaterials, 2000 May, 21(9), 889 - 98
Biodegradation behavior of ultra-high-strength hydroxyapatite/poly (L-lactide) composite rods for internal fixation of bone fractures; Furukawa T et al.; The purpose of this study was to investigate the biodegradation behavior of the ultra-high-strength hydroxyapatite/poly(L-lactide) (HA/PLLA) composite rods for fracture repair . Two kinds of composite materials were used in this study: u-HA/PLLA . which contained 30% by weight of uncalcined HA as reinforcing particles, and c-HA/PLLA, which contained 30% by weight of calcined HA as reinforcing particles . These composite rods were implanted in the subcutis and in the medullary cavities of rabbits . The specimens were removed at specific intervals between 2 and 52 weeks and the mechanical strength was measured for the rods in the subcutis, and the molecular weight and crystallinity were measured for the rods in both the subcutis and medullary cavities . The rod surfaces were examined using a scanning electron microscope (SEM) . The specimens were examined histologically by light microscopy . The bending strength of the composites implanted in the subcutis was maintained at more than 200 M Pa at 25 weeks and at 150 MPa at 52 weeks . The molecular weight dropped to 45% of the initial values at 8 weeks and to approximately 10% at 52 weeks . Significant differences in the molecular weight were seen between c-HA/PLLA and u-HA/PLLA, with u-HA/PLLA showing a faster rate of decrease than c-HA/PLLA after 8 weeks . SEM demonstrated that HA particles disappeared increasingly from the rod surfaces over time and that the spaces left by these HA particles formed many pores in the composite surfaces at 52 weeks . Histologically, a fibrous tissue layer was formed around the composite rod from 4 weeks in the subcutis and in the diaphyseal area of the medullary canal . This became more mature over time . Bony tissue contact to the composites without fibrous tissue layers was seen in the metaphyseal area of the medullary canal . During the experimental period, there were no inflammatory cells such as mono- or multi-nuclear phagocytes . Although further long-term studies for degradation are needed, the composites have promising mechanical strength and no adverse tissue reaction for use as fracture-fixation devices during the experimental periods.

Essays Biochem, 1999, 34, 31 - 49
Non-haem iron-containing oxygenases involved in the microbial biodegradation of aromatic hydrocarbons; Coulter ED et al.; A wide variety of aromatic hydrocarbons can be degraded aerobically by micro-organisms . A large fraction of the metabolic pathways are initiated by oxygenases containing Fe(II) at the active sites, which participates in the oxygenation and activation of the hydrocarbons . Mono-oxygenations and dioxygenations are found in these pathways . Some of these enzymes can catalyse either or both reactions, depending on the nature of the substrate . Two general themes are found: mononuclear Fe(II) centres that must be reduced by one electron at a time, or di-iron centres that can be reduced by two electrons . The electrons from NAD(P)H can be delivered by either an electron-transfer chain consisting of a flavin and one or more {2Fe-2S} centres, or a pterin . Proposed mechanisms generally involve higher oxidation states of the iron (Fe = O), analogous to those for P450, and peroxidase systems . These strong oxidants are necessary to oxidize aromatic and aliphatic compounds . Mechanisms currently considered viable for these reactions require significant changes in ligation during catalysis . The structures of the non-haem iron centres may be particularly well-suited for such transformations.

Lett Appl Microbiol, 2000 Jan, 30(1), 19 - 22
Selection of microbial populations degrading recalcitrant hydrocarbons of gasoline by monitoring of culture-headspace composition; Solano-Serena F et al.; A methodology was devised and was found useful for the selection of populations degrading recalcitrant hydrocarbons . The work was part of a programme aiming at developing knowledge of the intrinsic capacities of autochtonous microflorae of the environment for gasoline biodegradation . The methodology involved monitoring the progress of degradation in enrichment liquid cultures on the selected hydrocarbon by gas chromatographic analysis of CO2 production and O2 consumption . Populations degrading in particular o-xylene, 1,2,4-trimethylbenzene, cyclohexane were obtained . Concerning 2,2,4-trimethylpentane (isooctane), one microflora (and a pure strain derived from it) growing on this hydrocarbon were obtained from gasoline-polluted water.

Eur J Biochem, 2000 Apr, 267(7), 2122 - 6
Intracellular trafficking and release of intact edible mushroom lectin from HT29 human colon cancer cells; Yu LG et al.; Our previous studies have shown that the Galbeta1-3GalNAcalpha- (Thomsen-Friedenreich antigen)-binding lectin from the common edible mushroom Agaricus bisporus (ABL) reversibly inhibits cell proliferation, and this effect is a consequence of inhibition of nuclear localization sequence-dependent nuclear protein import after ABL internalization {Yu, L.G., Fernig, D.G., White, M.R.H., Spiller, D.G., Appleton, P., Evans, R.C., Grierson, I., Smith, J.A., Davies, H., Gerasimenko, O.V., Petersen, O.H., Milton, J.D . & Rhodes, J.M . (1999) J . Biol . Chem . 274, 4890-4899} . Here, we have investigated further the intracellular trafficking and fate of ABL after internalization in HT29 human colon cancer cells . Internalization of 125I-ABL occurred within 30 min of the lectin being bound to the cell surface . Subcellular fractionation after pulse labelling of the cells with 125I-ABL for 2 h at 4 degrees C followed by culture of the cells at 37 degrees C demonstrated a steady increase in radioactivity in a crude nuclear extract . The radioactivity in this extract reached a maximum after 10 h and declined after 20 h . Release of ABL from the cell, after pulse labelling, was assessed using both fluorescein isothiocyanate-labelled ABL and 125I-ABL and was slow, with a t1/2 of 48 h . Most of the 125I-ABL both inside cells and in the medium remained intact, as determined by trichloroacetic acid precipitation and SDS/PAGE, and after 48 h only 22 +/- 2% of ABL in the medium and 14 +/- 2% inside the cells was degraded . This study suggests that the reversibility of the antiproliferative effect of ABL is associated with its release from cells after internalization . The internalization and subsequent slow release, with little degradation of ABL, reflects the tendency of lectins to resist biodegradation and implies that other endogenous or exogenous lectins may be processed in this way by intestinal epithelial cells.

Appl Microbiol Biotechnol, 2000 Feb, 53(2), 243 - 8
Role of the reactor configuration in the biological detoxification of a dump site-polychlorobiphenyl-contaminated soil in lab-scale slurry phase conditions; Fava F et al.; The biotreatability of a xenobiotic contaminated soil is frequently determined through a bioslurry treatment usually performed in lab-scale shaken baffled flasks . In this study, a 3-1 unconventional stirred tank reactor was developed and tested in the slurry-phase treatment of a soil heavily contaminated by polychlorobiphenyls (PCBs) derived from an Italian dump site, in the absence and in the presence of biphenyl and of the exogenous PCB aerobically dechlorinating co-culture ECO3 . The data obtained were compared with those obtained on the same soil in experiments performed in parallel in 3-1 baffled shaken flask reactors . Considerably higher PCB removal and soil detoxification yields (determined through the Lepidium sativum germination test and the Collembola mortality test) were attained in the stirred tank reactors, which generally displayed a higher slurry-phase homogeneity and a higher availability of biphenyl- and chlorobenzoic acid-degrading bacteria compared to the corresponding shaken flask reactors . Moreover, enhanced soil PCB biodegradation and detoxification yields were observed when the developed reactor was supplemented with biphenyl and the exogenous ECO3 bacteria . In conclusion, the results of the soil biotreatability experiments commonly performed in bioslurry lab-scale reactors are significantly influenced by the reactor configuration; the use of the unconventional stirred tank reactor system developed in this work is recommended.

J Hazard Mater, 2000 Apr 3, 73(2), 179 - 97
Attenuation mechanisms of N-nitrosodimethylamine at an operating intercept and treat groundwater remediation system; Gunnison D et al.; The North Boundary Containment System (NBCS), an intercept-and-treat system, was established at Rocky Mountain Arsenal (RMA), Commerce City, CO, to remove low-level organic contaminants from a groundwater plume exiting RMA to the north and northwest . N-nitrosodimethylamine (NDMA) was detected in groundwater collected from the dewatering and recharge zones of the NBCS system . Concern over the fate of NDMA, in terms of potentially exiting the boundaries of the arsenal, prompted an investigation to evaluate potential attenuation mechanisms for NDMA within the alluvial aquifer system and within the NBCS itself . Groundwater, soil, and granular activated carbon (GAC) samples were taken from key locations in the NBCS system . Soil and GAC samples were assayed for sorption kinetics and for adsorption and desorption properties using 14C-labeled NDMA . NDMA biodegradation experiments were conducted by following 14CO(2) evolution from 14C-labeled NDMA in soils and GAC samples under aerobic and anaerobic conditions . The sorptive capacity of the site soils for NDMA was insignificant . Furthermore, the adsorption of the NDMA by the soil was almost completely reversible . Evaluation of the degradation potential of the native microbial consortia indicated a high level of NDMA mineralization when measured using bench-scale microcosms . The native consortia had capability to mineralize the NDMA under both aerobic and anaerobic incubations, indicating facultative characteristics . Testing of the local groundwater chemistry revealed that the area of the aquifer of interest was microaerobic and neutral in pH . These conditions were optimal for NDMA removal . While sorption was insignificant, degradation was a significant attenuation mechanism, which may be the reason that no NDMA has migrated off-site . This gives rise to the potential of a long-term sink for attenuating NDMA within the recharge zone of the treatment system.

Trends Microbiol, 2000 Mar, 8(3), 128 - 33
Horizontal gene transfer and the origin of species: lessons from bacteria; de la Cruz F et al.; In bacteria, horizontal gene transfer (HGT) is widely recognized as the mechanism responsible for the widespread distribution of antibiotic resistance genes, gene clusters encoding biodegradative pathways and pathogenicity determinants . We propose that HGT is also responsible for speciation and sub-speciation in bacteria, and that HGT mechanisms exist in eukaryotes.

Ecotoxicol Environ Saf, 2000 Mar, 45(3), 274 - 83
Shake-flask test for determination of biodegradation rates of (14)C-labeled chemicals at low concentrations in surface water systems; Ingerslev F et al.; A simple shake-flask surface water biodegradability die away test with (14)C-labeled chemicals added to microgram per liter concentrations (usually 1-100 microg/L) is described and evaluated . The aim was to provide information on biodegradation behavior and kinetic rates at environmental (low) concentrations in surface water systems . The basic principle of measurement was to determine evolved CO(2) indirectly from measurements of total organic activity in subsamples after stripping off their content of CO(2) . Used with surface water alone the test simulates a pelagic environment and amended with sediments (0.1-1 dry weight/L) the test is intended to simulate a water environment with suspended solids (e.g., resuspended sediments) . A protocol of the test used with the (14)C technique or with specific chemical analysis was recently developed by the International Organization for Standardization . Practical experience with the method is presented for a set of reference substances . These substances could be ranked in five groups of decreasing biodegradability: aniline>p-nitrophenol, 2, 4-dichlorophenoxyacetic acid>4-chloroaniline>maleic hydrazide, pentachlorophenol>atrazine . It was found that degradation rates and lag periods varied considerably among sampling sites and sometimes also among samples from the same site . No significant correlation could be established between degradation rates and microbial biomass estimates . Even small portions of added sediments greatly enhanced biodegradation of the absorbable compound pentachlorophenol, probably by providing sites for microbial attachment . Repeated tests indicated consistent degradation behavior for the readily degradable substances, whereas degradation sometimes stopped or failed with the more recalcitrant substances . A preadaptation step involving regular reinoculation with freshly collected surface water could, however, overcome the problems of false-negative results .

Appl Environ Microbiol, 2000 Mar, 66(3), 1007 - 19
Degradation and mineralization of high-molecular-weight polycyclic aromatic hydrocarbons by defined fungal-bacterial cocultures; Boonchan S et al.; This study investigated the biodegradation of high-molecular-weight polycyclic aromatic hydrocarbons (PAHs) in liquid media and soil by bacteria (Stenotrophomonas maltophilia VUN 10,010 and bacterial consortium VUN 10,009) and a fungus (Penicillium janthinellum VUO 10, 201) that were isolated from separate creosote- and manufactured-gas plant-contaminated soils . The bacteria could use pyrene as their sole carbon and energy source in a basal salts medium (BSM) and mineralized significant amounts of benzo{a}pyrene cometabolically when pyrene was also present in BSM . P . janthinellum VUO 10,201 could not utilize any high-molecular-weight PAH as sole carbon and energy source but could partially degrade these if cultured in a nutrient broth . Although small amounts of chrysene, benz{a}anthracene, benzo{a}pyrene, and dibenz{a,h}anthracene were degraded by axenic cultures of these isolates in BSM containing a single PAH, such conditions did not support significant microbial growth or PAH mineralization . However, significant degradation of, and microbial growth on, pyrene, chrysene, benz{a}anthracene, benzo{a}pyrene, and dibenz{a,h}anthracene, each as a single PAH in BSM, occurred when P . janthinellum VUO 10,201 and either bacterial consortium VUN 10,009 or S . maltophilia VUN 10,010 were combined in the one culture, i.e., fungal-bacterial cocultures: 25% of the benzo{a}pyrene was mineralized to CO(2) by these cocultures over 49 days, accompanied by transient accumulation and disappearance of intermediates detected by high-pressure liquid chromatography . Inoculation of fungal-bacterial cocultures into PAH-contaminated soil resulted in significantly improved degradation of high-molecular-weight PAHs, benzo{a}pyrene mineralization (53% of added {(14)C}benzo{a}pyrene was recovered as (14)CO(2) in 100 days), and reduction in the mutagenicity of organic soil extracts, compared with the indigenous microbes and soil amended with only axenic inocula.

Can J Microbiol, 2000 Jan, 46(1), 38 - 49
Hydrocarbon-degrading filamentous fungi isolated from flare pit soils in northern and western Canada; April TM et al.; Sixty-four species of filamentous fungi from five flare pits in northern and western Canada were tested for their ability to degrade crude oil using gas chromatographic analysis of residual hydrocarbons following incubation . Nine isolates were tested further using radiorespirometry to determine the extent of mineralization of model radiolabelled aliphatic and aromatic hydrocarbons dissolved in crude oil . Hydrocarbon biodegradation capability was observed in species representing six orders of the Ascomycota . Gas chromatography indicated that species capable of hydrocarbon degradation attacked compounds within the aliphatic fraction of crude oil, n-C12-n-C26; degradation of compounds within the aromatic fraction was not observed . Radiorespirometry, using n-{1-14C}hexadecane and {9-14C}phenanthrene, confirmed the gas chromatographic results and verified that aliphatic compounds were being mineralized, not simply transformed to intermediate metabolites . This study shows that filamentous fungi may play an integral role in the in situ biodegradation of aliphatic pollutants in flare pit soils.

Biochem Biophys Res Commun, 2000 Mar 5, 269(1), 117 - 23
Chemotaxis of a Ralstonia sp . SJ98 toward different nitroaromatic compounds and their degradation; Samanta SK et al.; A Ralstonia sp . SJ98, isolated by a chemotactic enrichment technique, was capable of utilizing different nitroaromatic compounds (NACs) . It utilized p-nitrophenol, 4-nitrocatechol, o-nitrobenzoic acid, and p-nitrobenzoic acid as the sole source of carbon and energy . It was observed that Ralstonia sp . SJ98 was chemotactic to the above-mentioned NACs as tested by the drop assay, swarm plate assay, and capillary assay . However, it failed to show chemotactic behavior toward those compounds which were not degraded by the microorganism . This is the first report which shows the chemotaxis of a microorganism toward different NACs and their subsequent degradation . Some of the intermediates of the NACs' degradative pathways have been identified using TLC, GC, and GC-MS studies . The results presented here indicate a correlation between chemotaxis and biodegradation of NACs .

An R Acad Nac Med (Madr), 1999, 116(2), 297 - 323; discussion 323-5
{Arterial grafts}; Tamames Escobar S; After a historical review, pointing out the different types of grafts (tubes, veins, arteries, synthetic material), several haemodynamics facts are commented, that in author's opinion, are closely related with biological process of "neo-intima" development . Technical aspects are evaluated, including extra-anatomical by-pass, infection risk, and proposed solutions when run-off problems occurred when placing a graft, concluding with modern guidances when using this material, such as endotheliation, cryopreserved artery grafts, polyurethane and pyrolytic carbon grafts, negatively charged grafts, biodegradation prosthesis, laboratory artery development, small diameter grafts and endovascular surgery.

Artif Cells Blood Substit Immobil Biotechnol, 2000 Jan, 28(1), 79 - 94
The anticalcification effect of polyethylene glycol-immobilized on hexamethylene diisocyanate treated pericardium; Vasudev SC et al.; Pathologic calcification is thought to be the main cause of failure in the present generation tissue valves fabricated from glutaraldehyde pretreated bovine pericardium (BP) . The present investigation describes the in vitro calcification and enzymatic degradation of bovine pericardia after hexamethylene diisocyanate (HMDIC) crosslinking and subsequent modification with polyethylene glycol . The enzymatic degradation of these treated surfaces were monitored by scanning electron micrography and tensile strength measurements . Various proteases, such as alpha-chymotrypsin, bromelain, esterase, trypsin and collagenase were investigated for tissue stability . Incubation of these enzymes with crosslinked pericardia had variably reduced their tensile strength . Among these treated surfaces, polyethylene glycol (PEG) grafted BP via isocyanate functionalities had retained maximum strength . The PEG modified tissues had also indicated a substantial reduction in calcification, when compared to other treated tissues . Further, the biocompatibility of various pericardial tissues were established by platelet adhesion and octane contact angle measurements . It is assumed that the PEG modification of pericardium may interfere with the cellular activation of injury (platelets) to reduce tissue associated calcification . In conclusion, it seems the PEG modification of bovine pericardium via HMDIC may provide new ways of controlling tissue biodegradation and calcification . However, more in vivo studies are needed to develop applications.

Chemosphere, 2000 Jan, 40(1), 99 - 102
An analysis of the 'Modified Sturm Test' data; Srinivasan PT et al.; The 'Modified Sturm Test' uses carbon dioxide production as the primary end point in assessing the biodegradation potential of organic chemicals . This test was conducted by a commercial laboratory to assess the potential biodegradability of an oil stabilizer sample from an oil company in Canada . There was a high percentage conversion of total organic carbon present in the sample but carbon dioxide measured was low . Many possibilities were analyzed in this paper in order to understand the situation . The analysis showed that the test was subject to criticism from the point of view of CO2 measurement, 10-day window period, and aeration/mixing conditions.

Chemosphere, 2000 Feb, 40(4), 359 - 67
Effects of heterocyclic PAHs (N, S, O) on the biodegradation of typical tar oil PAHs in a soil/compost mixture; Meyer S et al.; The interaction phenomena during the biodegradation of typical coal tar polycyclic aromatic hydrocarbons and their heterocyclic analogues (N, S, O) were investigated in an artificially contaminated AhA1-horizon/compost mixture . All compounds were partly or completely biodegraded . Degradation of two- to five-ring PAHs was inhibited by the presence of hetero-PAHs, whereas degradation of just some hetero-PAHs was inhibited by the presence of PAHs . Among the hetero-PAHs the sulphur-containing compounds were less susceptible to degradation than the corresponding oxygen- or nitrogen-containing analogues . The basic azaarene acridine showed an extreme persistence and strong sorption to the soil matrix proved by an increase of recovery after saponification of the soil matrix.

Chemosphere, 2000 Mar, 40(5), 557 - 63
Biodegradation of pyrene by sediment fungi; Ravelet C et al.; Micromycetes were isolated from PAHS-contaminated sediment and identified . They were investigated for pyrene degradation (10 mg l-1) in liquid synthetic medium for two days . Among the 41 strains isolated, 10 highly degraded pyrene (> 2.4 mg g-1 dry weight): two Zygomycetes (Mucor racemosus, M . racemosus var . sphaerosporus), 6 Deuteromycetes (Gliocladium virens, Penicillium simplicissimum, P . janthinellum, Phialophora alba, P . hoffmannii, Trichoderma harzianum), a Dematiaceae (Scopulariopsis brumptii) and a Sphaeropsidale (Coniothyrium fuckelii) . Zygomycetes appeared as one of the most efficient taxonomic groups, especially with Mucor racemosus . Penicillium crustosum was the only strain that did not degrade pyrene . Among the 10 fungi which were performant for pyrene degradation, nine were not yet reported in the literature and showed a real value for PAH remediation.

Folia Microbiol (Praha), 1999, 44(3), 323 - 7
Primary biodegradation of a series of alkyl sulfosuccinates by mixed bacterial culture; Gregorova D et al.; A mixed bacterial culture capable of primary biodegradation of sodium alkyl sulfosuccinates R1-OOC-CH(SO3Na)-CH2-COO-R2 was obtained from soil microorganisms by enrichment cultivation and adaptation in the presence of mono-n-dodecyl sulfosuccinate . Gram-negative psychrophilic bacteria with proteolytic, lipolytic and ammonifying activities were prevalent in the culture . The process of primary biodegradation of alkyl sulfosuccinates can be described by first-order reaction kinetics . The rate constants for linear esters were ascending in the order C4 < C5 < C6 (45 mumol/min per g cell protein) and further descending with increasing length of the carbon chain C6 > C8 >> C13 . Substitution of cyclohexyl for n-hexyl group resulted in fourfold decrease in biodegradation rate . Terminal branching of alkyl chain does not affect the rate of primary biodegradation.

Ophthalmic Res, 2000 Jan-Feb, 32(1), 19 - 24
Experimental corneal neovascularization by basic fibroblast growth factor incorporated into gelatin hydrogel; Yang CF et al.; The study was designed to investigate the feasibility of using an acidic gelatin hydrogel as a biodegradable vehicle for basic fibroblast growth factor (bFGF) . bFGF was incorporated by polyion complexation into a biodegradable hydrogel prepared by cross-linking acidic gelatin with the isoelectric point of 4.9 . The dried hydrogel (sized to 2x1 mm) was hydrated with bFGF aqueous solution including different doses of bFGF (20, 50, 125, 250 and 500 ng) and implanted into a rabbit corneal pocket (2.5x2 mm) . As a control group, the gelatin hydrogel without bFGF or bFGF alone (500 ng) was used . Corneal angiogenesis was evaluated by biomicroscopy, corneal fluorescein angiography and histology for 21 days . Photographs were taken and corneal angiogenesis was evaluated by image analysis . The hydrogel degraded with time after its implantation into the corneal pocket . Experimental eyes receiving the hydrogel containing more than 50 ng of bFGF demonstrated significant corneal angiogenesis . Control eyes and eyes receiving the hydrogel containing 20 ng of bFGF showed no corneal angiogenesis . Corneal angiogenesis, which occurred on the 3rd or 4th day after implantation, reached maximal growth on about day 7 and regressed from day 10 after implantation . The area of angiogenesis showed a dose-dependency on bFGF . The gelatin hydrogel itself induced neither angiogenesis nor inflammation . These results suggested that acidic gelatin hydrogel releases bioactive bFGF with its biodegradation, resulting in corneal neovascularization .

J Biomater Appl, 2000 Jan, 14(3), 273 - 95
Effects of double cross-linking technique on the enzymatic degradation and calcification of bovine pericardia; Vasudev SC et al.; The strength, resorption rates, and biocompatibility of collagenous biomaterials are profoundly influenced by the method of cross-linking . The in vitro and in vivo calcification and enzymatic degradation of bovine pericardia (BP) after a series of surface modifications were studied as a function of exposure time . Collagenase degradations of modified BP were monitored by scanning electron microscopy and tensile strength measurements . Bovine pericardium was modified by a combination of different tissue fixatives such as glutaraldehyde (GA), carbodiimide (EDC), diisocyanate (HMDIC), and polyethylene glycol (PEG) . GA-PEG-EDC-PEG and GA-PEG-HMDIC-PEG combination treated BP retained maximum stability in collagenase digestion compared to GATBP . In vitro calcification studies and in vivo rat subcutaneous implantations of modified pericardium have shown substantial reduction in the calcification of double cross-linked BP with PEG modification . Further, the biocompatibility aspects of pericardial tissues were established by platelet adhesion and octane contact angle . It seems that cross-links involving amino and carboxyl residues may provide new ways of controlling biodegradation and calcification.

Appl Environ Microbiol, 2000 Feb, 66(2), 481 - 6
Characterization of 4-hydroxyphenylacetate 3-hydroxylase (HpaB) of Escherichia coli as a reduced flavin adenine dinucleotide-utilizing monooxygenase; Xun L et al.; 4-Hydroxyphenylacetate 3-hydroxylase (HpaB and HpaC) of Escherichia coli W has been reported as a two-component flavin adenine dinucleotide (FAD)-dependent monooxygenase that attacks a broad spectrum of phenolic compounds . However, the function of each component in catalysis is unclear . The large component (HpaB) was demonstrated here to be a reduced FAD (FADH(2))-utilizing monooxygenase . When an E . coli flavin reductase (Fre) having no apparent homology with HpaC was used to generate FADH(2) in vitro, HpaB was able to use FADH(2) and O(2) for the oxidation of 4-hydroxyphenylacetate . HpaB also used chemically produced FADH(2) for 4-hydroxyphenylacetate oxidation, further demonstrating that HpaB is an FADH(2)-utilizing monooxygenase . FADH(2) generated by Fre was rapidly oxidized by O(2) to form H(2)O(2) in the absence of HpaB . When HpaB was included in the reaction mixture without 4-hydroxyphenylacetate, HpaB bound FADH(2) and transitorily protected it from rapid autoxidation by O(2) . When 4-hydroxyphenylacetate was also present, HpaB effectively competed with O(2) for FADH(2) utilization, leading to 4-hydroxyphenylacetate oxidation . With sufficient amounts of HpaB in the reaction mixture, FADH(2) produced by Fre was mainly used by HpaB for the oxidation of 4-hydroxyphenylacetate . At low HpaB concentrations, most FADH(2) was autoxidized by O(2), causing uncoupling . However, the coupling of the two enzymes' activities was increased by lowering FAD concentrations in the reaction mixture . A database search revealed that HpaB had sequence similarities to several proteins and gene products involved in biosynthesis and biodegradation in both bacteria and archaea . This is the first report of an FADH(2)-utilizing monooxygenase that uses FADH(2) as a substrate rather than as a cofactor.

J Hazard Mater, 2000 Feb 25, 72(2-3), 217 - 36
Field and numerical analysis of in-situ air sparging: a case study; Benner ML et al.; An in-situ air sparging operation was used to remediate the sandy subsurface soils and shallow groundwater under a drum storage site near Chicago, IL, where either periodic or random spillage of a light non-aqueous phase liquid (LNAPL) occurred between 1980 and 1987 . Both field measurements and model simulations using commercially available computer software suggested that microbial degradation was the most significant contributor to the removal of contaminant mass . Toluene, ethylbenzene and total xylenes (TEX), which were of major concern with regards to reaching clean-up criteria at the site, were observed to decline by 88% in concentration . Furthermore, up to 97% of the total mass removed through microbial degradation consisted of TEX . Of the total contaminant spill, up to 23% of initial organic chemical mass was removed through microbial degradation compared to less than 6% by physical stripping . Greater loss to microbial degradation is most likely attributed to the relatively low air injection rate used during the course of the air sparging remediation . Evaluation of air sparging at the site using model simulations supported this analysis by estimating 140 and 620 kg of total contaminant mass being removed through volatilization and biodegradation, respectively . An evaluation of several system design parameters using model simulations suggested that only the type of sparging operation (i.e . pulsed or continuous) was significant in terms of total contaminant removal time, while both the sparging operation and air injection rate were significant in terms of removal of a critical species, total xylenes.

J Hazard Mater, 2000 Feb 25, 72(2-3), 101 - 19
Performance of air sparging systems: a review of case studies; Bass DH et al.; Fluor Daniel GTI (now IT Corporation) has compiled a database of 49 completed in-situ air sparging case studies . Air sparging is a commonly used remediation technology which volatilizes and enhances aerobic biodegradation of contamination in groundwater and saturated zone soil . The air sparging database was compiled to address questions regarding the effectiveness and permanence of air sparging, and to provide predictive indicators of air sparging success to aid in optimization of existing and future air sparging systems . In each case study, groundwater concentrations were compared before sparging was initiated, just before sparging was terminated, and in the months following shutdown of the sparging system . The case studies included both chlorinated solvents and petroleum hydrocarbon contamination, and covered a wide range of soil conditions and sparge system parameters . In many cases, air sparging achieved a substantial and permanent decrease in groundwater concentrations . Successful systems were achieved with both chlorinated and petroleum contamination, both sandy and silty soils, and both continuous and pulsed flow sparging . In other cases, however, a significant rebound of groundwater concentrations was observed after sparging was terminated . Rebound sometimes required 6 to 12 months to develop fully . Rebound was more frequently observed at sites contaminated with petroleum hydrocarbons than with chlorinated solvents . Petroleum-contaminated sites were more likely to rebound when initial groundwater contamination levels were high enough to suggest the presence of LNAPL or a smear zone of residual LNAPL . Rebound at petroleum sites appeared to be minimized by a high density of sparge wells addressing the entire source area and a high sparge air injection rate . In some cases, rebound appeared to be related to a rising water table.

Pharm Res, 1999 Dec, 16(12), 1825 - 9
Sustained release of human growth hormone from PLGA solution depots; Brodbeck KJ et al.; PURPOSE: The effects of altering the dynamics of phase inversion of a polylactic glycolic acid (PLGA) solution depot on the sustained-release delivery profile of human growth hormone (hGH) were evaluated . The impact of adjusting the protein particle composition was also studied in a slow phase-inverting formulation . METHODS: Protein release profiles of depots prepared from four model solvents were generated by injecting formulations into the subcutaneous space of normal rats and monitoring hGH serum levels over the course of 1 month . Scanning electron microscopy, Coulometric Karl Fischer titration, size-exclusion liquid chromatography, and reversed-phase liquid chromatography were used to observe depot morphologies, bulk water absorption, PLGA degradation, and protein particle dissolution rates, respectively . RESULTS: An extended-release profile and significantly reduced burst effect resulted when the aqueous affinity of the depot solvent was reduced . As seen earlier in in vitro experiments, lowering the solvent's aqueous affinity slows the phase inversion rate, which in turn produces depot morphologies favorable to prolonged release . Protein burst on injection was entirely eliminated in a slow phase-inverting formulation by densifying the lyophilized protein particles . Unlike the use of metal cations to prolong release of some proteins in PLGA microsphere depots, this technique is more universal, and thus is potentially usable with any protein or highly soluble drug agent . The onset of biodegradation was observed to occur at 14 days for all depot formulations, however the bulk biodegradation rate slowed as the aqueous affinity of the depot solvent decreased . This result supports the hypothesis that, in a slow phase-inverting system, drug release over the first few weeks is governed by the diffusion rate of drug through the polymer solution . CONCLUSIONS: By taking advantage of the effects of low aqueous affinity and protein particle densification, a PLGA solution depot was produced with the capability of sustaining hGH levels in normal rats at a serum level of 10 to 200 ng/ml for 28 days.

J Control Release, 2000 Feb 14, 64(1-3), 133 - 42
Bone regeneration by transforming growth factor beta1 released from a biodegradable hydrogel; Yamamoto M et al.; This paper describes the sustained release of transforming growth factor beta1 (TGF-beta1) from a biodegradable hydrogel based on polyion complexation for the enhancement of bone regeneration activity . Basic TGF-beta1 was adsorbed onto the biodegradable hydrogel of acidic gelatin with an isoelectric point of 5.0 by an electrostatic interaction . The TGF-beta1 could not be adsorbed onto basic gelatin . When acidic gelatin hydrogels incorporating 125I-labeled TGF-beta1 were implanted into the back subcutis of mice, the radioactivity decreased with time and the in vivo retention of TGF-beta1 was prolonged with a decrease in the water content of hydrogels . The higher the water content of hydrogels, the faster their biodegradation . The in vivo retention of TGF-beta1 correlated well with that of gelatin hydrogels, indicating that TGF-beta1 was released from the gelatin hydrogel as a result of hydrogel biodegradation . The ability of TGF-beta1-incorporated into acidic gelatin hydrogels to induce bone regeneration was evaluated in a rabbit calvarial defect model . Eight weeks after treatment, the gelatin hydrogels with water contents of 90 and 95 wt% induced significantly high bone regeneration compared with those with lower and higher water contents and free TGF-beta1 . This indicates that the sustained release of TGF-beta1 from the hydrogel with suitable in vivo degradability is necessary to effectively enhance its osteoinductive function . Rapid hydrogel degradation will result in a retention time of TGF-beta1 which is too short to induce bone regeneration . It is possible that the slow degradation of the hydrogel physically blocked TGF-beta1-induced bone regeneration at the skull defect . It can be concluded that the gelatin hydrogel is a promising matrix of TGF-beta1 release to induce skull bone regeneration.

J Bacteriol, 2000 Feb, 182(3), 789 - 95
Identification of an extradiol dioxygenase involved in tetralin biodegradation: gene sequence analysis and purification and characterization of the gene product; Andujar E et al.; A genomic region involved in tetralin biodegradation was recently identified in Sphingomonas strain TFA . We have cloned and sequenced from this region a gene designated thnC, which codes for an extradiol dioxygenase required for tetralin utilization . Comparison to similar sequences allowed us to define a subfamily of 1, 2-dihydroxynaphthalene extradiol dioxygenases, which comprises two clearly different groups, and to show that ThnC clusters within group 2 of this subfamily . 1,2-Dihydroxy-5,6,7, 8-tetrahydronaphthalene was found to be the metabolite accumulated by a thnC insertion mutant . The ring cleavage product of this metabolite exhibited behavior typical of a hydroxymuconic semialdehyde toward pH-dependent changes and derivatization with ammonium to give a quinoline derivative . The gene product has been purified, and its biochemical properties have been studied . The enzyme is a decamer which requires Fe(II) for activity and shows high activity toward its substrate (V(max), 40.5 U mg(-1); K(m), 18 . 6 microM) . The enzyme shows even higher activity with 1, 2-dihydroxynaphthalene and also significant activity toward 1, 2-dihydroxybiphenyl or methylated catechols . The broad substrate specificity of ThnC is consistent with that exhibited by other extradiol dioxygenases of the same group within the subfamily of 1, 2-dihydroxynaphthalene dioxygenases.

Nucleic Acids Res, 2001 Jan 1, 29(1), 340 - 3
The University of Minnesota Biocatalysis/Biodegradation Database: emphasizing enzymes; Ellis LB et al.; The University of Minnesota Biocatalysis/Biodegradation Database (UM-BBD, provides curated information on microbial catabolic enzymes and their organization into metabolic pathways . Currently, it contains information on over 400 enzymes . In the last year the enzyme page was enhanced to contain more internal and external links; it also displays the different metabolic pathways in which each enzyme participates . In collaboration with the Nomenclature Commission of the International Union of Biochemistry and Molecular Biology, 35 UM-BBD enzymes were assigned complete EC codes during 2000 . Bacterial oxygenases are heavily represented in the UM-BBD; they are known to have broad substrate specificity . A compilation of known reactions of naphthalene and toluene dioxygenases were recently added to the UM-BBD; 73 and 108 were listed respectively . In 2000 the UM-BBD is mirrored by two prestigious groups: the European Bioinformatics Institute and KEGG (the Kyoto Encyclopedia of Genes and Genomes) . Collaborations with other groups are being developed . The increased emphasis on UM-BBD enzymes is important for predicting novel metabolic pathways that might exist in nature or could be engineered . It also is important for current efforts in microbial genome annotation.

Anal Chem, 2000 Nov 15, 72(22), 5669 - 72
Carbon isotope effects resulting from equilibrium sorption of dissolved VOCs; Slater GF et al.; To accurately interpret isotopic data obtained for volatile organic compounds (VOCs) dissolved in groundwater systems, the isotopic effects of subsurface processes must be understood . Previous work has demonstrated that volatilization and dissolution of BTEX and chlorinated ethene compounds are not significantly isotopically fractionating . This study characterized the carbon isotopic effects of equilibrium sorption of perchloroethylene, trichloroethylene, benzene, and toluene to both graphite and activated carbon directly in batch experiments over a range of 10-90% sorption . Results demonstrate that, over this range, equilibrium sorption of these VOCs to graphite and activated carbon does not result in significant carbon isotopic fractionation within the +/-0.5% accuracy and reproducibility associated with compound-specific isotope analysis . This implies that the isotopic values of dissolved VOCs will not be significantly affected by equilibrium sorption in the subsurface . Therefore, isotopic analysis has potential to be used in the field to differentiate between mass losses due to isotopically fractionating processes such as biodegradation versus mass loss due to nondegradative processes.

J Drug Target, 1999, 7(1), 11 - 32
Genetically engineered polymers for drug delivery; Nagarsekar A et al.; Genetic engineering methodology offers the ability to synthesize protein-based polymers with precisely controlled structures . Protein-based polymers synthesized by recombinant techniques have a well-defined monomer composition and sequence, stereochemistry, and a narrow molecular weight distribution . The structure of the polymeric carrier at the molecular level influences its biological disposition and drug release profile . Current methodologies of polymer synthesis (chemical polymerization) result in the production of polymers with heterogeneous molecular weights, and with monomer sequences and compositions defined in terms of statistical distributions . Genetic engineering methodologies can be used to design new polymeric drug carriers with improved properties, such as better-defined biorecognition, pharmacokinetic, biodegradation, and drug release profiles . In this review article the rationale and methodology of polymer synthesis using genetic engineering techniques, the status of such polymers in drug delivery to-date, and the potential of these polymers for the development of new systems in the future are discussed.

Int J Oral Maxillofac Implants, 1999 Nov-Dec, 14(6), 835 - 40
Bone reactions to anorganic bovine bone (Bio-Oss) used in sinus augmentation procedures: a histologic long-term report of 20 cases in humans; Piattelli M et al.; Many materials are used for sinus augmentation procedures . Anorganic bovine bone (Bio-Oss) has been reported to be osteoconductive, and no inflammatory responses have been observed with the use of this biomaterial . One of the main questions pertaining to Bio-Oss concerns its biodegradation and substitution by host bone . Some investigators have observed rapid replacement by host bone, while other researchers observed slow resorptive activity or no resorption at all . The aim of the present study was to conduct a long-term histologic analysis of retrieved specimens in humans where Bio-Oss was used in sinus augmentation procedures . Specimens were retrieved from 20 patients after varying periods from 6 months to 4 years and were processed to obtain thin ground sections . Bio-Oss particles were surrounded for the most part by mature, compact bone . In some Haversian canals it was possible to observe small capillaries, mesenchymal cells, and osteoblasts in conjunction with new bone . No gaps were present at the interface between the Bio-Oss particles and newly formed bone . In specimens retrieved after 18 months and 4 years, it was also possible to observe the presence of osteoclasts in the process of resorbing the Bio-Oss particles and neighboring newly formed bone . Bio-Oss appears to be highly biocompatible and osteoconductive, is slowly resorbed in humans, and can be used with success as a bone substitute in maxillary sinus augmentation procedures.

J Biomater Sci Polym Ed, 1999, 10(11), 1171 - 81
Cross-linking of amniotic membranes; Fujisato T et al.; Human amniotic membrane was cross-linked with chemical and radiation methods to investigate the effect of cross-linking on its physicochemical and biodegradation properties . Radiation cross-linking was performed with gamma-ray and electron beam while chemical cross-linking was with glutaraldehyde (GA) . Both gamma-ray and electron beam irradiation decreased the tensile strength and elongation at break of the amniotic membrane with an increase in the irradiation dose, whereas GA cross-linking had no effect on the tensile properties . This is probably due to the scission of collagen chains through irradiation . No significant change was observed on the water content of cross-linked amniotic membranes for any of the crosslinking methods and in marked contrast with cross-linking of a gelatin membrane . A permeation study revealed that protein permeation through the amniotic membrane was not influenced by the GA concentration at cross-linking . These findings are ascribed to the structure characteristic of the amniotic membrane . The membrane is composed of a fibrous mesh structure from an assemblage of collagen fibers . It is possible that cross-linking takes place in the interior of the fiber assembly without impairing the mesh structure, resulting in no change of the water content and protein permeability . In vitro degradation of cross-linked amniotic membranes revealed that radiation cross-linking appeared to be much less effective than GA cross-linking in retarding the degradation, probably because of low cross-linking densities . GA-cross-linked amniotic membranes were degraded more slowly as the GA concentration at cross-linking increased . When the GA-cross-linked amniotic membrane was subcutaneously implanted in the rat, the tissue response was mild, similar to that of the non-cross-linked native membrane.

J Biomater Sci Polym Ed, 1999, 10(11), 1159 - 70
Polyurethanes based on dihydroxamic acids . Synthesis, chemical characterization, and biological activity; Buruiana T et al.; A series of segmented polyurethanes based on polyethylene oxide/polycaprolactone diol, isophorone diisocyanate, and dihydroxamic acids were synthesized and characterized . Biocompatibility and antitumoral activity were in vivo tested on Wistar male rats and Wistar rats affected with Walker 256 carcinosarcoma, respectively . The effect of dihydroxamic acid structure on the biological properties was determined . A better antitumoral response of the polyurethanes containing aliphatic dihydroxamic segment compared with those which resulted using terephthaloyl dihydroxamic acid was evidenced . With increasing polymer chain polyethylene oxide content the antitumoral activity was also enhanced . Some attempts on the in vitro biodegradation of above polyurethanes were also performed.

Biochem Biophys Res Commun, 1999 Dec 20, 266(2), 322 - 5
Characterization of 2,6-dichloro-p-hydroquinone 1,2-dioxygenase (PcpA) of Sphingomonas chlorophenolica ATCC 39723; Xun L et al.; Pentachlorophenol (PCP) is a general biocide and a major environmental pollutant . The initial steps of PCP degradation by Sphingomonas chlorophenolica ATCC 39723 have been studied and characterized . Two enzymes are responsible for converting PCP to 2, 6-dichloro-p-hydroquinone (2,6-DiCH) which is a common metabolic intermediate of the biodegradation of polychlorinated phenols . 2, 6-DiCH is degraded by PcpA from strain ATCC 39723, but the reaction end product has been misidentified as 6-chlorohydroxyquinol and has been elusive to detection . We report here the overproduction of PcpA in Escherichia coli and the demonstration of quantitative conversion of 2,6-DiCH to 2-chloromaleylacetate with the coconsumption of one equivalent O(2) and release of one equivalent Cl(-) by purified PcpA . On the basis of the reaction stoichiometry, the enzyme is proposed to be 2,6-DiCH 1,2-dioxygenase .

Naturwissenschaften, 1999 Oct, 86(10), 484 - 8
Fossil fuel biomarkers in sewage sludges: environmental significance
Payet C, Bryselbout C, Morel J, Lichtfouse E.
Fossil fuel biomarkers, or "molecular fossils," are specific organic substances found in coals, petroleums, and sedimentary rocks . They are formed during millions of years of sedimentary burial by geochemical alteration of biological molecules, such as cholesterol, under the effect of biodegradation, temperature, pressure, and mineral catalysis, to produce geochemically mature molecules, for example, aromatic steroids (Fig . 1) . Since fossil fuel biomarkers have a very specific molecular structure betraying fossil fuel sources, such markers should be useful in assessing the fossil fuel contamination of various modern media such as soils, plants, waters, and modern sediments . Here the identification of fossil fuel biomarkers of high geothermal maturity in sewage sludges provides evidence of the contamination of sludges by petroleum products . The most likely sources of contamination are contaminated vegetal food, road dust, and soil particles carried by rain water.springer.de/link/service/journals/00114/bibs/9086010/90860484 . htm</HEA

Mund Kiefer Gesichtschir, 1999 Sep, 3(5), 275 - 8
{Biodegradable miniplates (lactosorb) in cranio-osteoplasty--experimental results with the rapidly maturing, juvenile minipig}; Becker HJ et al.; As a passive intracranial transmission (PIT- effect) has been described for metallic osteosyntheses materials in the infant growing skull . Thereby the use of resorbable plates and screws might be an alernative fixation device in infant craniofacial surgery . For evaluating the biological behaviour, craniotomies were performed in the frontoorbital region of four infant minipigs, six weeks of age and 6.1 kg of weight . After turning and orthotopical repositioning the full thickness bone graft were fixed with resorbable plates and screws made of LactoSorb on the left side after epiperiosteal, on the right side after subperiosteal preparation . The animals were sacrificed after 3, 6, 9 and 18 months . Histologically, a PIT- effect was detected similar to metallic microplates and screws being significant diminished after epiperiosteal preparation and plate positioning . The biodegradation was not affected by intraosseous translocation . Even in case of intrasinuidal transmission no inflammatory reactions werde observed . No contraindications for the clinical use of this specific PLLA-PGA copolymer could be found when implanted in the rapidly growing craniofacial bone surfaces.

Nucleic Acids Res, 2000 Jan 1, 28(1), 377 - 9
The University of Minnesota Biocatalysis/Biodegradation database: microorganisms, genomics and prediction; Ellis LB et al.; The University of Minnesota Biocatalysis/Biodegradation Database begins its fifth year having met its initial goals . It contains approximately 100 pathways for microbial catabolic metabolism of primarily xenobiotic organic compounds, including information on approximately 650 reactions, 600 compounds and 400 enzymes, and containing approximately 250 microorganism entries . It includes information on most known microbial catabolic reaction types and the organic functional groups they transform . Having reached its first goals, it is ready to move beyond them . It is poised to grow in many different ways, including mirror sites; fold prediction for its sequenced enzymes; closer ties to genome and microbial strain databases; and the prediction of biodegradation pathways for compounds it does not contain.

Lett Appl Microbiol, 1999 Oct, 29(4), 242 - 5
Enhanced biodegradation of phenanthrene by a marine bacterium in presence of a synthetic surfactant; Cuny P et al.; The biodegradation of phenanthrene by the marine strain Sphingomonas sp . 2MPII (DSMZ 11572) was enhanced by the solubilizating properties of the nonionic surfactant Tween 80 . After 197 h of incubation, 85 +/- 4% of the initial amount of phenanthrene (0.4 g l-1) was biodegraded in presence of Tween 80 (0.5 g l-1) as opposed to 52 +/- 5% without this synthetic surfactant . These results confirm that the activity of the strain 2MPII is limited by the bioavailability of the polycyclic aromatic hydrocarbon (PAH) substrate in the aqueous phase . Tween 80 appears to be efficient in increasing the bioavailability of hydrophobic compounds such as PAHs.

Chemosphere, 1999 Nov, 39(12), 2007 - 18
Evaluation of laboratory-made sludge for an anaerobic biodegradability test and its use for assessment of 13 chemicals; Kawahara K et al.; Laboratory-made sludge for a biogas based anaerobic biodegradability test was prepared as an alternative for digested sludge from wastewater treatment plants (WWTPs) . Biodegradation activities and background gas productions of digested sludge from various WWTPs were found to vary significantly depending on the source, which adversely affected test reliability . Subsequently, test conditions such as sludge concentration and sludge washing were examined with the laboratory-made sludge and a sludge concentration of 1.0 g-SS/L without washing was determined to be most suitable . Under these conditions, biodegradability tests were conducted for 13 select chemicals and their relative toxicities to methanogenic bacteria were evaluated . The results of biodegradability tests showed that chemicals with -OH and -CH2OH radicals were readily biodegraded and those with -Cl, -NO2, -NH2, -SO3H and -CH3 had inhibited degradation responses m-nitriphenol and 2,4,6-trichlorophenol were highly toxic to methanogenic bacteria, with m-nitrophenol completely inhibiting methane fermentation as low as 20 mg/L.

J Biomater Sci Polym Ed, 1999, 10(9), 917 - 29
Mn-porphyrin derivatives as an antioxidant for medical devices; Ohse T et al.; It is well known that reactive oxygen species such as O*2- and H2O2 induce the biodegradation or cracking of medical devices in vivo or that they are released from inflammatory cells activated by devices to oxidize low-density lipoprotein . Therefore, the development of a novel antioxidant is required to eliminate the reactive oxygen species . In this paper, we report that Mn-porphyrin derivatives containing a macromolecular Mn-porphyrin are relatively stable compounds that can eliminate O*2- and/or H2O2 . The dismutation of O*2- in the porphyrins was determined using a cytochrome c-assay by the xanthine/xanthine oxidase system and using the stopped-flow kinetic analysis technique . The possibility of porphyrins as scavengers of H2O2 was evaluated by in situ measurement with a Clark electrode . As a result, it has been found that Mn-porphyrin derivatives may be a vastly better scavenger of reactive oxygen species in vivo.

Sci Total Environ, 1999 Sep 30, 237-238, 329 - 50
Evaluating the hazards of harmful substances carried by ships: the role of GESAMP and its EHS working group; Wells PG et al.; GESAMP's EHS working group, evaluation of the hazards of harmful substances carried by ships, contributed in the early 1970s to the chemical carriage provisions (Annexes II and III) of the MARPOL Convention, and after formal setup in 1974 under IMCO/IMO, has evaluated the hazards of approximately 2200 chemical substances transported worldwide by shipping . Hazard ratings for chemicals based on five criteria: bioaccumulation in marine organisms and tainting of seafood; damage to marine life defined by aquatic toxicity thresholds; acute hazard to human health, defined by oral intake; hazard to human health on the basis of skin or eye contact; and reduction of amenities, have been assigned by the working group experts (30 scientists from 11 countries overall) . The ratings are used by IMO committes to assign marine pollution categories under MARPOL 73/78, ensuring that shipping of chemicals in bulk or as packaged goods is conducted with due consideration for ship type, guidelines for discharges from tank cleaning and deballasting operations, packaging and labeling and response during accidents or loss . Since 1995, the working group has reviewed and revised its hazard criteria, and largely harmonized them with OECD . This will ensure compatibility of criteria and approaches across transport sectors . The criteria now include two measures of bioaccumulation, biodegradation, chronic toxicity to aquatic organisms, additional human health endpoints, and effects on marine wildlife and benthic habitats . The working group maintains a composite list of evaluations of hazards of harmful substances at IMO, London.

Int J Pharm, 1999 Dec 10, 192(2), 115 - 21
Proteolytic enzymes as a limitation for pulmonary absorption of insulin: in vitro and in vivo investigations; Shen Z et al.; In vitro biodegradation of insulin in lung cytosol and subcellular pellets of normal and diabetic rats was investigated . Rat lung was homogenized and subcellular fractions were isolated by ultracentrifugation . Degradations of {125I}-insulin after incubation with lung cytosol or subcellular pellets was determined using the trichloroacetic acid method . The results show that insulin is highly degraded in cytosol and subcellular pellets . Cytosolic insulin degradation was strongly inhibited by bacitracin or sodium cholate . The degradation of insulin in the lung cytosol from diabetic rats was significantly less than from normal rat . The lung protease activity reached a maximum at pH 7.4 . Enzyme inhibitors like bacitracin and sodium cholate noticeably enhanced the relative pharmacological bioavailability of insulin when given intratracheally with insulin to normal rats . Acidic insulin solutions (pH 3.0) had more pronounced hypoglycaemic effects than neutrol solution (pH 7.0) . These in vitro and in vivo results suggest that the proteolytic enzymes in the lung limit pulmonary delivery of insulin . The coadministration of protease inhibitors would be a useful approach for improving the pulmonary absorption of insulin.

Biochim Biophys Acta, 1999 Nov 16, 1472(3), 625 - 42
Spectroscopic properties of oxidation species generated in the lignin of wood fibers by a laccase catalyzed treatment: electronic hole state migration and stabilization in the lignin matrix; Barsberg S et al.; A laccase catalyzed oxidative treatment of wood pulp fibers has been found to induce unusual modifications of these fibers that are qualitatively different from those encountered when more severely degraded fibers are subjected to similar enzymatically catalyzed oxidative treatments . These results suggest that the physical/conformational state of the lignin of wood fibers determines which oxidation pathways dominate in a given oxidative treatment, leading to different lignin modifications depending on both the chemical and the physical structure of the lignin polymer . Spectroscopic measurements (ESR, IR, UV-Vis and fluorescence) show that the laccase treatment results in the formation of two different species in the dried fibers: one is interpreted as chemically transformed (via oxygen) lignin products, and the other as initial oxidation radicals which have gained stabilization against transformation into the first mentioned products via a migration mechanism . It is argued that these initial radicals may likely be cation radical (or hole state) parts in lignin . The migration mechanism is identified with site-to-site transfer or 'hopping' via electron transfer and it is postulated that this mechanism 'carries' cation radical parts of the lignin, produced at the surface of the fiber, into parts of the lignin where chemical transformation pathways are suppressed due to the lignin conformational state . The possible existence of such a migration mechanism, the relative dominance of which should depend sensitively on the polymer conformational state, may have implications for the biogeneration and biodegradation of lignin as well as for oxidative treatments of non-natural conjugated polymers.

FEBS Lett, 1999 Nov 12, 461(1-2), 115 - 9
Peroxyl radicals are potential agents of lignin biodegradation; Kapich AN et al.; Past work has shown that the extracellular manganese-dependent peroxidases (MnPs) of ligninolytic fungi degrade the principal non-phenolic structures of lignin when they peroxidize unsaturated fatty acids . This reaction is likely to be relevant to ligninolysis in sound wood, where enzymes cannot penetrate, only if it employs a small, diffusible lipid radical as the proximal oxidant of lignin . Here we show that a non-phenolic beta-O-4-linked lignin model dimer was oxidized to products indicative of hydrogen abstraction and electron transfer by three different peroxyl radical-generating systems: (a) MnP/Mn(II)/linoleic acid, (b) arachidonic acid in which peroxidation was initiated by a small amount of H(2)O(2)/Fe(II), and (c) the thermolysis in air of either 4,4'-azobis(4-cyanovaleric acid) or 2,2'-azobis(2-methylpropionamidine) dihydrochloride . Some quantitative differences in the product distributions were found, but these were attributable to the presence of electron-withdrawing substituents on the peroxyl radicals derived from azo precursors . Our results introduce a new hypothesis: that biogenic peroxyl radicals may be agents of lignin biodegradation.

Biomaterials, 1999 Nov, 20(22), 2169 - 75
Vascularization effect of basic fibroblast growth factor released from gelatin hydrogels with different biodegradabilities; Tabata Y et al.; Biodegradable gelatin hydrogels were prepared through the glutaraldehyde crosslinking of acidic gelatin with an isoelectric point (IEP) of 5.0 and the basic gelatin with an IEP of 9.0 . The hydrogel water content was changed by the concentration of both gelatin and glutaraldehyde, used for hydrogel preparation . An aqueous solution of basic fibroblast growth factor (bFGF) was sorbed into the gelatin hydrogel freeze-dried to obtain a bFGF-incorporating gelatin hydrogel . Irrespective of the hydrogel water content, approximately 30% of the incorporated bFGF was released from the bFGF-incorporating acidic gelatin hydrogel, within the first day into phosphate-buffered saline solution at 37 degrees C, followed by no substantial release . Probably, the basic bFGF complexed with the acidic gelatin through poly-ion complexation would not be released under the in vitro non-degradation condition of gelatin . On the contrary, almost 100% of the incorporated bFGF was initially released from all types of basic gelatin hydrogels . This is due to the simple diffusion of bFGF because of no complexation between bFGF and the basic gelatin . When implanted subcutaneously into the mouse back, bFGF-incorporating acidic and basic gelatin hydrogels with higher water contents were degraded with time faster than those with lower water contents . Significant neovascularization was induced around the implanted site of the bFGF-incorporating acidic gelatin hydrogel . The induction period prolonged with the decrease in hydrogel water content . On the other hand, such a prolonged vascularization effect was not achieved by the bFGF-incorporating basic gelatin hydrogel and the hydrogel initially exhibited less enhanced effect, irrespective of the water content . These findings indicate that the controlled release of biologically active bFGF is caused by biodegradation of the acidic gelatin hydrogel, resulting in induction of vascularization effect dependent on the water content . It is possible that only the transient vascularization by the basic gelatin hydrogel is due to the initial large burst in bFGF release, probably because of the down regulation of bFGF receptor.

J Biomater Appl, 1999 Oct, 14(2), 192 - 209
In vivo tissue engineering: Part I . Concept genesis and guidelines for its realization; Zdrahala RJ et al.; A loss of function of an organ often represents a life-threatening situation . Transplantations are successful, but "replacement" availability, its compatibility with the host, and subsequent healing often pose serious questions . Tissue engineering, where a carefully prepared scaffold is populated, in vitro, by cells to form an artificial organ, addresses some of the problems mentioned above . Trauma associated with the implant introduction to the host often complicates the process . The novel concept of in vivo tissue engineering which is designed to mediate the healing and tissue regeneration process by providing an in vitro formed porous, microcellular scaffold is proposed . The scaffold (part or entire organ) is then populated by cells either spontaneously (the surrounding cells will spread and populate to inhabit the scaffold) or by cellular augmentation (encapsulated cells are delivered to this in statu nascendi scaffold) . Minimally traumatic arthroscopic surgery combined with a unique polymer delivery system is envisioned for the introduction of this implant to a site to be repaired . Such an approach will require the formation of polymer in-situ, in a reasonable time . The scaffold-forming polymers will be, in principle, biodegradable . We propose to utilize biodegradable polyurethane systems for in vivo tissue engineering . Diversity of their structure/property relationships, relative "ease" of their preparation, and excellent biocompatibility predetermine polyurethanes to be the materials of choice . This paper describes the genesis of this concept and potentials for its realization . It is intended to initiate and stimulate discussion among the related scientific disciplines to form a basis for this field . The synthesis, application, and biodegradation of selected polyurethanes and variety of its medical utilization will be discussed in upcoming papers.

Xenobiotica, 1999 Sep, 29(9), 873 - 83
Inhibition of rat hepatic cytochrome P450 activities by biodegradation products of 4-tert-octylphenol ethoxylate; Hanioka N et al.; 1 . The effects of some biodegradation products of 4-tert-octylphenol ethoxylate (OPEO), namely 4-tert-octylphenol (OP), 4-tert-octylphenol diethoxylate (OP2EO) and 4-tert-octylphenol monocarboxylate (OPIEC) on the kinetics of cytochrome P450 (P450) -dependent monooxygenases in rat liver microsomes have been studied . 2 . Testosterone 16beta-hydroxylase (TS16BH), testosterone 2alpha-hydroxylase (TS2AH) and testosterone 6beta-hydroxylase (TS6BH) activities were extensively inhibited by OP at 100 microM (56.0-90.3%) . Inhibition was competitive for all P450-dependent monooxygenases . Ki(s) of TS16BH, TS2AH and TS6BH from Lineweaver-Burk plots were 6.37, 3.38 and 34.8 microM respectively . 3 . The activities of acetanilide 4-hydroxylase (AA4H), 7-ethoxycoumarin O-deethylase (ECOD) and bufuralol 1'-hydroxylase (BF1'H) were also effectively inhibited by OP at 100 microM (48.6-56.0%) . The inhibition of these P450-dependent monooxygenases was non-competitive, and Ki(s) (50.1-63.90 microM) were higher than those of TS16BH, TS2AH and TS6BH . 4 . OP2EO also inhibited AA4H, ECOD, TS16BH, TS2AH, BF1'H and TS6BH activities by 38.7-69.3% at 100 microM, although the inhibition rates were slightly lower than those for OP . K(i)s were 14.4-106 microM, and the inhibition was of mixed type (AA4H and ECOD), competitive (TS16BH, TS2AH and TS6BH) and non-competitive (BF1'H) . 5 . Testosterone 7alpha-hydroxylase (TS7AH), 4-nitrophenol 2-hydroxylase (4NP2H) and lauric acid omega-hydroxylase (LAOH) activities were only slightly affected by OP and OP2EO . 6 . The ability of OP1EC to inhibit P450-dependent monooxygenase activities was generally weaker than that of OP and of OP2EO: Ki >200 microM . 7 . These results suggest that OPEO biodegradation products interact with constitutive P450 isoforms, CYP1A2, CYP2A2, CYP2B2, CYP2C11 and CYP3A2 in rat liver in vitro (OP > OP2EO > OP1EC), and that the mechanism of this interaction differs depending on the compound and P450 isoform.

J Am Soc Mass Spectrom, 1999 Nov, 10(11), 1152 - 6
Determination of 3,3'-dichlorobenzidine and its degradation products in environmental samples with a small low-field Fourier transform ion cyclotron resonance mass spectrometer; Nyman MC et al.; 3,3'-Dichlorobenzidine (DCB) and its degradation products, 3-chlorobenzidine (MCB) and benzidine, are of environmental concern because of their carcinogenic nature . The suitability of a small Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer for the analysis of these environmental contaminants in different types of matrices was explored . All the measurements were carried out by depositing the sample solution directly on a disk that was introduced into the mass spectrometer . This approach is very fast and simple because it requires no prior chromatographic separation or derivatization . Calibration curves determined by collecting 70-eV electron ionization mass spectra of neat samples yielded lower limits of detection of 29 and 17 pg (total amount on the solids probe) for DCB and benzidine, respectively (based on a signal to noise ratio of > or = 2:1), while chemical ionization with ammonia resulted in lower limits of detection of 21 pg for DCB and 9 pg for benzidine (total amount on the solids probe) . FT-ICR analysis of sediments collected from Lake Macatawa (Holland, MI) verified the presence of DCB in this complex, environmentally significant sample matrix . Laboratory experiments designed to probe biodegradation and photodegradation pathways showed that DCB undergoes sequential dehalogenation to yield MCB and then benzidine under exposure to microorganisms and under simulated tropospheric solar radiation . The ability of the FT-ICR to determine elemental compositions of compounds introduced as described above was demonstrated for one of the degradation products.

Chemosphere, 1999 Nov, 39(11), 1957 - 69
Biodegradation kinetics of surfactants in seawater; Quiroga JM et al.; In this paper, a general kinetic model for degradation processes of surfactants is proposed . The model equation is v = K2S2 + K1S + K0, where v is the substrate consumption rate in the biodegradation process, S is the surfactant concentration in the medium and K2, K1, and K0 are kinetic constants . From this general expression, different simplified equations can be obtained (where K0 = 0; K2 and K0 = 0; K2 = 0; K2 and K1 = 0), which are representative of the process for different operating conditions . This model was tested by measuring the degradation of two different surfactants (Sodium dodecyl benzene sulfonate, LAS; and Sodium dodecyl sulfate, DSNa) under two different temperatures (5 and 20 degrees C) . Values predicted by the model are close to experimental data obtained.

Chemosphere, 1999 Nov, 39(11), 1861 - 70
Toxic effect of surfactants and probable products of their biodegradation on methanogenesis in an anaerobic microbial community; Shcherbakova VA et al.; Surfactants used in household and various industries, are rather toxic; therefore, the accumulation of these compounds in the environment through wastewaters has challenged the problem of their biodegradation . In this research, an attempt was made to assess the toxic effect of various surfactants and the likely products of their biodegradation on the acetoclastic methanogens of an anaerobic microbial community . Among the substances investigated, cationic surfactants were found to be most toxic to methanogens: 154 mg/l alkamon DS and 345 mg/l catamin AB induced a 50% inhibition of methanogenesis . Toxicity studies of some aromatic and cyclic compounds, as the probable products of biodegradation of alkylbenzene sulfonate surfactants, showed that methanogenesis in the microbial community under study are rather tolerant to high concentrations of these compounds.

Biotechnol Bioeng, 1999 Dec 5, 65(5), 491 - 9
Multisubstrate biodegradation kinetics of naphthalene, phenanthrene, and pyrene mixtures; Guha S et al.; Biodegradation kinetics of naphthalene, phenanthrene and pyrene were studied in sole-substrate systems, and in binary and ternary mixtures to examine substrate interactions . The experiments were conducted in aerobic batch aqueous systems inoculated with a mixed culture that had been isolated from soils contaminated with polycyclic aromatic hydrocarbons (PAHs) . Monod kinetic parameters and yield coefficients for the individual compounds were estimated from substrate depletion and CO(2) evolution rate data in sole-substrate experiments . In all three binary mixture experiments, biodegradation kinetics were comparable to the sole-substrate kinetics . In the ternary mixture, biodegradation of naphthalene was inhibited and the biodegradation rates of phenanthrene and pyrene were enhanced . A multisubstrate form of the Monod kinetic model was found to adequately predict substrate interactions in the binary and ternary mixtures using only the parameters derived from sole-substrate experiments . Numerical simulations of biomass growth kinetics explain the observed range of behaviors in PAH mixtures . In general, the biodegradation rates of the more degradable and abundant compounds are reduced due to competitive inhibition, but enhanced biodegradation of the more recalcitrant PAHs occurs due to simultaneous biomass growth on multiple substrates . In PAH-contaminated environments, substrate interactions may be very large due to additive effects from the large number of compounds present .

Biotechnol Prog, 1999 Oct 1, 15(5), 804 - 816
Substrate and Enzyme Characteristics that Limit Cellulose Hydrolysis; Mansfield SD et al.; The ability and, consequently, the limitations of various microbial enzyme systems to completely hydrolyze the structural polysaccharides of plant cell walls has been the focus of an enormous amount of research over the years . As more and more of these extracellular enzymatic systems are being identified and characterized, clear similarities and differences are being elucidated . Although much has been learned concerning the structures, kinetics, catalytic action, and interactions of enzymes and their substrates, no single mechanism of total lignocellulosic saccharification has been established . The heterogeneous nature of the supramolecular structures of naturally occurring lignocellulosic matrices make it difficult to fully understand the interactions that occur between enzyme complexes and these substrates . However, it is apparent that the efficacy of enzymatic complexes to hydrolyze these substrates is inextricably linked to the innate structural characteristics of the substrate and/or the modifications that occur as saccharification proceeds . This present review is not intended to conclusively answer what factors control polysaccharide biodegradation, but to serve as an overview illustrating some of the potential enzymatic and structural limitations that invariably influence the complete hydrolysis of lignocellulosic polysaccharides.

Biomaterials, 1999 Oct, 20(20), 1897 - 908
Effect of filler content on the profile of released biodegradation products in micro-filled bis-GMA/TEGDMA dental composite resins; Shajii L et al.; This study assesses the effect of the filler content, in a micro-filled composite (0.04 microm), on the liberation of biodegradation products derived from two model composite systems . The materials were based on bis-phenyl glycidyl dimethacrylate (bis-GMA) and triethylenene glycol dimethacrylate (TEGDMA) monomers . The composites were produced using silica filler concentrations of 20 and 40%) by weight . Samples were incubated with either cholesterol esterase (CE) or phosphate buffer solutions (PBS) for 8, 16 and 32 days . Products were isolated by high-performance liquid chromatography (HPLC) and identified by mass spectrometry . The identified products included TEGDMA, 2,2-bis{4(2,3-hydroxypropoxy)-phenyl}propane (bis-HPPP) and triethylene glycol methacrylate (TEGMA) . Bis-HPPP was only produced in the presence of enzyme . The amount of isolated TEGMA, in both composite systems, was shown to be significantly higher for materials incubated with enzyme than their buffer counterparts (P < 0.05) . Between 0 and 8 days incubation with enzyme, significantly higher amounts of Bis-HPPP and TEGMA were generated with the lower filler model material (composite-20) than the higher filled composite (composite-40), while the opposite effect was observed between 8 and 16 days . The data indicate that biodegradation product release profiles are dependent on the filler/resin ratios, and suggests that this parameter should be considered when assessing product release for biocompatibility issues pertaining to dental composite systems.

Prog Neuropsychopharmacol Biol Psychiatry, 1999 Jul, 23(5), 915 - 28
Dose- and age-dependent alterations in choline acetyltransferase (ChAT) activity, learning and memory, and thyroid hormones in 15- and 30-day old rats exposed to 1.25 or 12.5 PPM polychlorinated biphenyl (PCB) beginning at conception; Provost TL et al.; 1 . Polychlorinated biphenyls (PCB) were released into the environment through improper disposal for decades, causing widespread contamination . Slow biodegradation and lipophilic properties of PCB caused its persistence and concentration through food webs . Exposure to these environmental contaminants through maternal transfer during early development has been associated with neurological and endocrinological alterations in several different organisms . 2 . The present study extended a preliminary investigation which suggested low level exposure to PCB altered acetylcholine biosynthesis enzyme, choline acetyltransferase (ChAT), activity in the hippocampus and basal forebrain and caused aberrations in thyroid hormone and behavior . 3 . Dietary exposure of 15-day-old animals to 1.25 ppm of Aroclor 1254 (LPCB) during gestation and lactation significantly elevated ChAT activity in both areas of the brain . Animals exposed to 12.5 ppm of Aroclor 1254 (HPCB) until 15 days of age demonstrated significant elevations of ChAT activity in the basal forebrain . Thyroxine (T4) concentrations were slightly elevated in 15-day-old LPCB animals and significantly depressed in HPCB exposed pups; triiodothyronine (T3) concentrations were not altered . 4 . At 30 days both LPCB and HPCB treatment groups displayed significantly depressed ChAT activity in both areas of the brain . T3 and T4 concentrations were subnormal, although T4 was not significantly depressed in LPCB animals . 5 . In the Morris water maze all animals, when tested between 25 and 29 days of age, improved their latency time to the platform over 10 spatial learning trials . However, when combined means of trials 8-10 were compared, HPCB exposed animals had significantly increased latency time to the podium compared to control and LPCB animals.

Appl Environ Microbiol, 1999 Oct, 65(10), 4357 - 62
Biodegradation of pentachlorophenol in a continuous anaerobic reactor augmented with Desulfitobacterium frappieri PCP-1; Tartakovsky B et al.; In this work, a strain of anaerobic pentachlorophenol (PCP) degrader, Desulfitobacterium frappieri PCP-1, was used to augment a mixed bacterial community of an anaerobic upflow sludge bed reactor degrading PCP . To estimate the efficiency of augmentation, the population of PCP-1 in the reactor was enumerated by a competitive PCR technique . The PCP-1 strain appeared to compete well with other microorganisms of the mixed bacterial community, with its population increasing from 10(6) to 10(10) cells/g of volatile suspended solids within a period of 70 days . Proliferation of strain PCP-1 allowed for a substantial increase of the volumetric PCP load from 5 to 80 mg/liter of reaction volume/day . A PCP removal efficiency of 99% and a dechlorination efficiency of not less than 90.5% were observed throughout the experiment, with 3-Cl-phenol and phenol being observable dechlorination intermediates.

Biotechnol Bioeng, 1999 Nov 20, 65(4), 407 - 15
Phenol degradation by Ralstonia eutropha: colorimetric determination of 2-hydroxymuconate semialdehyde accumulation to control feed strategy in fed-batch fermentations; Leonard D et al.; Phenol biodegradation by Ralstonia eutropha was modeled in different culture modes to assess phenol feeding in biotechnological depollution processes . The substrate-inhibited growth of R . eutropha was described by the Haldane equation with a Ks of 2 mg/L, a Ki of 350 mg/L and a mumax of 0.41 h(-1) . Furthermore, growth in several culture modes was characterized by the appearance of a yellow color, due to production of a metabolic intermediate of the phenol catabolic pathway, 2-hydroxymuconic semialdehyde (2-hms) which was directly correlated to the growth rate and/or the phenol-degradation rate, because these two parameters are coupled (as seen by the constant growth yield of 0.68 g biomass/g phenol whatever the phenol concentration) . This correlation between color appearance and metabolic activity was used to develop a control procedure for optimal phenol degradation . A mass-balance equation modeling approach combined with a filtering step using an extended Kalman filter enabled state variables of the biological system to be simulated . A PI controller, using the estimation of the phenol concentration provided by the modeling step, was then built to maintain the phenol concentration at a constant set-point of 0.1 g/L which corresponded to a constant specific growth rate of 0.3 h(-1), close to the maximal specific growth value of the strain . This monitoring strategy, validated for two fed-batch cultures, could lead, in self-cycling fermentation systems, to a productivity of more than 19 kg of phenol consumed/m(3)/d which is the highest value reported to date in the literature . This system of monitoring metabolic activity also protected the bacterial culture against toxicity problems due to the transient accumulation of phenol .

Ecotoxicol Environ Saf, 1999 Sep, 44(1), 86 - 91
Bioavailability, biodegradation, and acclimation of Tetrahymena pyriformis to 1-octanol; Bearden AP et al.; Previous work has indicated that the ubiquitous freshwater ciliate Tetrahymena pyriformis acclimates to the presence of hydrophobic chemicals acting by nonpolar narcosis . Four explanations have been identified to explain this apparent acclimation: (1) genetic adaptation occurs resulting in a resistant population, (2) T . pyriformis quickly biodegrades hydrophobic chemicals resulting in a perceived acclimation response, (3) hydrophobic chemicals are not bioavailable, and (4) T . pyriformis contain an endogenous biochemical adaptation system which can quickly cause cellular changes resulting in acclimation . Results of biodegradation experiments indicated that the total extractable 1-octanol did not change over the duration of the experiments . Bioavailability experiments were performed using the solid-phase microextraction technique . Although there is a decrease in freely available concentrations of 1-octanol over a 2.5 log unit range of Tetrahymena population density, the freely available concentration is constant for the population densities used for population growth experiments . Genetic change is highly unlikely since acclimation occurs in less than the time required for one population division . It is hypothesized that the acclimation response seen in Tetrahymena results from partitioning of the chemical into the membrane followed by active changes in the membrane structure to restore homeostasis .

Appl Microbiol Biotechnol, 1999 Aug, 52(2), 255 - 60
Effect of surfactant solubilization on biodegradation of polychlorinated biphenyl congeners by Pseudomonas LB400; Billingsley KA et al.; A variety of commercial surfactants were tested to determine their effect on polychlorinated biphenyl (PCB) transformation by Pseudomonas LB400 . Initial tests determined that most surfactants were fully or partially able to solubilize the PCB congeners 2,5,2'-chlorobiphenyl (CBP), 2,4,2',4'-CBP, 2,3,5,2',5'-CBP and 2,4,5,2',4',5'-CBP, at concentrations above the surfactants' critical micelle concentration (CMC) . Surfactants were also found to have no negative effect on bacterial survival, as cell numbers were the same or higher after incubation in the presence of surfactants than after incubation without surfactants . A comparison of the extent of biotransformation of single PCB congeners by the bacterium revealed that, at surfactant concentrations above the CMC, the presence of an anionic surfactant promoted while nonionic surfactants inhibited PCB transformation, compared to a control with no surfactant . The rates of transformation of PCB congeners were also higher in the presence of the anionic surfactant compared to the control . The inhibitory effects of a nonionic surfactant, Igepal CO-630 at a concentration above its CMC, on transformation of 2,4,5,2',5'-CBP could be eliminated by diluting the surfactant/PCB solution to a concentration close to the surfactant CMC.

Appl Microbiol Biotechnol, 1999 Aug, 52(2), 251 - 4
Biodegradation of methyl violet by Pseudomonas mendocina MCM B-402; Sarnaik S et al.; Pseudomonas mendocina MCM B-402 was found to utilize a triphenylmethane dye, methyl violet as the sole source of carbon when incorporated in synthetic medium . Almost complete decolorization of methyl violet by P . mendocina was observed within 48 h of incubation at ambient temperature (28 +/- 2 degrees C) under aerated culture conditions, when the bacteria were inoculated into Davis Mingioli's synthetic medium at a concentration of 100 mg/l medium . Methyl violet was mineralized to CO2 through three unknown intermediate metabolites and phenol . The decolorization of the dye involved demethylation.

Biodegradation, 1999 Jun, 10(3), 193 - 200
Biodegradation of xylene and butyl acetate using an aqueous-silicon oil two-phase system; Gardin H et al.; A stable microbial population, consisting of seven bacterial strains and three yeast strains, was selected in batch cultures on a mixture of ortho and meta-xylene and butyl acetate as the sole source of carbon and energy . This population can completely degrade up to 10 g/L of a mixture of these xenobiotics (70% xylene and 30% butyl acetate wt/wt) in a two-phase aqueous-silicone oil system (70%/30% vol/vol) within 96 h, while for the usual one-phase system very low growth degradation rates were observed . Further organic solvents were tested and finally, silicon oil was selected as the best organic phase for such a two-phase system . With periodical pH adjustments to 6.0 in fed-batch mode, the culture showed a global degradation rate of 63 mg L-1 h-1.

Folia Microbiol (Praha), 1999, 44(1), 77 - 84
Fungal utilization of organophosphate pesticides and their degradation by Aspergillus flavus and A . sydowii in soil; Hasan HA; Fungal species were isolated which utilize organophosphate pesticides, viz . phosphorothioic (pirimiphos-methyl and pyrazophos), phosphorodithioic (dimethoate and malathion), phosphonic (lancer) and phosphoric (profenfos) acid derivatives . Pesticide degradation was studied in vitro and in vivo (soil) . Aspergillus flavus, A . fumigatus, A . niger, A . sydowii, A . terreus, Emericella nidulans, Fusarium oxysporum and Penicillium chrysogenum were isolated from pesticide-treated wheat straw . The number of A . sydowii colonies was significantly promoted by 1 mmol/L pirimiphos-methyl, pyrazophos, lancer, dimethoate and malathion when used as phosphorus sources and by pirimiphos-methyl and pyrazophos when used as carbon sources . The number of A . flavus colonies increased with 0.5 mmol/L lancer and malathion used as the only carbon sources . A . sydowii, A . niger, A . flavus, E . nidulans and F . oxysporum grew on, and utilized, 5 pesticides as phosphorus source and showed more than 50% mass growth . A . sydowii, A . flavus and F . oxysporum phosphatase hydrolyzed the pesticides suggesting that these species are important pesticide degraders . A . sydowii produced higher amounts of the phosphatase than A . flavus and F . oxysporum . The enzyme was highly active against pyrazophos, lancer and malathion used as the only sources of organic phosphate . A . flavus and A . sydowii phosphatases efficiently hydrolyzed pesticides at 300 ppm in soil, the degradation at 1000 ppm was lower . Mineralization of 1000 ppm pesticides in soil amended with wheat straw was higher than in nonamended soil . All added pesticides except profenfos were degraded within 3 weeks . Lyophilized adapted biomass of A . flavus and A . sydowii could thus be used for field biodegradation of these pesticides.

Chemosphere, 1999 Oct, 39(9), 1397 - 405
Effects of culture parameters on the degradation of 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4-dichlorophenol (2,4-DCP) by selected fungi . Groupe pour l'Etude du Devenir des Xénobiotiques dans l'Environnement (GEDEXE); Vroumsia T et al.; In order to enhance 2,4-D and 2,4-DCP degradation by four selected fungi (Cunninghamella elegans, C . echinulata, Rhizoctonia solani and Verticillium lecanii), three culture parameters (initial chemical concentration, amounts of glucose and nitrogen) were varied . The levels of both xenobiotics in the culture media were monitored by HPLC analysis after five days of cultivation . The best results were obtained at low initial concentration (20 mg.L-1 vs 100) and with low amounts of glucose (5 g.L-1 vs 10) and nitrogen (2.4 mM vs 24) . When these two elements were lacking from the culture media, biodegradation was not suppressed, but took place to a lesser extent . Thus, initial chemical concentration and amounts of carbon and nitrogen, in the culture medium, were shown to strongly influence the extent of 2,4-D and 2,4-DCP removal by fungi.

Res Microbiol, 1999 Jul-Aug, 150(6), 413 - 20
Biodegradation of phenylbenzoate and some of its derivatives by Scedosporium apiospermum; Claussen M et al.; Scedosporium apiospermum, a recently isolated phenol-degrading hyphomycete, was shown to be able to productively utilise the diaryl ester phenylbenzoate as its sole source of carbon and energy . The characterisation of degradation intermediates together with the detection of the corresponding catabolic enzymes in crude extracts enabled us to propose a pathway for the degradation of this diaryl ester . According to our results, an inducible esterase initiated the biodegradation of phenylbenzoate by hydrolysing the ester bond to yield stoichiometric amounts of phenol and benzoate . While phenol was catabolised via catechol and hydroxyhydroquinone, the benzoate was further degraded via the protocatechuate branch of the ortho-pathway . In addition, the fungus utilised p-tolylbenzoate and 4-chlorophenylbenzoate by employing similar catabolic sequences.

J Am Podiatr Med Assoc, 1999 Aug, 89(8), 392 - 7
Hydroxyapatite as a bone substitute; Mahan KT et al.; A bone substitute eliminates the need for autogenous and allogeneic bone grafting, along with the complications unique to each . Coralline hydroxyapatite is a synthetic bone void filler manufactured from marine coral, which has a natural trabecular structure similar to that of cancellous bone . While initial studies have been promising, the use of coralline hydroxyapatite may be limited in the foot and ankle owing to its inherent mechanical weakness and lack of biodegradation . In this retrospective study, 20 patients who received coralline hydroxyapatite implants were reviewed to determine associated complications and host reaction to the material . The results indicate that the material is biologically inert and safe to use as a small-defect filler in low-load applications . Long-term clinical trials are needed to determine the indications for this material in the foot and ankle.

Biodegradation, 1999 Apr, 10(2), 135 - 48
Biodegradation of dicyclopentadiene in the field; Stehmeier LG et al.; Dicyclopentadiene (DCPD) is formed during the pyrolysis of alkanes to produce olefins suitable for manufacturing synthetic polymers . DCPD has an irritating odor with a 5 ppb detection level that provides the impetus for remediation efforts . One method of destroying odors is to alter the structure of the chemical . This can be accomplished by biological oxidation using microorganisms . Field studies at two sites, where DCPD was a soil contaminant, indicated that biodegradation contributed significantly to DCPD removal . DCPD degradation was stimulated by decreasing bulk soil density and adding nitrogen and phosphorous nutrients . The presence of other easier degradable aromatic hydrocarbons may also be beneficial, suggesting that the process is cometabolic.

Biodegradation, 1999 Apr, 10(2), 93 - 104
Biodegradation of 2-methyl, 2-ethyl, and 2-hydroxypyridine by an Arthrobacter sp . isolated from subsurface sediment; O'Loughlin EJ et al.; A bacterium capable of degrading 2-methylpyridine was isolated by enrichment techniques from subsurface sediments collected from an aquifer located at an industrial site that had been contaminated with pyridine and pyridine derivatives . The isolate, identified as an Arthrobacter sp., was capable of utilizing 2-methylpyridine, 2-ethylpyridine, and 2-hydroxypyridine as primary C, N, and energy sources . The isolate was also able to utilize 2-, 3-, and 4-hydroxybenzoate, gentisic acid, protocatechuic acid and catechol, suggesting that it possesses a number of enzymatic pathways for the degradation of aromatic compounds . Degradation of 2-methylpyridine, 2-ethylpyridine, and 2-hydroxypyridine was accompanied by growth of the isolate and release of ammonium into the medium . Degradation of 2-methylpyridine was accompanied by overproduction of riboflavin . A soluble blue pigment was produced by the isolate during the degradation of 2-hydroxypyridine, and may be related to the diazadiphenoquinones reportedly produced by other Arthrobacter spp . when grown on 2-hydroxypyridine . When provided with 2-methylpyridine, 2-ethylpyridine, and 2-hydroxypyridine simultaneously, 2-hydroxypyridine was rapidly and preferentially degraded; however there was no apparent biodegradation of either 2-methylpyridine or 2-ethylpyridine until after a seven day lag . The data suggest that there are differences between the pathway for 2-hydroxypyridine degradation and the pathways(s) for 2-methylpyridine and 2-ethylpyridine.

Biodegradation, 1999 Apr, 10(2), 83 - 91
Transformation and mineralization of 2,4,6-trinitrotoluene (TNT) by manganese peroxidase from the white-rot basidiomycete Phlebia radiata; Van Aken B et al.; The degradation of the nitroaromatic pollutant 2,4,6-trinitrotoluene (TNT) by the manganese-dependent peroxidase (MnP) of the white-rot fungus Phlebia radiata and the main reduction products formed were investigated . In the presence of small amounts of reduced glutathione (10 mM), a concentrated cell-free preparation of MnP from P . radiata exhibiting an activity of 36 nkat/ml (36 nmol Mn(II) oxidized per sec and per ml) transformed 10 mg/l of TNT within three days . The same preparation was capable of completely transforming the reduced derivatives of TNT . When present at 10 mg/l, the aminodinitrotoluenes were transformed in less than two days and the diaminonitrotoluenes in less than three hours . Experiments with 14C-U-ring labeled TNT and 2-amino-4,6-dinitrotoluene showed that these compounds were mineralized by 22% and 76%, respectively, within 5 days . Higher concentrations of reduced glutathione (50 mM) led to a severe inhibition of the degradation process . It is concluded that Phlebia radiata is a good candidate for the biodegradation of TNT as well as its reduction metabolites.

Bone, 1999 Aug, 25(2 Suppl), 41S - 45S
Histological and biomechanical studies of two bone colonizable cements in rabbits; Lu JX et al.; We have developed two colonizable bone cements: the first is a partially resorbable bisphenol-alpha-glycidyl methacrylate (Bis-GMA)-based cement (PRC) and the second is a calcium phosphate cement (CPC) . PRC is composed of aluminous silanized ceramic and particles of a bioresorbable polymer embedded in a matrix of Bis-GMA . CPC consisted of tricalcium phosphate, monocalcium phosphate monohydrate, dicalcium phosphate dihydrate, and xanthane . Both cements were implanted into cavities drilled in rabbit femoral and tibial condyles . After 2, 4, 12, and 24 weeks of implantation, histological observations and biomechanical tests were performed . With CPC, a progressive osteointegration with a concomitant biodegradation in the presence of macrophages were observed . The mechanical study revealed a decrease of the compressive strength until the 4th week, followed by a slight increase . There was a general decrease in the elastic modulus with time . Moreover, by week 4, the histological study showed that the new bone was in direct contact with CPC margins . No inflammation was observed during the observation period . With PRC, the osteointegration as well as the biodegradation were slight, but its compressive strength was higher than that of cancellous bone and CPC (p < 0.05) at all observation periods . Its elastic modulus was greater than that of cancellous bone and CPC until the 4th week, then fell under the values of the cancellous bone.

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