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