Biodegradation

Mar Pollut Bull, 2004 Apr, 48(7-8), 671 - 8
Numerical simulation of organic chemicals in a marine environment using a coupled 3D hydrodynamic and ecotoxicological model; Kim DM et al.; For ecotoxicological risk assessment in a marine ecosystem, we constructed a coupled three-dimensional hydrodynamic and ecotoxicological model (EMT-3D), and applied it to Tokyo Bay . The model was calibrated with field data obtained in 2002 . The results of sensitivity analysis for dissolved Bisphenol A showed that biodegradation rate was the most important factor for concentration change . Bioconcentration coefficient was the most important factor for Bisphenol A in phytoplankton . Therefore, the parameters must be carefully considered in the modeling . The mass balance results showed that standing stocks of Bisphenol A in water, in particulate organic carbon and in phytoplankton are 7.85 x 10(4), 1.78 x 10(2) and 3.44 x 10(-1) g, respectively . With respect to flux, biodegradation in the water column had the highest value of 1.06 x 10(3) g/day, and next were effluent to the open sea, partition to particulate organic carbon, and bioconcentration in phytoplankton.

Chemosphere, 2004 May, 55(6), 915 - 25
Biodegradation of haloacetic acids by bacterial enrichment cultures; McRae BM et al.; Haloacetic acids (HAAs) are toxic organic chemicals that are frequently detected in surface waters and in drinking water distribution systems . The aerobic biodegradation of HAAs was investigated in serum bottles containing a single HAA and inoculated with washed microorganisms obtained from enrichment cultures maintained on either monochloroacetic acid (MCAA) or trichloroacetic acid (TCAA) as the sole carbon and energy source . Biodegradation was observed for each of the HAAs tested at concentrations similar to those found in surface waters and in drinking water distribution systems . The MCAA culture was able to degrade both MCAA and monobromoacetic acid (MBAA) with pseudo-first order rate constants of 1.06 x 10(-2) and 1.13 x 10(-2) l(mg protein)(-1) d(-1), respectively, for concentrations ranging from 10(-5) to 2 mM . The pseudo-first order rate constant for TCAA degradation by the TCAA culture was 6.52 x 10(-3) l(mg protein)(-1) d(-1) for concentrations ranging from 5.33 x 10(-5) to 0.72 mM . The TCAA culture was also able to degrade MCAA with the rate accelerating as incubation time increased . Experiments with radiolabeled HAAs indicated that the 14C was primarily converted to 14CO2 with minor incorporation into cell biomass . The community structure of the enrichment cultures was analyzed by both cultivation-dependent and cultivation-independent approaches . Denaturing gradient gel electrophoresis (DGGE) of the PCR-amplified 16S rRNA gene fragments showed that each of the two enrichment cultures had multiple bacterial populations, none of which corresponded to HAA-degrading bacteria cultivated on HAA-supplemented agar plates . This research indicates that biodegradation is a potential loss mechanism for HAAs in surface waters and in drinking water distribution systems.

Ground Water, 2004 Mar-Apr, 42(2), 258 - 67
Evaluation of volatilization as a natural attenuation pathway for MTBE; Lahvis MA et al.; Volatilization and diffusion through the unsaturated zone can be an important pathway for natural attenuation remediation of methyl tert-butyl ether (MTBE) at gasoline spill sites . The significance of this pathway depends primarily on the distribution of immiscible product within the unsaturated zone and the relative magnitude of aqueous-phase advection (ground water recharge) to gaseous-phase diffusion . At a gasoline spill site in Laurel Bay, South Carolina, rates of MTBE volatilization from ground water downgradient from the source are estimated by analyzing the distribution of MTBE in the unsaturated zone above a solute plume . Volatilization rates of MTBE from ground water determined by transport modeling ranged from 0.0020 to 0.0042 g m(-2)/year, depending on the assumed rate of ground water recharge . Although diffusive conditions at the Laurel Bay site are favorable for volatilization, mass loss of MTBE is insignificant over the length (230 m) of the solute plume . Based on this analysis, significant volatilization of MTBE from ground water downgradient from source areas at other sites is not likely . In contrast, model results indicate that volatilization coupled with diffusion to the atmosphere could be a significant mass loss pathway for MTBE in source areas where residual product resides above the capillary zone . Although not documented, mass loss of MTBE at the Laurel Bay site due to volatilization and diffusion to the atmosphere are predicted to be two to three times greater than mass loading of MTBE to ground water due to dissolution and recharge . This result would imply that volatilization in the source zone may be the critical natural attenuation pathway for MTBE at gasoline spill sites, especially when considering capillary zone limitations on volatilization of MTBE from ground water and the relative recalcitrance of MTBE to biodegradation.

Environ Int, 2004 Jun, 30(4), 509 - 17
Phytodegradation of extra heavy oil-based drill cuttings using mature reed wetland: an in situ pilot study; Ji GD et al.; Environmental contamination caused by extra heavy oil-based drill cuttings (DCs) is a major problem in the Liaohe Oilfield, northeastern China . To study the potential effectiveness of the mature reed wetland in removing extra heavy oil contained in drill cuttings, biodegradation of extra heavy oils and study of the effects on soil property and ecophysiological and quality indices of reeds were carried out in a 2-year in situ pilot experiment . In the wetland, four reed beds were used to treat drill cuttings in various loadings: 0 (control), 5, 20, and 40 kg/m(2), corresponding to 150, 600, and 1200 g/m(2) extra heavy oil hydrocarbons (HCs) . The obtained results demonstrate that the mature reed wetland was effective at degrading extra heavy oils without extra fertilization . Removal efficiencies of reed bed 2 in the 0- to 80-cm soil profile increased with time, from 90.1% (first harvest season) to 95.8% (second harvest season) . After 2 years, only 4.2% of the initial hydrocarbons residual was retained in the surface soil . There was no apparent adverse effects on the surface soil property during degradation of extra heavy oils and, actually, the deeper soil property and reed quality indices were improved at the end of the experiment . Phytotoxicity, resulting in reduction of reed yield, was observed in the most heavily treated beds in the first year . However, long-term reed yield recovered robustly . During the 2-year period, reed height and leaf number were slightly inhibited.

J Environ Sci Health A Tox Hazard Subst Environ Eng, 2004, 39(1), 1 - 17
Solid phase treatment of an aged soil contaminated by polycyclic aromatic hydrocarbons; Negri M et al.; Laboratory scale tests were carried out in order to evaluate the removal efficiency of polyaromatic hydrocarbons (PAHs) during the different biological treatments of a Manufacturing Gas Plant site aged soil, heavily contaminated by high molecular weight compounds . Biodegradation studies were carried out at nearly 25 degrees C in solid phase reactors . Three tests were performed, over a period of 100 days for each test . In the first test (P1-bioaugmentated), soil was mixed with wood chips and urea at the start of the treatment and after six weeks from the beginning of the test was also periodically inoculated (at 42, 54, 69, 82, and 96 days) with selected consortia of autochthonous PAH-degrading bacteria . The second test (P2-biostimulated) was performed similarly to the previous one, but without any inoculations . In the third test (P3-control) only soil was introduced . All systems were aerated daily and humidified at the occurrence . PAH concentration, total cultivable heterotrophs, PAH-degrading bacteria, mycetes, pH, ATP concentration, and enzymatic activities were monitored every two weeks during the treatments . Tests showed that nearly 50% of light (three rings) PAHs, 35% of benzo-PAHs and 40% of the total PAHs could be removed in the reactor P2 following 100 days of treatment . Lower removal efficiency could be observed for light PAHs (28%) in the inoculated reactor (P1) at the end of the treatment: comparable abatements were obtained for benzo- and total PAHs . In the reactor P3 (control), the concentration of all polyaromatic hydrocarbons was nearly always constant, suggesting that the physical losses were negligible during the solid phase treatments . Therefore the C to N ratio balance resulted to be the key factor in promoting the biodegradation process of all PAHs.

Prikl Biokhim Mikrobiol, 2004 Jan-Feb, 40(1), 57 - 61
{Use of Panus tigrinus fungi for production of pressed materials from cotton plant waste}; Kadimaliev DA et al.; Changes in the chemical composition of cotton plant stems used as a substrate for solid-phase cultivation of the fungus Panus tigrinus were studied as well as the effect of these changes on properties of the pressed materials made of these stems . During the first 3 days of growth, the fungus better consumed cellulose; then, the rate of cellulose consumption was comparable with that of lignin . Intensity and pattern of these changes depended on the age of inoculum . The rate of cotton plant waste biodegradation was higher when a 3-day-old incoculum was used . The pressed materials made of the raw stuff treated with a 3-day-old inoculum of P . tigrinus for 2-3 days displayed better characteristics . Annually, large amounts of lignocellulose stuff is lost while processing of agricultural waste: straw, awn, plant stems, etc . In the countries with developed cotton growing, the annual amount of only guza-paya (dry cotton plant stems) reaches several million tons . To solve this problem, bioconversion of these wastes is studied to manufacture useful products and materials.

J Contam Hydrol, 2004 Apr, 69(3-4), 173 - 94
Investigation of hydrogeologic processes in a dipping layer structure: 2 . Transport and biodegradation of organics; Alfnes E et al.; Numerical simulation tools have been used to study the dominating processes during transport of aromatic hydrocarbons in the unsaturated soil zone . Simulations were based on field observations at an experimental site located on a glacial delta plain with pronounced layered sedimentary structures . A numerical model for transport in the unsaturated zone, SWMS-3D, has been extended to incorporate coupled multispecies transport, microbial degradation following Monod kinetics and gas diffusive transport of oxygen and hydrocarbons . The flow field parameters were derived from previous work using nonreactive tracers . Breakthrough curves (BTC) from the hydrocarbon field experiment were used to determine sorption parameters and Monod kinetic parameters using a fitting procedure . The numerical simulations revealed that the assumption of homogeneous layers resulted in deviations from the field observations . The deviations were more pronounced with incorporation of reactive transport, compared with earlier work on nonreactive transport . To be able to model reasonable BTC, sorption had to be reduced compared to laboratory experiments . The initial biomass and the maximum utilisation rate could be adjusted to capture both the initial lag phase and the overall degradation rate . Nevertheless, local oxygen limitation is predicted by the model, which was not observed in the field experiment . Incorporation of evaporation and diffusive gas transport of the hydrocarbons did not significantly change the local oxygen demand . The main cause of the observed discrepancies between model and field are attributed to channelling as a result of small-scale heterogeneities such as biopores.

J Biomater Sci Polym Ed, 2004, 15(1), 1 - 24
Biodegradation of amino-acid-based poly(ester amide)s: in vitro weight loss and preliminary in vivo studies; Tsitlanadze G et al.; A systematic in vitro biodegradation study of regular poly(ester amide)s (PEAs) composed of naturally occurring hydrophobic alpha-amino acids, fatty diols and dicarboxylic acids using gravimetric (weight loss) method was carried out in the presence of hydrolases like alpha-chymotrypsin, lipase and a complex of proteases of Papaya . The last enzyme was used for modeling the catalytic action of nonspecific proteases . It was found that the PEAs, in the presence of enzyme solutions, were biodegraded by surface chemical erosion mechanism, according to the first-order kinetics . Spontaneous immobilization (adsorption) of the enzymes onto the PEAs surfaces was observed . The surface immobilized enzyme can also catalyze the chemical erosion of the PEAs . The enzymes could also be impregnated into the PEAs to make PEAs biochemically biodegraded, i.e . 'self-destructive', at a target rate . A comparison of in vitro biodegradation data of the PEAs with polylactide (PDLLA) showed that PEAs exhibited a far more tendency toward enzyme catalyzed biodegradation than PDLLA . A preliminary in vivo biodegradation study of selected PEA films in rats with and without lipase-impregnation showed that those PEAs were completely absorbed within 1-2 months post-implantation (for the lipase-impregnated ones) and 3-6 months (for the lipase-free ones) . These findings prompt us to suggest that these new PEAs may have a great potential for designing drug sustained/controlled release devices, as well as implantable surgical devices.

J Environ Sci Health A Tox Hazard Subst Environ Eng, 2004, 39(2), 409 - 20
Enhancement of carbon and nitrogen transformations during composting of municipal solid waste; Abu Qdais HA et al.; Appropriate management of municipal solid waste (MSW) is viewed as an integrated system encompassing waste minimization, recycling, and resource recovery . This has increased the interest in the composting process, in which the biodegradable portion of MSW is biologically converted into a valuable product that can be utilized as a soil conditioner or fertilizer . Effective operation of the composting process can be achieved by determining the optimal conditions for the controlling parameters in order to enhance the biological reactions during composting . Information on biodegradation rates are also essential for process design . Therefore, this study was conducted in order to examine the factors affecting process performance and transformation of essential elements of MSW such as carbon and nitrogen . A pilot study of in-vessel aerobic composting of MSW was carried out and the operating parameters, which affect biodegradation of carbonaceous and nitrogenous matter were studied using a specially designed rotating drum and a carbon-rich MSW . The effects of temperature, moisture content, and air flow rate were examined . The performance of the composting process was evaluated by measuring the carbon and nitrogen content during experiments, each of which lasted for 30 days . The study showed that enhanced transformations of carbon and nitrogen occur at 55 degrees C for temperature, 60% for moisture content, and 10L/kgh for air flow rate using the food-rich MSW generated in the Gulf countries.

J Environ Sci Health A Tox Hazard Subst Environ Eng, 2004, 39(2), 351 - 64
Assessment of Kuwait's Al-Qurain landfill using remotely sensed data; Kwarteng AY et al.; Kuwait's Al-Qurain landfill problem resulted from indiscriminate dumping of domestic and industrial waste in an abandoned quarry in the late 1970s and early 1980s . The landfill and surrounding areas were set aside for a government housing project without an environmental assessment of the impact of the landfill on the project . Inhabitants of the newly constructed housing area experienced persistent foul odor emanating from the landfill site . Since then, the issue has generated a lot of public interests, and several remediation measures have been adopted . In this preliminary study, several remotely sensed data consisting of Landsat Multispectral Scanner (MSS), Landsat Thematic Mapper (TM), IKONOS, and synthetic aperture radar (SAR) acquired between 1972 and 2000 were processed and assessed for their usefulness to study and monitor the landfill site . The imagery provided a historical perspective of how the areas had changed over the last 30 years . Other useful information of the landfill obtained from the satellite imagery included the spatial extent, spectral reflectance, surface temperature, and surface roughness . The landfill site showed higher surface temperatures compared to the immediate surrounding areas-a process that could accelerate the biodegradation and the release of landfill gases . Such dataset could be incorporated into a GIS for the long-term monitoring of the site.

Biomaterials, 2004 Aug, 25(17), 3359 - 68
Effects of periodate and chondroitin 4-sulfate on proteoglycan stabilization of ostrich pericardium . Inhibition of calcification in subcutaneous implants in rats; Arenaz B et al.; Chemical modification of biological materials used in the manufacture of cardiac valves tends to reduce the relatively high degree of biodegradation and calcification of the implanted bioprostheses . The most widely used treatment to reduce biodegradability of the valves is glutaraldehyde fixation . However, this treatment is potentially toxic and induces tissue calcification . In order to minimize these undesirable effects, we have analyzed the effect of a pre-fixation of endogenous proteoglycans and exogenous glycosaminoglycans, as well as the borohydride reduction influence on the different modified ostrich pericardium implants after subcutaneous implantation in rats . The presence of calcific deposits was detected in all implanted GA-fixed samples; however, calcification was highly reduced in both groups of periodate-prefixed materials, which showed also a very low Ca/P molar ratio . Borohydride post-treatment of these biomaterials resulted in a significant increase in calcium phosphate precipitation, with the appearance of calcium deposits mainly in an amorphous form even though X-ray diffraction allowed the detection of brushite- and apatite-like crystals . Regarding tissue stability, no significant differences were found among the borohydride-untreated implants but higher levels of matrix metalloproteinases were observed by gelatin zymography in the periodate pre-fixed materials . This increase was partially reduced by pre-fixation of exogenous chondroitin 4-sulfate . On the other hand, borohydride post-treatment not only increased calcification, but also reduced tissue stability and increased the presence of matrix-degrading activities.

Curr Microbiol, 2004 Jan, 48(1), 10 - 3
Biodegradation of DDT by a Pseudomonas species; Kamanavalli CM et al.; A bacterial strain capable of degrading 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane (DDT) was isolated from insecticide-contaminated soil by biphenyl enrichment culture and identified as a Pseudomonas species . The organism degraded DDT through the intermediate formation of 2,3-dihydroxy-DDT, which undergoes meta-ring cleavage, ultimately yielding 4-chlorobenzoic acid as a stable metabolite.

Water Res, 2004 Mar, 38(6), 1595 - 603
Assessment of enhancement in biodegradation of dichlorodiethyl ether (DCDE) by pre-oxidation; Kaludjerski M et al.; The objective of this study is to assess the enhancement in biodegradation of dichlorodiethyl ether (DCDE) by ozonation and Fenton treatment . Acclimated and non-acclimated sludge cultures were used to test the biodegradability of the preoxidized DCDE solutions by three different tests: Short-term and long-term respirometry through continuous monitoring of oxygen consumption, and the mid-term test in which the amount of remaining organic matter was measured by TOC and COD tests . These tests were applied to solutions of DCDE preoxidized at the levels of 25%, 50%, 75%, and 100% . The results indicated that the biodegradability of oxidized DCDE solutions improved substantially compared to non-oxidized solutions . Fenton-treated DCDE exhibited toxicity to microorganisms under long-term exposure . Higher levels of preoxidation of DCDE led to mineralization of larger amounts of organic matter during subsequent biodegradation . There was no significant difference in the rate of biodegradation of oxidized products by either acclimated or non-acclimated bacteria.

Shanghai Kou Qiang Yi Xue, 2000 Jun, 9(2), 73 - 5
{Experimental Study of Mandibular Reconstruction With Sr-HAP}; Liao DP et al.; OBJECTIVE:Different ration of Sr-HAP was implanted in animals to study the bioreactions in order to prepare for the clinical applications in future . METHODS:24 rabbits were divided into 3 groups for study.Bone defect of 6x12x4mm was made at the mandibular angle of rabbits and Sr-HAP of different proportion(10%,5%,0%) was applied to repair the defect.One group of animals were killed at 1 month, 3 months, 6 months to evaluate the biologic capacity with anatomy, tetracycline fluorescent marker and ration histology.RESULTS:Sr-HAP almost hadn't been rejected by hosts,and early after operation the new bone in the Sr-HAP was found with great quantities as the degradation of Sr-HAP much more than that in the pure HA,and the difference of bone quantity can be shown in statistics.New bone in 5% Sr-HAP looked more mature than those in 10% Sr-HAP with no statistic difference in quantity.Strong and bright fluorescent rings can be seen around Sr-HAP from the 3 months to 6 months . CONCLUSION:(1) Sr-HAP has a better biocompatibility,biodegradation than pure HA and an excellent osteoinductivity . (2) The ration of strontium isn't the key influencing the new bone quantity,total new bone quantity maybe associated with the degree of biodegradation . (3)The existence of Sr-HAP improves the total new bone quantity and prolongs the period of new bone increasing.

J Control Release, 2004 Feb 20, 95(1), 1 - 26
Genetically engineered polymers: status and prospects for controlled release; Haider M et al.; Genetic engineering methodology has enabled the synthesis of protein-based polymers with precisely controlled structures . Protein-based polymers have well-defined molecular weights, monomer compositions, sequences and stereochemistries . The incorporation of tailor-made motifs at specified locations by recombinant techniques allows the formation of hydrogels, sensitivity to environmental stimuli, complexation with drugs and nucleic acids, biorecognition and biodegradation . Accordingly, a special interest has emerged for the use of protein-based polymers for controlled drug and gene delivery, tissue engineering and other biomedical applications . This article is a review of genetically engineered polymers, their physicochemical characteristics, synthetic strategies used to produce them and their biomedical applications with emphasis on controlled release.

Tissue Eng, 2004 Jan-Feb, 10(1-2), 73 - 80
In vitro and in vivo degradation of mineralized collagen-based composite scaffold: nanohydroxyapatite/collagen/poly(L-lactide); Liao SS et al.; The objective of this article was to investigate the in vitro and in vivo biodegradation of a novel biomimetic bone scaffold composite, nanohydroxyapatite/collagen/poly(L-lactide), that could be used for bone tissue engineering . For evaluation of in vitro degradation specimens were immersed into 1% trypsin/phosphate-buffered saline solution at 37 degrees C . In vivo evaluation involved the implantation of samples into the posterolateral lumbar spine of rabbits, and the retrieved specimens were analyzed by Fourier transform-infrared spectroscopy . The results demonstrated that weight loss increased continuously in vitro with a reduction in mass of 19.6% after 4 weeks . During the experimental period in vitro, the relative rate of reduction of the three components in this material was shown to differ greatly: collagen decreased the fastest, from 40% by weight to 20% in the composite; hydroxyapatite content increased from 45 to 60%; and PLA changed little . The pore structure was maintained throughout the whole experimental period in vitro; however, the thickness of the walls of the pores decreased and the surface of the walls increased in roughness . In vivo, the ratio of collagen to hydroxyapatite appeared to be slightly higher near the transverse process than in the central part of the intertransverse process . This finding may have been due to new bone matrix formation extending from the transverse to the intertransverse process.

Chemosphere, 2004 Apr, 55(4), 525 - 31
Uncertainty analysis of parameters for modeling the transfer and fate of benzo(a)pyrene in Tianjin wastewater irrigated areas; Wang XL et al.; A Monte Carlo simulation for uncertainty analysis of three key parameters (local coal consumption rate Q(1L), dry deposition velocity of aerosol particulate Kp and biodegradation rate of benzo(a)pyrene in soil and sediment K(R3)) was conducted in this study . Results of the simulation indicate that the three parameters were influenced by uncertainty and that all equilibrium concentrations in the four bulk compartments and various sub-compartments were log-normally distributed . However, the results also indicated that among the six primary transfer fluxes, erosion associated with solids in soil and deposition associated with solids in water, along with output from sewers were also log-normally distributed, while deposition from air to soil and biodegradation in soil and sediment followed normal distributions . The effect of uncertainty on the model results of the three key parameters was derived using a comparison of upper and lower of confidence interval boundaries at the 95% level of confidence . The results reveal that uncertainty in the key parameters had a more significant influence on equilibrium concentrations of the chemical in the bulk compartments of soil and sediment than on concentrations in the other two bulk compartments, various sub-compartments and the six predominant transfer fluxes.

Arch Oral Biol, 2004 Apr, 49(4), 305 - 11
Effect of glutaraldehyde on the humoral immunogenicity and structure of porcine dermal collagen membranes; Wu KJ et al.; OBJECTIVES: Our previous studies showed that the biodegradation rate of cross-linked porcine dermal collagen membrane (PDCM) could be retarded without changing its biocompatible character . The purpose of this study was to assay the humoral immune response of PDCM reconstitute with glutaraldehyde (GA) and observe their surface architectures . METHODS: PDCM reconstituted with GA (0, 0.01, 0.05, and 3%) was implanted in 30 Sprague-Dawley rats . Sample sera were collected 3, 6, and 9 weeks after surgery and assayed with ELISA . The architectures of PDCMs were observed under SEM (100x) . RESULTS: The study showed that non cross-linked PDCM induced the highest immune response than any other cross-linked PDCMs (by optical density (OD) values, P<0.05) . It also possessed the most active cross-reactivity to the serum of rats from any other PDCMs groups (by Sheffe test, P<0.05) . The surface architectures observed under SEM presented four structures: fibrillar, porous, channeled, and sheet-like structures as PDCM was conditioned with 0, 0.01, 0.05, and 3% GA, respectively . CONCLUSIONS: Resulting from the study are that changing the concentration of GA can modulate the surface characters of PDCMs and change their immunogenicity . Reconstitution of PDCM may not change the conformation of antigenic determinants of PDCM but rather hinder the epitopes by changing the surface stereo structure of this collagen.

Biomacromolecules, 2004 Mar-Apr, 5(2), 596 - 602
Biodegradation of chemically modified flax fibers in soil and in vitro with selected bacteria; Modelli A et al.; The extent and rate of degradation of flax (Linum usitatissimum) fibers, both in the native state and after surface chemical modification (acetylation or poly(ethylene glycol), PEG, grafting), was investigated under laboratory conditions in two different biodegrading environments . Degradation of the fibers under aerobic conditions by the action of the microorganisms present in soil is assessed with the ASTM 5988-96 method by monitoring carbon dioxide evolution . In vitro biodegradation experiments were carried out by exposing the fibers to a pure culture of Cellvibrio fibrovorans bacteria and measuring the mass loss as a function of time . Despite the complexity of the system, the results of degradation in soil were satisfactorily reproducible, although the absolute rates were found to change in different experiments using the same soil . The degradation rate of acetylated fibers in soil nearly equals that of unmodified fibers, whereas in the pure culture, acetylated fibers biodegrade slower than native fibers . The opposite happens with the PEG-grafted fibers, which degrade slower than unmodified flax in soil and at a comparable rate upon in vitro exposure to the bacterial culture . The different biodegradation kinetics observed in the two biodegrading environments were attributed to differences of biocenoses, abiotic factors, and biodegradation assessing methods . Nevertheless, the final extent of biodegradation was the same for modified and unmodified fibers both in soil and in the pure culture, showing that the surface chemical modifications applied do not significantly affect biodegradability of the flax fibers.

Environ Sci Technol, 2004 Feb 15, 38(4), 1009 - 16
Aerobic biodegradation of two commercial naphthenic acids preparations; Clemente JS et al.; Naphthenic acids (NAs) have a variety of commercial uses including as emulsifiers and wood preservatives . They have been identified as being the main component responsible for the acute toxicity in produced waters in the oil sands operations in northeastern Alberta, Canada . NAs comprise a complex mixture of alkyl-substituted acyclic and cycloaliphatic carboxylic acids, with the general chemical formula CnH(2n+Z)O2, where n indicates the carbon number and Z specifies hydrogen deficiency from ring formation . In this study, commercial preparations of NAs were shown to be degraded in aerobic cultures from oil sands process-affected waters . High-performance liquid chromatography and gas chromatography-mass spectrometry (GC-MS) were used to monitor the concentrations and composition of the NA mixtures during biodegradation . Within 10 days of incubation, the NAs concentrations dropped from about 100 to <10 mg/L . This was accompanied by the release of about 60% of carbon from the NAs as CO2 and the reduction of toxicity of the culture supernatant, as measured by the Microtox assay . GC-MS results demonstrated that biodegradation changes the composition of the complex mixture of these NAs and that the lower molecular weight acids (with n = 5-13) were degraded more readily than the high molecular weight acids.

J Agric Food Chem, 2004 Mar 10, 52(5), 1220 - 3
Biodegradation of beta-cyfluthrin by fungi; Saikia N et al.; Five fungal species, namely, Trichoderma viride strain 5-2, T . viride strain 2211, Aspergillus niger, A . terricola, and Phanerochaete chrysoporium were screened for degradation study of beta-cyfluthrin . Each fungal species was allowed to grow in Czapek dox medium containing beta-cyfluthrin (5 mg/mL) as the major carbon source of the medium . The highest degradation of beta-cyfluthrin was observed by T . viride 5-2 (T(1/2) = 7.07 days), followed by T.viride 2211 (T(1/2) = 10.66 days) . The degradation of beta-cyfluthrin followed first-order kinetics with a fast degradation rate during first 7 days of growth of the fungi . In the case of T . viride strain 5-2, five degradation products were isolated after 20 days of growth of the fungi, out of which three products were identified as alpha-cyano-4-fluorobenzyl-3- (2,2-dichlorovinyl)-2,2-dimethyl cyclopropane carboxylate, alpha-cyano-4-fluoro-3-phenoxy benzyl alcohol, and 3(2,2-dichlorovinyl)-2,2-dimethyl cyclopropanoic acid.

Chemosphere, 2004 Apr, 55(3), 389 - 94
Novel method for determining pyrene biodegradation using synchronous fluorimetry; Zhang Y et al.; To study the biodegradation rate of pyrene dissolved in liquid medium supplemented with mineral salts, a synchronous fluorimetry (SF) method was established . The limit of detection for pyrene dissolved in mineral salts medium (MSM) was determined as 0.19 ng/ml with a relative standard deviation of less than 1.3% (n = 9) . The pyrene degrading rates of four bacterial strains were investigated using this method under the same experimental conditions . The degradation rates of the three active strains ranged from 76% to 87% after a 14-h incubation . The results were confirmed by the gas chromatography with a flame ionized detector (GC/FID) method . This implies that pyrene degradation can be directly monitored by the SF method without the solvent extraction of samples . The advantages of SF are that it is less laborious, faster, and less expensive than the GC/FID determination method with solvent extraction . The SF method provides a new tool for studying the degradation of polynuclear aromatic hydrocarbons (PAHs) in the natural environment and under experimental conditions.

Chemosphere, 2004 Apr, 55(3), 379 - 88
Biological and photochemical degradation rates of diethylenetriaminepentaacetic acid (DTPA) in the presence and absence of Fe(III); Metsarinne S et al.; The environmental fate of ethylenediaminetetraacetic acid (EDTA) has been extensively studied, while much less is known about the environmental behaviour of diethylenetriaminepentaacetic acid (DTPA) . In this study, it was confirmed that DTPA is persistent toward biodegradation . The biodegradability of DTPA was investigated in the absence and in the presence of Fe(III) by using CO2 evolution test and Manometric respirometry test . The CO2 evolution and oxygen uptake of iron-free (DTPA was added as free acid) and Fe(III)DTPA were less than in inoculum blank . Possible inhibitor effect was analysed by testing biodegradation of sodium benzoate with and without iron-free or Fe(III)DTPA in the Manometric respirometry test . Only slight inhibition was observed when DTPA was added as free acid . Photodegradation of iron-free DTPA and Fe(III)-DTPA complex was studied by using sunlight and UV radiation at the range 315-400 nm emitted by black light lamps . The results indicate that DTPA added as free acid degrades photochemically in humic lake water . Fe(III)DTPA was shown to be very photolabile in humic lake water in the summer; the photochemical half-life was below one hour . Photodegradation products were identified by the mass spectrometric technique (GC-MS) . It was shown that photodegradation of Fe(III)DTPA does not result in total mineralization of the compound . Diethylenetriaminetetraacetic acid, diethylenetriaminetriacetic acid, ethylenediaminetriacetic acid, N,N'- and/or N,N-ethylenediaminediacetic acid, iminodiacetate, ethylenediaminemonoacetic acid and glycine were identified as photodegradation products of Fe(III)DTPA . Based on these observations, we propose a photodegradation pathway for Fe(III)DTPA.

Environ Pollut, 2004 May, 129(2), 277 - 88
Attenuation reactions in a multiple contaminated aquifer in Bitterfeld (Germany); Heidrich S et al.; Large-scale contaminated sites with multiple contaminants in the groundwater present a challenge to risk assessment and remediation . Attenuation reactions take place in the subsurface and act to contain contaminants, but must be thoroughly investigated on a site-specific basis . Field data from monitoring wells at a contaminated industrial site in Bitterfeld, Germany, are presented and analyzed for evidence of the prevalent biodegradation reactions . The groundwater in the Tertiary aquifer is contaminated with large quantities of chlorinated aliphatic compounds, in addition to chlorobenzenes and BTEX . In this strictly anaerobic environment, geochemical indications for several microbial processes were found, including methanogenesis, sulfate and iron reduction as well as reductive dechlorination of the chlorinated hydrocarbons . Direct evidence for the latter degradation reaction was observed along the flowpath due to the appearance of intermediates and an increase in the degree of dechlorination.

Environ Toxicol Chem, 2004 Feb, 23(2), 313 - 24
Enhancing the attenuation of explosives in surface soils at military facilities: combined sorption and biodegradation; Fuller ME et al.; This research evaluated soil amendments designed to enhance the adsorption and biodegradation of explosives at military training facilities, thus minimizing their potential for transport to subsurface environments . Several carbon cosubstrates were tested in soil slurries for their ability to stimulate the biodegradation of 2,4,6-trinitrotoluene (TNT), hexahydro-1,3,5-trinitro-1,3,5-triazine (royal demolition exposive {RDX}), and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (high-melting explosive {HMX}) by indigenous soil microorganisms . Crude soybean oil and molasses stimulated mineralization of RDX (30-40%) and HMX (approximately 10%) . The TNT was not significantly mineralized in any of the treatments, but high-performance liquid chromatography (HPLC) analysis indicated extensive transformation of TNT to amino-containing compounds . The biodegradation of explosives was then examined in unsaturated soil microcosms amended with crude soybean oil and molasses combined with sphagnum peat moss and sawdust . Minimal TNT mineralization was observed, and HMX mineralization was only observed with molasses addition . In contrast, RDX mineralization was extensive in microcosms amended with soybean oil or molasses . The presence of peat moss decreased soybean oil-stimulated RDX mineralization by approximately 5%, but resulted in about 5% greater RDX mineralization compared with molasses only . Sawdust markedly decreased mineralization regardless of cosubstrate type . Mass balance results indicated that the formation of bound residues likely was occurring, especially for TNT . These results indicate that the application of inexpensive adsorbents and cosubstrates to soils may significantly improve the protection of groundwater resources underlying live fire ranges.

Water Sci Technol, 2004, 49(1), 53 - 9
Influence of the origin of the inoculum on the anaerobic biodegradability test; Moreno-Andrade I et al.; Five different sources of inocula were studied to determine its influence on biodegradability tests . Inocula were characterized determining granulometry, specific methanogenic activity, solids content, and volumetric sludge index . Also, the fermentative, aceticlastic, hydrogenophilic, OPHA, and sulfate-reducing groups were determined by the most probable number technique . Anaerobic biodegradability tests were conducted with two different substrates, one easy to degrade (glucose) and a toxic one (phenol) . The best performance, in terms of percent of biodegradation and lag time, for both substrates, was obtained with the inoculum from a brewery industry UASB . The results can be explained in terms of the initial activity of the inoculum . The influence of the significant variations found in the specific methanogenic activity of the five inocula studied is discussed, in terms of the microbial composition of the samples . The results emphasized the importance of the selection of an appropriate source of inoculum in order to obtain reliable results.

J Cell Physiol, 2004 Apr, 199(1), 8 - 19
Changes in macrophage function and morphology due to biomedical polyurethane surfaces undergoing biodegradation; Matheson LA et al.; Monocytes are recruited to the material surface of an implanted biomedical device recognizing it as a foreign body . Differentiation into macrophages subsequently occurs followed by fusion to form foreign body giant cells (FBGCs) . Consequently, implants can become degraded, cause chronic inflammation or become isolated by fibrous encapsulation . In this study, a relationship between material surface chemistry and the FBGC response was demonstrated by seeding mature monocyte-derived macrophages (MDMs) on polycarbonate-based polyurethanes that differed in their chemical structures (synthesized with poly(1,6-hexyl 1,2-ethyl carbonate) diol, and either (14)C-hexane diisocyanate and butanediol (BD) (referred to as HDI) or 4,4'-methylene bisphenyl diisocyanate and (14)C-BD (referred to as MDI)) and material degradation assessed . At 48 h of cell-material interaction, the FBGC attached to HDI were more multinucleated (73%) compared to MDI or the polystyrene (PS) control (21 and 36%, respectively) . There was a fivefold increase in the synthesis and secretion of a protein with an approximate molecular weight of 48 kDa and a pI of 6.1 (determined by two-dimensional gel electrophoresis) only from cells seeded on HDI . Immunoprecipitation confirmed that MSE and CE were synthesized and secreted de novo . Immunoblotting also showed an increase in secreted monocyte-specific esterase (MSE) and cholesterol esterase (CE) from cells seeded on HDI relative to PS and MDI . Significantly more radiolabel ((14)C) release and esterase activity were elicited by MDMs on HDI than MDI (P < 0.05) . The material that was more degradable (HDI), elicited greater protein synthesis and esterase secretion as well as more multinucleated MDMs than MDI, suggesting that the material surface chemistry modulates the function of MDM at the site of an inflammatory response to an implanted device .

Biodegradation, 2004 Feb, 15(1), 29 - 39
Potential for aerobic and anaerobic biodegradation of petroleum hydrocarbons in boreal subsurface; Salminen JM et al.; We studied the role of aerobic and anaerobic petroleum hydrocarbon degradation at a boreal, light-weight fuel and lubrication oil contaminated site undergoing natural attenuation . At the site, anoxic conditions prevailed with high concentrations of CH4 (up to 25% v/v) and CO2 (up to 18% v/v) in the soil gas throughout the year . Subsurface samples were obtained mainly from the anoxic parts of the site and they represented both the unsaturated and saturated zone . The samples were incubated in microcosms at near in situ conditions (i.e . in situ temperature 8 degrees C, aerobic and anaerobic conditions, no nutrient amendments) resulting in the removal of mineral oil (as determined by gas chromatography) aerobically as well as anaerobically . In the aerobic microcosms on average 31% and 27% of the initial mineral oil was removed during a 3- and 4-month incubation, respectively . In the anaerobic microcosms, on average 44% and 15% of the initial mineral oil was removed during a 12- and 10-month anaerobic incubation, respectively, and e.g . n-alkanes from C11 to C15 were removed . A methane production rate of up to 2.5 microg CH4 h(-1) g(-1) dwt was recorded in these microcosms . In the aerobic as well as anaerobic microcosms, typically 90% of the mineral oil degraded belonged to the mineral oil fraction that eluted from the gas chromatograph after C10 and before C15, while 10% belonged to the fraction that eluted after C15 and before C40 . Our results suggest that anaerobic petroleum hydrocarbon degradation, including n-alkane degradation, under methanogenic conditions plays a significant role in the natural attenuation in boreal conditions.

J Environ Sci (China), 2004, 16(1), 132 - 7
Evaluation of fungal potentiality for bioconversion of domestic wastewater sludge; Alam MZ et al.; This study was undertaken to screen the filamentous fungi isolated from its relevant habitats(wastewater, sewage sludge and sludge cake) for the bioconversion of domestic wastewater sludge . A total of 35 fungal strains were tested against wastewater sludge (total suspended solids, TSS 1%-5% w/w) to evaluate its potentiality for enhancing the biodegradability and dewaterability using liquid state bioconversion(LSB) process . The strains were divided into five groups i.e . Penicillium, Aspergillus, Trichoderma, Basidiomycete and Miscellaneous, respectively . The strains WWZP1003, SCahmA103, SCahmT105 and PC-9 among their respective groups of Penicillium, Aspergillus, Trichoderma and Basidiomycete played potential roles in terms of separation (formation of pellets/flocs/filaments), biodegradation(removal of COD) and filtration (filterability) of treated domestic wastewater sludge . The Miscellaneous group was not considered due to its unsatisfactory results as compared to the other groups . The pH value was also influenced by the microbial treatment during fermentation process . The filterability of treated sludge was improved by fungal treatment, and lowest filtration time was recorded for the strain WWZP1003 and SCahmA103 of Penicillium and Aspergillus groups respectively compared with other strains.

Biotechnol Lett, 2003 Dec, 25(24), 2089 - 92
Epifluorescence microscope methods for bacterial enumeration in a 4-chlorophenol degrading consortium; Pacheco CC et al.; Epifluorescence microscope methods, namely BacLight, direct epifluorescence filter technique and Rhodamine 123, consistently underestimated plate bacterial counts in a 4-chlorophenol degrading consortium . Cells capable of passing through 0.2 microm filters, referred as 'ultramicrocells', were found . Although cell counts were higher when traditional methods were used, BacLight and direct epifluorescence filter technique were convenient techniques for the systematic monitoring of bacteria involved in biodegradation processes, as results were consistent and available within a short time.

Biomaterials, 2004 Jul, 25(15), 2997 - 3004
Enhanced biological stability of collagen porous scaffolds by using amino acids as novel cross-linking bridges; Ma L et al.; Collagen porous scaffolds have been widely employed as a dermal equivalent to induce fibroblasts infiltration and dermal regeneration . To eliminate the disadvantageous drawback of the fast degradation speed, a cross-linking method was adopted by using a water-soluble carbodiimide, 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDAC) and N-hydroxysuccinimide (NHS) in the presence of amino acids (glycin, glutamic acid or lysine), which function as cross-linking bridge between collagen molecular chains . In vitro assessment of the biological stability of the cross-linked collagen scaffolds found that the collagenase biodegradation degree was greatly decreased when lysine was added, resulting in a more biological stable scaffold . On the other hand, the biodegradation degree was accelerated compared with the purely cross-linked when glutamic acid was added, while less influenced by glycin addition . By comparing the biodegradation degree of the scaffolds added with amino acids and their model compounds, i.e . adipic acid and hexane diamine, the key factor influencing the biological stability was further investigated . The results indicated that the crucial factor is dependent on the ratio of amino groups to carboxyl groups in the cross-linking system . At optimal ratio the lowest biodegradation degree is achieved . Scanning electron microscopy measurements prove that the three-dimensional structure of the scaffolds was largely preserved . Preliminary in vitro culture of fibroblasts in the collagen scaffold cross-linked with EDAC/NHS in the presence of lysine has shown that the original good cytocompatibility of collagen was retained.

Biotechnol Bioeng, 2004 Mar 20, 85(6), 580 - 8
Biodegradation kinetics of volatile hydrophobic organic compounds in cultures with variable fractional volumes; Tien TH et al.; An extension of the models developed by Guha and Jaffe (Biotechnol Bioeng {1996} 50:693-699) to describe the phenanthrene biodegradation kinetics for the cultures with variable fractional volumes is presented . Batch experiments were conducted with a culture capable of degrading the phenanthrene using a single culture vessel from which samples were withdrawn over time to monitor the disappearance of phenanthrene . For accurate measurement of phenanthrene concentrations, a sampling procedure designed for quantifying the sorption of phenanthrene onto glassware was also introduced . The Monod parameters were estimated by nonlinear regression analyses of simultaneous solutions to the substrate utilization/volatilization and Monod equations for growth of the cell mass . The results demonstrate that the models were able to be extended to phenanthrene-degrading cultures with variable fractional volumes . When the ratio between sampling volume and volume of the culture medium was relatively small, the parameters obtained were similar to those which would be obtained using constant fractional volumes of culture medium . It was also found that the model's fit to the phenanthrene disappearance data in this study were better than those obtained by Guha and Jaffe, implying that the sorption process of phenanthrene during the sampling period could significantly affect the measurement of phenanthrene concentrations . Failing to account for these losses led to less accurate measurements of substrate concentrations, which in turn resulted in a poor estimation of the parameters . The findings of this study reduce considerably the experimental work necessary in the estimation of Monod kinetic parameters for the purpose of modeling .

FEMS Microbiol Lett, 2004 Feb 9, 231(1), 13 - 7
Characterization of a novel carbofuran degrading Pseudomonas sp . with collateral biocontrol and plant growth promoting potential; Bano N et al.; The isolate NJ-101 obtained from agricultural soil was characterized and presumptively identified as Pseudomonas sp . The isolate exhibited efficient degradation of the insecticide carbofuran with a rate constant of 0.035 day(-1), following first-order rate kinetics . The ability of performing multifarious biological activities in tandem suggested the uniqueness of isolate NJ-101 . The ability to produce hydrogen cyanide and siderophore stipulated its role in biological control . Furthermore, the growth inhibition of Fusarium sp . validated the antagonistic activity of NJ-101 against the common phytopathogens . Concurrent production of indole acetic acid, and solubilization of inorganic phosphate revealed its plant growth promoting potential . Thus, the innate capability of this novel isolate for parallel biodegradation, biocontrol and plant growth promotion has significance in management of the agro-environmental and phytopathological problems.

Acta Pharm, 2003 Sep, 53(3), 187 - 97
Biodistribution of 131I-BSA loaded gelatin microspheres after peroral application to BALB/c mice--particle size study; Mladenovska K et al.; Biodistribution studies of radiolabelled 131I-BSA loaded gelatin microspheres were carried out on BALB/c mice after peroral administration . To two groups, radiolabelled 131I-BSA gelatin microspheres of different particle size, 1.2 +/- 1.1 microm and 7.0 +/- 1.2 microm, were administered orally . To the control group, a solution of 131I-BSA was administered orally as well . Biodistribution was followed periodically within 15 days as the percent of total radioactivity present in the stomach and small intestine with Peyer's patches and mesentery, in colon with Peyer's patches, appendix and mesentery, in liver, spleen, blood, kidney, lungs and heart . Preliminary in vitro biodegradation and drug release studies confirmed the potential of gelatin microspheres to protect the antigen of interest from enzymatic degradation in the gut, and to release it in a controlled manner . The biodistribution data confirmed that particle uptake into Peyer's patches and passage to the liver and spleen via the mesentery lymph supply and nodes increased with decreasing particle size.

Appl Environ Microbiol, 2004 Feb, 70(2), 1023 - 30
Induction of methyl tertiary butyl ether (MTBE)-oxidizing activity in Mycobacterium vaccae JOB5 by MTBE; Johnson EL et al.; Alkane-grown cells of Mycobacterium vaccae JOB5 cometabolically degrade the gasoline oxygenate methyl tertiary butyl ether (MTBE) through the activities of an alkane-inducible monooxygenase and other enzymes in the alkane oxidation pathway . In this study we examined the effects of MTBE on the MTBE-oxidizing activity of M . vaccae JOB5 grown on diverse nonalkane substrates . Carbon-limited cultures were grown on glycerol, lactate, several sugars, and tricarboxylic acid cycle intermediates, both in the presence and absence of MTBE . In all MTBE-containing cultures, MTBE consumption occurred and tertiary butyl alcohol (TBA) and tertiary butyl formate accumulated in the culture medium . Acetylene, a specific inactivator of alkane- and MTBE-oxidizing activities, fully inhibited MTBE consumption and product accumulation but had no other apparent effects on culture growth . The MTBE-dependent stimulation of MTBE-oxidizing activity in fructose- and glycerol-grown cells was saturable with respect to MTBE concentration (50% saturation level = 2.4 to 2.75 mM), and the onset of MTBE oxidation in glycerol-grown cells was inhibited by both rifampin and chloramphenicol . Other oxygenates (TBA and tertiary amyl methyl ether) also induced the enzyme activity required for their own degradation in glycerol-grown cells . Presence of MTBE also promoted MTBE oxidation in cells grown on organic acids, compounds that are often found in anaerobic, gasoline-contaminated environments . Experiments with acid-grown cells suggested induction of MTBE-oxidizing activity by MTBE is subject to catabolite repression . The results of this study are discussed in terms of their potential implications towards our understanding of the role of cometabolism in MTBE and TBA biodegradation in gasoline-contaminated environments.

J Bone Joint Surg Br, 2004 Jan, 86(1), 120 - 5
Biodegradation and biocompatability of a calcium sulphate-hydroxyapatite bone substitute; Nilsson M et al.; An injectable material consisting of calcium sulphate mixed with hydroxyapatite was investigated as a possible alternative to autograft in the restoration of bone defects . The material was studied both in vitro in simulated body fluid (SBF) and in vivo when implanted in rat muscles and into the proximal tibiae of rabbits . Variation in the strength and weight of the material during ageing in SBF was measured . Tissue response, material resorption and bone ingrowth were studied in the animal models . A good tissue response was observed in both the rat muscles and rabbit tibiae without inflammatory reactions or the presence of fibrous tissue . Ageing in SBF showed that during the first week carbonated hydroxyapatite precipitated on the surfaces of the material and this may enhance bone ingrowth.

Appl Microbiol Biotechnol, 2004 Jun, 64(5), 702 - 11 Epub 2004 Feb 05.
Quinone-respiration improves dechlorination of carbon tetrachloride by anaerobic sludge; Cervantes FJ et al.; The impact of humic acids and the humic model compound, anthraquinone-2,6-disulfonate (AQDS), on the biodegradation of carbon tetrachloride (CT) by anaerobic granular sludge was studied . Addition of both humic acids and AQDS at sub-stoichiometric levels increased the first-order rate of conversion of CT up to 6-fold, leading to an increased production of inorganic chloride, which accounted for 40-50% of the CT initially added . Considerably less dechlorination occurred in sludge incubations lacking humic substances . By comparison, very limited dechlorination occurred in sterile controls with autoclaved sludge . Accumulation of chloroform (1-10%) and dichloromethane (traces) also accounted for the CT converted . The accumulation of a chlorinated ethene, perchloroethylene (up to 9% of added CT), is also reported for the first time as an end-product of CT degradation . A humus-respiring enrichment culture (composed primarily of a Geobacter sp.) derived from the granular sludge also dechlorinated CT, yielding products similar to the AQDS-supplemented granular sludge consortium . The dechlorination of CT by the Geobacter enrichment was dependent on the presence of AQDS or humic acids, which were reduced during the assays . The reduced form of AQDS, anthrahydroquinone-2,6-disulfonate, was shown to cause the chemical reduction of CT when incubated in sterile medium . The results taken as a whole indicate that the formation of reduced humic substances by quinone-respiring microorganisms can contribute to the reductive dechlorination of CT.

Waste Manag, 2004, 24(2), 127 - 37
Field trial of a new aeration system for enhancing biodegradation in a biopile; Li L et al.; The influence of a new aeration system on the biopile performance was investigated . The purpose was to increase biodegradation efficiency by optimising airflow through the pile . During a 1-month field trial, the performance of a new system using two perforated vertical pipes with wind-driven turbines was compared with that of a standard pile configuration with two horizontal perforated pipes . Both piles were composed of a similar mix of diesel-contaminated soils, woodchips, compost and NPK fertiliser . Hydrocarbons were recovered using solvent extraction, and determined both gravimetrically and by gas chromatography . Total heterotrophs, pH and moisture content were also assessed . Air pressure measurements were made to compare the efficiency of suction in the pipes . Results at the end of the experiment showed that there was no significant difference between the two piles in the total amount of hydrocarbon biodegradation . The normalised degradation rate was, however, considerably higher in the new system than in the standard one, suggesting that the vertical venting method may have improved the efficiency of the biological reactions in the pile . The pressure measurements showed a significant improvement in the suction produced by the new aeration system . However, many factors other than the airflow (oxygen supply) may influence and limit the biodegradation rates, including moisture content, age of contaminants and the climatic conditions . Additional experiments and modelling need to be carried out to explore further the new aeration method and to develop criteria and guidelines for engineering design of optimal aeration schemes in order to achieve maximum biodegradation in biopiles.

Appl Microbiol Biotechnol, 2004 Aug, 65(3), 330 - 5 Epub 2004 Feb 03.
Reductive transformation of methyl parathion by the cyanobacterium Anabaena sp . strain PCC7120; Barton JW et al.; Organophosphorus compounds are toxic chemicals that are applied worldwide as household pesticides and for crop protection, and they are stockpiled for chemical warfare . As a result, they are routinely detected in air and water . Methods and routes of biodegradation of these compounds are being sought . We report that under aerobic, photosynthetic conditions, the cyanobacterium Anabaena sp . transformed methyl parathion first to o,o-dimethyl o-p-nitrosophenyl thiophosphate and then to o,o-dimethyl o-p-aminophenyl thiophosphate by reducing the nitro group . The process of methyl parathion transformation occurred in the light, but not in the dark . Methyl parathion was toxic to cyanobacteria in the dark but did not affect their viability in the light . Methyl parathion transformation was not affected by mutations in the genes involved in nitrate reduction in cyanobacteria.

Biotechnol Bioeng, 2004 Mar 5, 85(5), 561 - 7
Thermal and enzymatic pretreatment of sludge containing phthalate esters prior to mesophilic anaerobic digestion; Gavala HN et al.; The present study aimed at investigating the effect of thermal pretreatment of sludge at 70 degrees C on the anaerobic degradation of three commonly found phthalic acid esters (PAE): di-ethyl phthalate (DEP), di-butyl phthalate (DBP), and di-ethylhexyl phthalate (DEHP) . Also, the enzymatic treatment at 28 degrees C with a commercial lipase was studied as a way to enhance PAE removal . Pretreatment at 70 degrees C of the sludge containing PAE negatively influenced the anaerobic biodegradability of phthalate esters at 37 degrees C . The observed reduction of PAE biodegradation rates after the thermal pretreatment was found to be proportional to the PAE solubility in water: the higher the solubility, the higher the percentage of the reduction (DEP > DBP > DEHP) . PAE were slowly degraded during the pretreatment at 70 degrees C, yet this was probably due to physicochemical reactions than to microbial/biological activity . Therefore, thermal pretreatment of sludge containing PAE should be either avoided or combined with a treatment step focusing on PAE reduction . On the other hand, enzymatic treatment was very efficient in the removal of PAE . The enzymatic degradation of DBP, DEP, and DEHP could be one to two orders of magnitude faster than under normal mesophilic anaerobic conditions . Moreover, the enzymatic treatment resulted in the shortest half-life of DEHP in sludge reported so far . Our study further showed that enzymatic treatment with lipases can be applied to raw sludge and its efficiency does not depend on the solids concentration .

Res Microbiol, 2004 Jan-Feb, 155(1), 1 - 9
Molecular cloning, nucleotide sequencing and expression of genes encoding a cytochrome P450 system involved in secondary amine utilization in Mycobacterium sp . strain RP1; Trigui M et al.; Mycobacterium sp . strain RP1 degrades morpholine, piperidine, and pyrrolidine and is able to use these compounds as the sole source of carbon, nitrogen, and energy . Cytochrome P450 (MorA) is involved in the biodegradation of these secondary amines . A 3.9-PstI genomic DNA fragment, containing the gene encoding MorA, was cloned and sequenced . Four open reading frames were detected on this DNA fragment . The first encoded a cytochrome P450 designated as MorA which was the second member of the CYP151 family and was named CYP151A2 . The second open reading frame (morB) featured a {3Fe-4S} type of ferredoxin . A third gene (morC), exhibiting sequence identity to known reductases, and a fourth truncated gene encoding a putative glutamine reductase (orf1' ), were found downstream of morB . Recombinant MorA cytochrome P450 was purified to homogeneity from Escherichia coli . The purified enzyme was a monomeric soluble protein with an apparent Mr of about 45,000 . CYP151A2 catalyzed the ring cleavage of the secondary amines and the Vmax/KMapp values indicated that pyrrolidine is the preferred substrate for this monooxygenase.

Ecotoxicol Environ Saf, 2004 Feb, 57(2), 162 - 7
Residual toxicity after biodegradation: interactions among benzene, toluene, and chloroform; da Silva Nunes-Halldorson V et al.; A microbial enrichment originating from a pristine aquifer was found to aerobically biodegrade benzene and toluene, but not chloroform . This enrichment culture was used to study changes in pollutant toxicity as affected by biodegradative activity . Two assays for toxicity were used: (1) a 48-h acute toxicity test using the freshwater invertebrate Ceriodaphnia dubia and (2) microbial biodegradation activity as affected by the presence of mixed pollutants . At 20-ppm concentrations, toluene was significantly more toxic (99% mortality) to C . dubia than benzene (48% mortality) or chloroform (40% mortality) . Also at 20-ppm concentrations, but before biodegradation, toluene was significantly more toxic (88% mortality) to C . dubia than benzene (33% mortality) . After biodegradation of 98% of toluene and benzene, significant residual toxicity still remained in the bacterial supernatant: toluene-degraded supernatant caused 33% mortality in C . dubia and benzene-degraded supernatant caused 24% mortality . In the second toxicity assay, examining the effect of mixed pollutants on biodegradation activity, the presence of benzene slowed the biodegradation of toluene, but chloroform had no effect on either benzene or toluene biodegradation . Results indicate that significant toxicity remain after biodegradation and that halogenated aliphatic hydrocarbons may have little or no effect on aromatic hydrocarbon biodegradation at sites impacted by mixed pollutants.

Biomaterials, 2004 Jun, 25(13), 2687 - 93
Enzymatic degradation of starch-based thermoplastic compounds used in protheses: identification of the degradation products in solution; Araujo MA et al.; Apart from favourable physico-chemical and mechanical properties, the most important requirement for a biodegradable polymer to be used in medical applications is its biocompatibility and the non-cytotoxicity of its degradation products . Their combined effect should assure the safe material degradation under controlled kinetics . The present work analyses the degradation behaviour of blends of corn starch with poly(ethylene-vinyl alcohol) copolymer (SEVA-C) . The characterization included long-term degradation trials on simulated physiological solution with alpha-amylase up to 200 days . The degradation solutions were analysed by several techniques . High-performance liquid chromatography (HPLC) and colorimetric methods were used to monitor the liberation of carbohydrate as a consequence of starch hydrolysis by alpha-amylase . The hydration degree was followed by thermogravimetric analysis (TGA) . Several degradation products such as carbohydrates ranging from C6 to C18 were identified . After alpha-amylase action, biodegradation was more pronounced in the first 100 days, after which the biodegradation rate decreased probably due to the structure and porosity of the material . The action of alpha-amylase solely led to the starch degradation, in contrast with other assays without enzymes where no carbohydrates were found in the degradation solutions.

Biochem Biophys Res Commun, 2004 Feb 20, 314(4), 957 - 63
Anaerobic transformation of 2,4,6-TNT by bovine ruminal microbes; Fleischmann TJ et al.; Degradation of TNT by bovine rumen fluid, a novel source of anaerobic microbes, was investigated . Whole rumen fluid contents were spiked with TNT and incubated for a 24h time period . Supernatant samples taken at 0, 1, 2, 4, and 24h were analyzed by reverse-phase HPLC with diode array detection . Within 1h, TNT was not detectable and reduction products of TNT including 2-hydroxyl-amino-4,6-dinitrotoluene, 4-hydroxylamino-2,6-dinitrotoluene, and 4-amino-2,6-dinitrotoluene were present with smaller amounts of diamino-nitrotoluenes . Within 2h, only the diamino and dihydroxyamino-nitrotoluene products remained . After 4h, 2,4-diamino-6-nitrotoluene and 2,4-dihydroxyamino-6-nitrotoluene were the only known molecular species left . At 24h known UV absorbing metabolites were no longer detected, suggesting further transformation such as complete reduction to triaminotoluene or destruction of the aromatic ring of TNT may have occurred . TNT was not transformed at 24h in autoclaved and buffered controls . This study presents the first direct evidence of biodegradation of TNT by ruminal microbes.

Environ Sci Technol, 2004 Jan 15, 38(2), 609 - 16
Hydrogen and carbon isotope fractionation during anaerobic biodegradation of aromatic hydrocarbons--a field study; Steinbach A et al.; The aquifer of a former manufactured gas plant site, highly contaminated by dissolved monocyclic, heterocyclic, and polycyclic aromatic hydrocarbons, was studied to evaluate the applicability of carbon and hydrogen isotope fractionation to prove ongoing biodegradation of these compounds even in complex aquifer settings . The loss of toluene, o-xylene, p,m-xylene, and 2-methylnaphthalene was accompanied by a considerable carbon isotope fractionation . Additionally, a strong 2H enrichment in residual o-xylene was detected . All isotope fractionations observed could be related to established biochemical degradation mechanisms, each involving a C-H bond cleavage in the rate-determining step . In contrast, other compounds such as 1-methylnaphthalene, methylbenzofuran, and acenaphthene exhibited a uniform stable carbon isotope composition . However, a decrease in concentration for these compounds was observed in the flowpath of the aquifer . High threshold concentrations of acenaphthene downgradient indicate that this contaminant is, if at all, only marginally biodegraded . Detailed analyses of xylenes provided support that compound specific isotope analyses and subsequent application of the Rayleigh model may provide a valuable basis to distinguish between different biodegradation mechanisms as well as dissolution processes in heterogeneous aquifers.

Ann Bot (Lond), 2004 Mar, 93(3), 249 - 61 Epub 2004 Jan 28.
The function of the superficial root mat in the biogeochemical cycles of nutrients in congolese eucalyptus plantations; Laclau JP et al.; BACKGROUND AND AIMS: The importance of superficial root mats inside the forest floor for the nutrition of Amazonian rain forests has been extensively investigated . The present study was aimed at assessing the function of a root mat adherent to decomposing organic material observed in Eucalyptus plantations . METHODS: The development of the root mat was studied through micromorphological observations of thin litter sections, and the influence of soil microtopography and soil water repellency on root mat biomass was assessed in situ on an area of 5 m2 . In addition, input-output budgets of nutrients within the forest floor were established from measurements of litterfall, dissolved nutrients in gravitational solutions, and forest floor nutrient contents . KEY FINDINGS: The amounts of nutrients released during litter decay in this ecosystem during the period of study were, on average, 46, 3, 4, 19 and 17 kg ha-1 year-1 for N, P, K, Ca and Mg, respectively . The simultaneous measurements of the chemical composition of throughfall solutions and leachates beneath the forest floor showed a very quick uptake of nutrients by the root mat during the decomposition processes . Indeed, the solutions did not become noticeably enriched in nutrients during their passage through the holorganic layer, despite large amounts of elements being released during litter decay . The root mat biomass decreased significantly during the dry season, and a preferential development in microdepressions at the soil surface was observed . A strong water repellency observed in these depressions might enhance the ability of the roots to take up water and nutrients during the dry periods . CONCLUSIONS: The root mat was active throughout the year to catch the flux of nutrients from the biodegradation of the forest floor, preventing the transfer of dissolved nutrients toward deeper soil horizons . This mechanism is involved in the successful adaptation of this Eucalyptus hybrid in areas covered by 'climacic' savannas in Congo.

Int J Syst Evol Microbiol, 2004 Jan, 54(Pt 1), 131 - 9
Pseudonocardia chloroethenivorans sp . nov., a chloroethene-degrading actinomycete; Lee SB et al.; A bacterial strain, SL-1T, capable of degrading trichloroethene was isolated from a laboratory enrichment in the Department of Civil and Environmental Engineering, University of Washington, USA . The material in the enrichments was derived from a soil sample from Seattle, WA, USA . Strain SL-1T was capable of using phenol as a source of carbon and energy . Chemotaxonomic, morphological, physiological and phylogenetic analyses showed that strain SL-1T is a member of the genus Pseudonocardia . The ability of strain SL-1T to utilize phenol and degrade trichloroethene, as well as other phenotypic properties and the results from a 16S rRNA phylogenetic analysis, led to the proposal of a novel species, Pseudonocardia chloroethenivorans sp . nov . The type strain is SL-1T (=ATCC BAA-742T=DSM 44698T) . Trichloroethene and other chloroethenes are major pollutants at many environmental sites, and P . chloroethenivorans has biodegradation properties that should be of interest to environmental microbiologists and engineers.

Biomaterials, 2004 May, 25(12), 2309 - 17
Preparation and characteristics of hybrid scaffolds composed of beta-chitin and collagen; Lee SB et al.; Hybrid scaffolds composed of beta-chitin and collagen were prepared by combining salt-leaching and freeze-drying methods . The chitin scaffold used as a framework was easily formed into desired shapes with a uniformly distributed and interconnected pore structure with average pore size of 260-330 microm . The mechanical strength and the rate of biodegradation increased with the porosity, which could be modulated by the salt concentration . In addition, atelocollagen solution was introduced into the macropores of the chitin scaffold to improve cell attachment . Web-like collagen fibers fabricated between pores of chitin were produced by a 0.1 wt% collagen solution, whereas a 0.5 wt% collagen solution only coated the surface of the chitin scaffold . After 3 days of culture, fibroblasts cultured in collagen-coated scaffolds were attached at the place where the collagen was fabricated, whereas cells did not attach and aggregate on the scaffold of chitin alone . After 14 days, the fibroblasts showed a good affinity to and proliferation on all collagen-coated chitins.

Biomaterials, 2004 May, 25(10), 1787 - 93
Mutual influence of cholesterol esterase and pseudocholinesterase on the biodegradation of dental composites; Finer Y et al.; It has been demonstrated that human saliva contains cholesterol esterase (CE)- and pseudocholinesterase (PCE)-like hydrolase activities . While PCE has been shown to preferentially degrade triethylene glycol dimethacrylate (TEGDMA) and its derivatives, CE has a greater catalytic effect on the breakdown of bis-phenol-A-diglycidyl dimethacrylate (bisGMA) components in composite dental resins . The current study seeks to determine if there is a mutual influence between the different esterases with respect to the biodegradation of resin composite . Photopolymerized model composite resin samples (containing 60% by weight fraction of silanated barium glass filler) based on bisGMA/TEGDMA (bis) or urethane-modified bisGMA/TEGDMA/bisEMA (ubis) monomers were incubated in buffer, CE and/or PCE solutions (pH=7.0, 37 degrees C) for 8 and 16 days . The incubation solutions were analyzed for degradation products using high-performance liquid chromatography, UV spectroscopy and mass spectrometry . In the bis system, higher amounts (p<0.05) of a bisGMA derived product, bishydroxy-propoxyphenyl-propane (bisHPPP), were detected in the combined enzyme group as compared to the sum of the two individual enzyme groups . In the ubis system, similar comparisons showed that higher levels (p<0.05) of bisHPPP were detected in the combined group at 8 days while higher amounts (p<0.05) of a bisEMA derived product, ethoxylated bis-phenol A, were detected in the combined group at 16 days . The study concluded that CE and PCE act synergistically to increase the biodegradation of both composite resin materials.

J Chromatogr A, 2003 Dec 22, 1021(1-2), 11 - 7
Isolation of poly(propylene glycol)s from water for quantitative analysis by reversed-phase liquid chromatography; Rychlowska J et al.; Procedures for the isolation of poly(propylene glycol)s (PPGs) from a water matrix have been developed . Solid-phase extraction with an octadecylsilica cartridge and elution with methanol or with a graphitised carbon black cartridge and elution with a mixture of dichloromethane-methanol (4:1) or liquid-liquid extraction with chloroform were all suitable for model samples . However, only liquid-liquid extraction was suitable both for model and real environmental samples . Methods for reversed-phase liquid chromatographic determination of PPGs based on derivatisation and ultraviolet or fluorescence detection have been developed . Four derivatisation agents {3,5-dinitrobenzoyl chloride, phenyl isocyanate, 1-naphthoyl chloride and 1-naphthyl isocyanate (NIC)} were tested . Only NIC was found to give good reproducibility as well as a satisfactory detection limit . Finally, a method with liquid-liquid extraction with chloroform, derivatisation with NIC and liquid chromatographic separation with fluorescence detection was established . The developed method shows a highly correlated linearity of the analytical signals of particular homologues within a wide concentration range (approximately from 0.01 to 10 mg l(-1)) . The precision of measurements is satisfactory for homologues having 5-9 oxypropylene subunits and becomes worse with an increase in the number of oxypropylene subunits . The limit of detection is 2 microg l(-1) for the majority of homologues . The method is suitable for the isolation and quantitative determination of PPGs in river water samples and as a tool for biodegradation testing.

Aviakosm Ekolog Med, 2003, 37(5), 70 - 3
{Development of a technology for biodegradation of plant wastes in order to resolve the life support requirements of a Martian expedition}; Il'in VK et al.; A two-phase technology has been developed for biodegradation of plant wastes . On the first phase, wastes are subjected to anaerobic fermentation by specially selected microbial associations processing solid wastes into a liquid mixture of organic acids . On the second phase, methanogenic bacteria are used to produce biogas out of the liquid, which then can be dumped out into open space or utilized as a cold propellant.

Chin J Traumatol, 2004 Feb, 7(1), 18 - 24
Effect of nano-hydroxyapatite/collagen composite and bone morphogenetic protein-2 on lumbar intertransverse fusion in rabbits; Sun TS et al.; OBJECTIVE: To investigate the effect of nano-hydroxyapatite/collagen (nHA/collagen) composite as a graft extender and enhancer when combined with recombinant human bone morphogenetic protein-2 (rhBMP-2) on lumbar intertransverse fusion in rabbits . METHODS: Sixty-four adult female New Zealand white rabbits, aged 1 year and weighing 3.5-4.5 kg, underwent similar posterolateral intertransverse process arthrodesis and were randomly divided into 4 groups based on different grafts: autogenous cancellous bone alone (ACB group), nHA/collagen alone (HAC group), half autogenous cancellous bone and half nHA/collagen (ACB+HAC group) and nHA/collagen combined with rhBMP-2 (HAC+BMP group) . The fusion masses were analyzed by manual palpation, radiography, biomechanical testing and histological examination . RESULTS: Fusion was observed in 4 cases in the 6th week and in 5 cases in the 10th week after surgery in ACB group . No case showed fusion in HAC group . In ACB+HAC group, there was fusion in 3 cases in the 6th week and in 4 cases in the 10th week after surgery . In HAC+BMP group, fusion in 1 case was found in the 4th week, in 5 cases in the 6th week and in 6 cases in the 10th week after surgery . It suggested that ACB, ACB+HAC and HAC+BMP groups showed similar fusion ratio and mechanical strength in the 6th and 10th week after surgery . According to the microstructure analysis of the samples, nHA/collagen had no negative effect when implanted together with ilium autograft . In HAC+BMP group, new bone-like tissue was observed in the 2nd week postoperatively, and nearly all of the implanted composites were replaced by mature bone matrix and new bones in 10th week postoperatively . CONCLUSIONS: The nHA/collagen, especially combined with rhBMP-2, is a promising bone substitute, for it has quick biodegradation, fine bone-bending ability, and high osteoconductivity on posterolateral spinal fusion in rabbits.

Appl Microbiol Biotechnol, 2004 Jun, 64(5), 712 - 7 Epub 2004 Jan 16.
Biodegradation of alachlor by soil streptomycetes; Duraes Sette L et al.; Streptomycetes resistant to the herbicide alachlor {2-chloro-2',6'-diethyl- N-(methoxymethyl) acetanilide} were used in degradation assays to characterize the products of alachlor biodegradation . Of six strains tested, Streptomyces sp . LS166, LS177, and LS182 were able to grow at an alachlor concentration of 144 mg l(-1) and degraded approximately 60-75% of the alachlor in 14 days, as evaluated by high performance liquid chromatography . The alachlor biodegradation products were identified by gas chromatography-mass spectrometry based on mass spectral data and fragmentation patterns . All compounds detected in these assays were similar for all streptomycetes strains tested, and involved dechlorination with subsequent N-dealkylation and cyclization of the remaining N-substituent with one of the ethyl groups to produce indole and quinoline derivatives . The enzymatic pathway used by Streptomyces sp . LS182 did not generate DEA (2',6'-diethylaniline), a carcinogenic derivative of alachlor reported in other studies . Given the high degradation rates observed here, the Streptomyces strains tested may be useful in the degradation/detoxification processes of alachlor.

Anal Chem, 2004 Jan 15, 76(2), 399 - 403
Quenched phosphorescence as a detection method in capillary electrophoretic chiral separations . Monitoring the stereoselective biodegradation of camphorquinone by yeast; Garcia-Ruiz C et al.; Quenched phosphorescence detection of camphorquinone in cyclodextrin-based electrokinetic chromatography provides very favorable detection limits, i.e., 7 x 10(-)(7) M, 3 orders of magnitude lower than conventional UV absorption detection at 200 nm . The detection is based on the dynamic quenching by the analyte of the strong phosphorescence emission of brominated naphthalenesulfonate, under deoxygenated buffer solution conditions . This approach has been used to detect (1S)-(+)- and (1R)-(-)-camphorquinone after enantiomeric separation by CE . Although the use of the negatively charged carboxymethyl beta-cyclodextrin (CM-beta-CD) alone was not successful, the addition of a second, neutral cyclodextrin, alpha-CD, provided an adequate enantiomeric separation of camphorquinone . Using 25 mM borate buffer (pH 8.5) with 10 mM CM-beta-CD and 20 mM alpha-CD (applied voltage 20 kV, ambient temperature), the enantiomeric separation was performed in approximately 14 min . The chiral method was applied to monitor the stereoselectivity of the biotransformation of a racemic mixture of camphorquinone by yeast . It was found that the enantiomeric ratio calculated from the peak areas in the electropherogram (RSD = 5%) after 24 h of incubation decreased from 0.92 for the control solution (culture medium without yeast) to 0.24 for the culture medium; a similar ratio of 0.25 was observed for cell extract solutions . Therefore, racemic camphorquinone is enantioselectively degraded by yeast, the biodegradation of (1S)-(+)-camphorquinone being faster than that of the (1R)-(-)-enantiomer.

Biotechnol Lett, 2003 Nov, 25(22), 1905 - 11
Salicylate biodegradation by various algal-bacterial consortia under photosynthetic oxygenation; Munoz R et al.; Four green microalgae (Chlorella sorokiniana, Chlorella vulgaris, Scenedesmus obliquus and Selenastrum capricornutum), a wild Bolivian microalga strain and two cyanobacteria (Anabaena catenula and Microcystis aeruginosa) were compared for tolerance to salicylate, O2 production capacity and ability to support salicylate degradation by a Ralstonia basilensis strain in symbiotic microcosms with the microalgae . Microcystis aeruginosa had the highest tolerance to salicylate at 500 mg l(-1) and 1500 mg l(-1) but only produced 0.7 mg O2 l(-1) h(-1) in the absence of pollutant . Chlorella sorokiniana resisted salicylate at 1500 mg l(-1) with the highest O2 production in the absence of salicylate (26 mg l(-1) h(-1)) closely followed by the Bolivian microalga (23 mg l(-1) h(-1)) and Chlorella vulgaris (21 mg l(-1) h(-1)) . Selenastrum capricornutum and Anabaena catenula were completely inhibited by salicylate at 500 mg l(-1) . When inoculated with Ralstonia sp . and supplied with salicylate, Chlorella sorokiniana had the highest removal rate (19 mg l(-1) h(-1)), followed by the wild Bolivian strain (18 mg l(-1) h(-1)) and Chlorella vulgaris (14 mg l(-1) h(-1)).

Sheng Wu Yi Xue Gong Cheng Xue Za Zhi, 2003 Dec, 20(4), 746 - 9
{Studies on a kind of new biodegradable material--polycaprolactone and developments in medical area}; Zhang N et al.; Nowadays, there are more and more researches on characters and applications of polycaprolactone (PCL) . This paper reviews the researches of polycaprolactone, including its synthesis, physical and chemical properties, biodegradation, absorption properties, and its applications in clinical use and drug delivery systems . PCL can be from open ring polymerizaion . It is a kind of semi-crystalline polymer, and has good flexibility . The degradation reaction of PCL is hydrolysis . PCL is not cumulated in the body, and can be totally excreted . It can be used as suture, material for fixation of bone fracture, vector of drug, etc . PCL is widely used in medical area because of its safety, low toxicity, biodegradability.

Appl Microbiol Biotechnol, 2004 Jan, 63(4), 460 - 5 Epub 2003 Mar 26.
Bioavailability of pentachlorophenol to acclimatised bacteria under batch and flow-through conditions; Dudal Y et al.; Biodegradation of organic contaminants in multi-phase systems, such as soils and aquifers, is often limited by the extent and the rate of contaminant sorption onto the solid matrix . However, information about biodegradation in complex matrices is largely limited to studies of closed systems under batch conditions in which potential bioavailability is characterised by the aqueous-phase concentration of a contaminant . There is little knowledge regarding the influence of flow-through conditions on the availability of contaminants to microbes (contaminant bioavailability) . Thus, the aim of this study was to assess and compare contaminant bioavailability, in the presence of a sorptive medium, under both batch and flow-through conditions . Accordingly, experiments were designed in which pentachlorophenol (PCP) was introduced into a mixture of inoculated silica sand and a PCP-retaining resin, under either batch or flow-through (columns) conditions . The results indicated that an increase in the amount of resin (0.1-0.2 g) clearly lowered PCP availability to microbes after 170 h under batch conditions (30 and 45% respectively); whereas, the initial decrease in bioavailability observed under flow-through conditions (45 and 70% respectively) was reversed and no longer observable after 170 h . This increase in PCP availability was linked to an improvement in the contaminant biodegradation capacity from 0.03 to 0.13 mg x l(-1) x h(-1) over 200 h.

Appl Microbiol Biotechnol, 2004 Apr, 64(3), 317 - 25 Epub 2004 Jan 10.
Microbial P450 enzymes in biotechnology; Urlacher VB et al.; Oxidations are key reactions in chemical syntheses . Biooxidations using fermentation processes have already conquered some niches in industrial oxidation processes since they allow the introduction of oxygen into non-activated carbon atoms in a sterically and optically selective manner that is difficult or impossible to achieve by synthetic organic chemistry . Biooxidation using isolated enzymes is limited to oxidases and dehydrogenases . Surprisingly, cytochrome P450 monooxygenases have scarcely been studied for use in biooxidations, although they are one of the largest known superfamilies of enzyme proteins . Their gene sequences have been identified in various organisms such as humans, bacteria, algae, fungi, and plants . The reactions catalyzed by P450s are quite diverse and range from biosynthetic pathways (e.g . those of animal hormones and secondary plant metabolites) to the activation or biodegradation of hydrophobic xenobiotic compounds (e.g . those of various drugs in the liver of higher animals) . From a practical point of view, the great potential of P450s is limited by their functional complexity, low activity, and limited stability . In addition, P450-catalyzed reactions require a constant supply of NAD(P)H which makes continuous cell-free processes very expensive . Quite recently, several groups have started to investigate cost-efficient ways that could allow the continuous supply of electrons to the heme iron . These include, for example, the use of electron mediators, direct electron supply from electrodes, and enzymatic approaches . In addition, methods of protein design and directed evolution have been applied in an attempt to enhance the activity of the enzymes and improve their selectivity . The promising application of bacterial P450s as catalyzing agents in biocatalytic reactions and recent progress made in this field are both covered in this review.

J Pharm Pharmacol, 2003 Nov, 55(11), 1451 - 63
The potential of chitosan in ocular drug delivery; Alonso MJ et al.; This paper presents an overview of the potential of chitosan-based systems for improving the retention and biodistribution of drugs applied topically onto the eye . Besides its low toxicity and good ocular tolerance, chitosan exhibits favourable biological behaviour, such as bioadhesion- and permeability-enhancing properties, and also interesting physico-chemical characteristics, which make it a unique material for the design of ocular drug delivery vehicles . The review summarizes the techniques for the production of chitosan gels, chitosan-coated colloidal systems and chitosan nanoparticles, and describes their mechanism of action upon contact with the ocular mucosa . The results reported until now have provided evidence of the potential of chitosan gels for enhancing and prolonging the retention of drugs on the eye surface . On the other hand, chitosan-based colloidal systems were found to work as transmucosal drug carriers, either facilitating the transport of drugs to the inner eye (chitosan-coated colloidal systems containing indometacin) or their accumulation into the corneal/conjunctival epithelia (chitosan nanoparticles containing ciclosporin) . Finally, the tolerance, toxicity and biodegradation of the carriers under evaluation were reviewed.

Appl Environ Microbiol, 2004 Jan, 70(1), 508 - 17
Biodegradation of nitro-substituted explosives 2,4,6-trinitrotoluene, hexahydro-1,3,5-trinitro-1,3,5-triazine, and octahydro-1,3,5,7-tetranitro-1,3,5-tetrazocine by a phytosymbiotic Methylobacterium sp . associated with poplar tissues (Populus deltoides x nigra DN34); Van Aken B et al.; A pink-pigmented symbiotic bacterium was isolated from hybrid poplar tissues (Populus deltoides x nigra DN34) . The bacterium was identified by 16S and 16S-23S intergenic spacer ribosomal DNA analysis as a Methylobacterium sp . (strain BJ001) . The isolated bacterium was able to use methanol as the sole source of carbon and energy, which is a specific attribute of the genus Methylobacterium . The bacterium in pure culture was shown to degrade the toxic explosives 2,4,6-trinitrotoluene (TNT), hexahydro-1,3,5-trinitro-1,3,5-triazene (RDX), and octahydro-1,3,5,7-tetranitro-1,3,5-tetrazocine (HMX) . {U-ring-(14)C}TNT (25 mg liter(-1)) was fully transformed in less than 10 days . Metabolites included the reduction derivatives amino-dinitrotoluenes and diamino-nitrotoluenes . No significant release of (14)CO(2) was recorded from {(14)C}TNT . In addition, the isolated methylotroph was shown to transform {U-(14)C}RDX (20 mg liter(-1)) and {U-(14)C}HMX (2.5 mg liter(-1)) in less than 40 days . After 55 days of incubation, 58.0% of initial {(14)C}RDX and 61.4% of initial {(14)C}HMX were mineralized into (14)CO(2) . The radioactivity remaining in solution accounted for 12.8 and 12.7% of initial {(14)C}RDX and {(14)C}HMX, respectively . Metabolites detected from RDX transformation included a mononitroso RDX derivative and a polar compound tentatively identified as methylenedinitramine . Since members of the genus Methylobacterium are distributed in a wide diversity of natural environments and are very often associated with plants, Methylobacterium sp . strain BJ001 may be involved in natural attenuation or in situ biodegradation (including phytoremediation) of explosive-contaminated sites.

Appl Environ Microbiol, 2004 Jan, 70(1), 324 - 31
Differential stress-induced regulation of two quinone reductases in the brown rot basidiomycete Gloeophyllum trabeum; Cohen R et al.; Quinone reductases (QRDs) have two important functions in the basidiomycete Gloeophyllum trabeum, which causes brown rot of wood . First, a QRD is required to generate biodegradative hydroxyl radicals via redox cycling between two G . trabeum extracellular metabolites, 2,5-dimethoxyhydroquinone (2,5-DMHQ) and 2,5-dimethoxy-1,4-benzoquinone (2,5-DMBQ) . Second, because 2,5-DMBQ is cytotoxic and 2,5-DMHQ is not, a QRD is needed to maintain the intracellular pool of these metabolites in the reduced form . Given their importance in G . trabeum metabolism, QRDs could prove useful targets for new wood preservatives . We have identified two G . trabeum genes, each existing in two closely related, perhaps allelic variants, that encode QRDs in the flavodoxin family . Past work with QRD1 and heterologous expression of QRD2 in this study confirmed that both genes encode NADH-dependent, flavin-containing QRDs . Real-time reverse transcription PCR analyses of liquid- and wood-grown cultures showed that qrd1 expression was maximal during secondary metabolism, coincided with the production of 2,5-DMBQ, and was moderately up-regulated by chemical stressors such as quinones . By contrast, qrd2 expression was maximal during fungal growth when 2,5-DMBQ levels were low, yet was markedly up-regulated by chemical stress or heat shock . The total QRD activity in lysates of G . trabeum mycelium was significantly enhanced by induction beforehand with a cytotoxic quinone . The promoter of qrd2 contains likely antioxidant, xenobiotic, and heat shock elements, absent in qrd1, that probably explain the greater response of qrd2 transcription to stress . We conclude from these results that QRD1 is the enzyme G . trabeum routinely uses to detoxify quinones during incipient wood decay and that it could also drive the biodegradative quinone redox cycle . However, QRD2 assumes a more important role when the mycelium is stressed.

Microb Ecol, 2003 Aug, 46(2), 145 - 60 Epub 2003 Jul 04.
Microbial community responses to atrazine exposure and nutrient availability: linking degradation capacity to community structure; Rhine ED et al.; Repeated pesticide exposure may enhance biodegradation through selective enrichment of pesticide-metabolizing microorganisms, particularly when the compound is used as a C and energy source . The relationship between pesticide application history and degradation rate is unclear when the chemical is utilized as a nutrient source other than C . Atrazine, a poor source of C and energy, was chosen as a model compound because it can serve as an N source for some microorganisms . Soils with (H-soil) and without (NH-soil) prior s-triazine treatment history were repeatedly exposed to atrazine and a variety of C and N source amendments . Exposure to atrazine and inorganic-N availability were the dominant factors leading to the development of microbial communities with an enhanced capacity to degrade atrazine . The density of the atrazine-degrading microorganisms increased immediately, up to 1000-fold, with atrazine exposure in the H-soil, but comparable increases were not observed in the NH-soil until 12 weeks following laboratory acclimation, despite high rates of atrazine mineralization in these soils immediately following the acclimation period . Whole-soil fatty acid methyl ester (FAME) analysis showed that the application of alternative C and N sources in addition to atrazine resulted in a microbial community composition that was distinctly different from that in either the atrazinealone treatment or water controls for both the H- and NH-soils . These data suggest that the microbial communities in both soils were altered differently in response to the treatments but developed a similar enhanced capacity to mineralize atrazine.

Ann Chim, 2003 Nov, 93(11), 889 - 96
Fungal colonization on stoneworks . Interaction fungi-powdered stone samples; Sbaraglia G et al.; The microbial activity plays an important role in the biodegradative processes implied in stonework decay . In natural environments it is not possible to separate the damage produced by microorganisms from damage caused by physical and chemical agents . In vitro assays carried out with microbes isolated from weathered stones are required in order to understand the biological mechanisms involved in stone deterioration . We have described, as commented in the text, how fungal colonization observed on scaglia may be the result of the fine grain size of rock, whereas inhibition of growth on marble may depend on the surface characteristics of calcite grains after grinding . The extent of microbial growth clearly depends on the quantity of cations released in solution . However, fungal growth may, in turn, induce a decrease in pH, thus promoting mineral chemical attack . These observation points to selective action of fungal species in promoting weathering well evidenced by the presence of different extents of cations released in suspension from the same sample . Detailed studies are in progress in order to go into this question.

Water Sci Technol, 2003, 48(9), 103 - 11
Low temperature biodegradation of airport de-icing fluids; Revitt DM et al.; The biodegradabilities of glycol- and acetate-based aircraft de-icing fluids on airport surfaces have been investigated at three temperatures between 0 degrees C and 10 degrees C . The aqueous solubilities of these substances can result in high BOD loadings in runoff and pose serious toxicity problems in receiving waters . The measured surface biodegradation rates for de-icing products based on ethylene/diethylene glycol (Konsin), propylene glycol (Kilfrost) and potassium acetate (Clearway) at 4 degrees C were 0.082, 0.073 and 0.033 day(-1) . The resulting reductions in the potential BOD loadings, of a single application of a typical mixture of these products, over a 5 day biodegradation period are predicted to be 32.9%, 30.2% and 21.4%, respectively at 8 degrees C, 4 degrees C and 1 degrees C . For consecutive daily applications, the comparable cumulative reductions over 5 days are 20.8%, 18.9% and 13.3% . The subsequent savings in the amount of treatment required for airport runoff prior to safe discharge to receiving waters are discussed and hence the relevance of surface biodegradation processes to the design of stormwater treatment systems involving the wash-off of biodegradable pollutants following retention on urban surfaces.

J Dent Res, 2004 Jan, 83(1), 22 - 6
Salivary esterase activity and its association with the biodegradation of dental composites; Finer Y et al.; Pseudocholinesterase (PCE) and cholesterol esterase (CE) can hydrolyze bisphenylglycidyl dimethacrylate (bisGMA) and triethylene glycol dimethacrylate (TEGDMA) monomers . This study will test the hypothesis that enzyme activities showing CE and PCE character are found in human saliva at levels sufficient to hydrolyze ester-containing composites important to restorative denstistry . The study also seeks to ask if the active sites of CE and PCE with respect to composite could be inhibited . Photo-polymerized model composite resin was incubated in PCE and CE solutions, in the presence and absence of a specific esterase inhibitor, phenylmethylsulfonyl fluoride (PMSF) . Incubation solutions were analyzed for resin degradation products by high-performance liquid chromatography (HPLC), UV spectroscopy, and mass spectrometry . Saliva was found to contain both hydrolase activities at levels that could degrade composite resins . PMSF inhibited the composite degradation, indicating a material hydrolysis mechanism similar to the enzymes' common function.

Environ Sci Pollut Res Int, 2003, 10(6), 379 - 84
Practical applications of the Fenton reaction to the removal of chlorinated aromatic pollutants . Oxidative degradation of 2,4-dichlorophenol; Detomaso A et al.; BACKGROUND: Chlorophenols (CPs) constitute a group of organic pollutants that are introduced into the environment as a result of several man-made activities, such as uncontrolled use of pesticides and herbicides, and as byproducts in the paper pulp bleaching . Promising removal technologies of chlorinated aromatics consist in the application of advanced oxidation processes (AOPs) that can provide an almost total degradation of a variety of contaminants . Among these, wide application find Fenton systems based on generation of reactive species having a high oxidizing power, such as hydroxyl radical HO* . Our objective was that of determining the overall degradation efficiency of the model compound 2,4-dichlorophenol (DCP) by thermal Fenton-type oxidation systems with a view toward defining in more details relevant process parameters, the effect of reaction temperature and of co-catalyst Cu2+ . METHODS: Reaction conditions were similar to those generally adopted as optimal in many practical applications, i.e . pollutant/Fe2+ (as FeSO4) ratio ca . 20, Fe2+/Cu2+ (co-catalyst) 2:1, pH adjusted and controlled at pH 3, and H2O2 in excess (up to four-fold over the stoichiometric amount required for complete mineralization) . RESULTS AND DISCUSSION: The results demonstrate that it is advantageous to carry out the reaction at a temperature markedly higher (70 degrees C) than ambient . The stepwise addition of H2O2 in aliquots yields an efficient transformation, while allowing a convenient control of the reaction exothermicity . Under these conditions, the essentially complete removal of the initial DCP is accomplished using just one equiv of H2O2 during 15 min; excess H2O2 (5 equivalents) yields extensive substrate mineralization . Also relevant, at 70 degrees C dechlorination of the initial DCP (and of derived reaction intermediates) is remarkably extensive (3-5% residual TOX), already with the addition of 1 equiv of H2O2 . At the end of the reaction, IC and IC-MS analyses of the solution reveal that only low-molecular weight carboxylic acid (acetic, formic, oxalic, malonic, tartaric, etc.) contribute to the residual TOC . CONCLUSIONS: The whole of the results herein point to the advantage of performing the process at temperatures substantially higher than ambient (70 degrees C) . Under the conditions adopted, almost complete degradation of the initial toxic compound can be achieved using hydrogen peroxide in fair excess (e.g., 3.5 equiv H2O2) . RECOMMENDATIONS AND OUTLOOK: In applying practical Fenton-type degradation systems to heavily polluted wastes, either for the pre-treatment of waters with a high COD value prior to biodegradation or for complete mineralization of pollutants, the set up of appropriate reaction conditions appears to be a key factor . Also, it is desirable to keep the concentration of iron salts within the lower limits in order to minimize the production and disposal of iron oxide sludges.

Water Sci Technol, 2003, 48(8), 177 - 83
Biodegradation of polycyclic aromatic hydrocarbons (PAHs) by microbial consortia enriched from mangrove sediments; Tam NF et al.; Surface sediments from two mangrove swamps in Hong Kong were enriched to obtain PAH-degrading microbial consortia . The consortium from sediments enriched with phenanthrene (Phe) in Ma Wan, a mangrove swamp next to a boat anchorage, was effective in degrading PAH with 96.7% and 89.9% Phe degradation at 0 and 10 ppt salinities, respectively . The Phe-enriched microbial consortium could also use pyrene (Pyr) as the sole carbon source but the degradation was much less (around 15%) . On the other hand, the Phe-enriched consortium from sediments in Yi O, a mangrove swamp recently polluted by an oil spill, completely removed Phe and Pyr at both 0 and 10 ppt salinities . This suggests that different consortia were selected in two sediments using the same PAH substrate . Not only sediments, PAH substrate used for enrichment also selected different consortia . The Pyr- and Fla-enriched Yi O consortia only achieved 10.5 and 4.5% Phe degradation, respectively and the corresponding pyrene degradation was 7 and 40% . Among the three PAH compounds, fluoranthene (Fla) was most difficult to degrade, and 21.1, 11.3, and 36.8% Fla were degraded by Phe-, Fla- and Pyr-enriched cultures, respectively.

Arh Hig Rada Toksikol, 2003 Sep, 54(3), 189 - 95
Comparison of diethylene glycol and phenol biodegradability by different test methods; Zgajnar Gotvajn A et al.; Biodegradation is generally recognised as an important removal mechanism for pollutants in natural ecosystems . It determines the concentration of substances in the environment . According to the legislation of the European Union, there are three levels for biodegradability testing protocols for chemicals which cover different test conditions . This paper describes one such multilevel approach to biodegradation testing . Four different tests were performed on diethylene glycol and phenol . Diethylene glycol did not fulfill the requirements for ready biodegradable substances, while it degraded well in wastewater treatment plant simulation test . Phenol in turn, resulted ready biodegradable, and its biodegradability depended less on experimental conditions than the biodegradability of diethylene glycol . This corroborates the importance of combining different test methods to obtain relevant biodegradability data.

Water Res, 2004 Jan, 38(2), 375 - 84
4-nitrophenol biodegradation in a sequencing batch reactor: kinetic study and effect of filling time; Tomei MC et al.; Biodegradation kinetics of 4-nitrophenol (4NP) was investigated in a lab-scale sequencing batch reactor fed with the compound as the sole carbon source . The experimental results showed that complete 4NP removal can be easily achieved with acclimatized biomass, even if an inhibition kinetics is observed; furthermore, an improvement in the removal kinetics is obtained if the substrate concentration peak, reached in the reactor at the end of the filling time, is maintained to quite a low value . Both long feed phase and high biomass concentration are effective in reducing the substrate concentration peak and then improving the process efficiency . Kinetic test data are well correlated by the Haldane equation, with a saturation constant Ks and an inhibition constant KI, of 17.6 and 30.7 (mg l(-1) 4NP), respectively, whereas the maximum removal rate was in the range of 3.3-8.4 (mg 4NP mg VSS(-1) d(-1)) depending on the substrate concentration peak reached in the reaction phase.

J Environ Qual, 2003 Nov-Dec, 32(6), 2207 - 15
Modeling of sorption and biodegradation of parathion and its metabolite paraoxon in soil; Saffih-Hdadi K et al.; To investigate the distribution of parathion {O,O-diethyl O-(4-nitrophenyl) phosphorothioate} and its highly toxic metabolite paraoxon {O,O-diethyl O-(4-nitrophenyl)phosphate} between the soluble and sorbed pools in the soil, batch experiments were conducted to evaluate the rate of adsorption and desorption of 14C-labeled parathion and paraoxon in soil . The mineralization and degradation of these products were also investigated during a 56-d experiment under controlled laboratory conditions . Adsorption patterns indicated initial fast adsorption reactions occurring within 4 h for both parathion and paraoxon . We also observed the formation of nonextractable residues . The paraoxon was more intensively degraded than the parathion, and production of p-nitrophenol and other metabolites was observed . A kinetic model was developed to describe the sorption and biodegradation rates of parathion, taking into account the production, retention, and biodegradation of paraoxon, the main metabolite of parathion . After fitting the parameters of the model we made a simulation of the kinetics of the appearance and disappearance of paraoxon . From the simulation we predicted a quantity of metabolite in the liquid phase amounting to 1% of the quantity of parathion initially applied . This is in agreement with the experimental data.

J Environ Sci Health A Tox Hazard Subst Environ Eng, 2003, 38(12), 2857 - 65
Variation of microcystins in a lake for water supply; Zhang WH et al.; A site investigation was conducted to correlate the relationships between microcystins (MC) concentration and algal growth in Dianchi Lake in China . Laboratory experiments were undertaken to test the effects of sediment adsorption, photoirradiation and biodegradation on microcystins removal . Bioaccumulation of microcystins was also determined using silver carp fish . It was observed that MC concentrations varied in accordance with algae growth in Dianchi Lake . The results obtained in the laboratory demonstrated that the removal of MC with fresh sediments was less than 10%, photoirradiation removed more than 75% MC within two hours, and the biodegradation needed much longer time to produce substantial degradation of MC . The results suggest that bioaccumulation of microcystins in fish was not significant in Dianchi Lake.

Cancer Lett, 2004 Jan 8, 203(1), 59 - 69
Cytostatic and cytotoxic activity of synthetic genistein glycosides against human cancer cell lines; Polkowski K et al.; Genistein, the principal soy isoflavone, is a molecule of great interest as an innovative chemotherapeutic agent or as a lead-compound in anticancer drug design . To enhance intrinsic activity of genistein and to explore its pharmacophoric potential, its glycosidic derivatives were synthesized . On the basis of structural features and calculated lipophilicity coefficient (ClogP) the derivatives were classified as hydrophilic (i.e . those containing free sugar moiety) or lipophilic (i.e . those with alkylated or acylated sugar hydroxyls) . The in vitro cytostatic and cytotoxic studies showed hydrophilic glycosides to be practically inactive against human cancer cell lines when compared to the free aglycone . On the contrary, lipophilic glycosides were significantly more active than the parent isoflavone although the correlation between ClogP and the activity was not clear . On the basis of GI50 and LC50 values two of the most active glycosides were found to be several times more potent in their cytostatic and cytotoxic effect than genistein . Additionally all lipophilic glycosides were revealed to exhibit different mode of action in comparison to genistein . It may suggest that these compounds do not undergo rapid biodegradation, either in culture media or inside cells, and exert their biological effects primarily as intact molecules.

Biodegradation, 2003 Dec, 14(6), 373 - 84
Effects of heterogeneity and experimental scale on the biodegradation of diesel; Davis C et al.; Biodegradation of petroleum hydrocarbon contamination is a common method for remediating soils and groundwater . Due to complexities with field-scale studies, biodegradation rates are typically evaluated at the bench-scale in laboratory studies . However, important field conditions can be difficult to mimic in the laboratory . This study investigates three scaling factors that can impact laboratory biodegradation rates and that are frequently unaccounted for in typical laboratory experimental procedures . These factors are soil heterogeneity, morphology of petroleum hydrocarbon non-aqueous phase liquids (NAPLs) and soil moisture distribution . The effects of these factors on the biodegradation rate of diesel NAPL is tested under a variety of experimental procedures from well-mixed batch studies to four-foot static soil columns . The results indicate that a high degree of variability results from even small-scale heterogeneities . In addition, it appears that as the experimental scale increases, the measured biodegradation rates slow . The results indicate that diesel biodegradation rates derived from small-scale experiments are not necessarily representative of field-scale biodegradation rates.

Pest Manag Sci, 2003 Dec, 59(12), 1291 - 302
The ability of indigenous micro-organisms to degrade isoproturon, atrazine and mecoprop within aerobic UK aquifer systems; Johnson AC et al.; The potential for the herbicides isoproturon, atrazine and mecoprop to degrade in the major UK aquifers of chalk, sandstone and limestone was studied using laboratory microcosms spiked at 100 microg litre(-1) . Significant mecoprop degradation was only observed in sandstone groundwater samples . Atrazine transformation, based on the formation of metabolites, did occur in most groundwater samples, but only at a rate of 1-3% per year . A potential to degrade isoproturon was observed in groundwater samples from each of the aquifer types, with the most rapid and consistent degradation occurring at the sandstone field site . Biodegradation was confirmed by the formation of monodesmethyl- and didesmethyl-isoproturon . Isoproturon degradation potential rates obtained from the groundwater microcosms could not be correlated with either dissolved organic carbon or numbers of bacteria in the groundwater . It was noted that the ability of the groundwater at a field site to degrade a pesticide was not related to performance of the soil above.

Appl Biochem Biotechnol, 2003 Dec, 111(3), 167 - 84
Novel laccase redox mediators: spectral, electrochemical, and kinetic properties; Shleev SV et al.; The screening of potential redox mediators for laccase was performed using homogeneous enzyme preparations from Coriolus hirsutus and Coriolus zonatus . It was discovered that derivatives of 1-phenyl-3-methyl-pyrazolones were efficient substrates for the laccases . The characterization of two representatives of the 1-phenyl-pyrazolone class, sodium 1-phenyl-3-methyl-4- methylamino-pyrazolone-5-N(4)-methanesulfonate and 1-(3'-sulfophenyl)-3- methylpyrazolone-5, in the reaction catalyzed by laccase was carried out using spectral, electrochemical, and enzyme kinetics methods . The kinetic parameters for the oxidation of the newly discovered substrates were comparable with those for 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonate) (ABTS) oxidation by laccase . Electrochemical experiments demonstrated that oxidation of these compounds yielded two high-potential intermediates capable of oxidizing veratryl alcohol, which was used as a lignin model substrate, to the corresponding aldehyde and acid . 1-(3'-Sulfophenyl)-3- methylpyrazolone-5 was about 30-40% as effective in degrading veratryl alcohol compared to ABTS as judged from high-performance liquid chromatography kinetic studies . 1-Phenyl-3-methyl-pyrazolones may be of commercial interest for oxidoreductase-catalyzed biodegradation of organic compounds.

Environ Int, 2004 Mar, 30(1), 7 - 10
Polychlorinated biphenyl levels in adipose tissue of primiparous women in Turkey; Cok I et al.; Polychlorinated biphenyls (PCBs) are a mixture of 209 possible congeners with different chlorine substitutions and they are potentially hazardous compounds in the environment for human beings . The high lipophilicity and the resistance to biodegradation of PCBs allow the bioaccumulation of these chemicals in the fatty tissues of organisms . The objective of this study was to determine the levels of PCBs in the adipose tissue of women living in Ankara, Turkey . For this purpose, levels of seven major persistent PCB congeners (IUPAC Numbers: 28, 52, 101, 118, 138, 153, 180) were measured in 29 primiparous mothers' adipose tissue samples by gas chromatography with electron capture detection (GC-ECD) . PCB IUPAC numbers 138, 153 and 180 were the most abundant congeners, each accounting for > 20% of the total PCB content of adipose tissue . PCB 153 was the dominant congener in all the samples (141.7 +/- 132.3 ng/g lipid wt . basis) . The results are compared with the similar studies from other countries . The concentrations of PCB 28, PCB 52 and PCB 101 were found to be higher than those found in industrialized countries . This study is important in terms of being the first study of determination of PCB levels in adipose tissue samples in Turkey.

J Agric Food Chem, 2003 Dec 17, 51(26), 7725 - 9
Bioconcentration and elimination of sulfamethazine and its main metabolite in sturgeon (Acipenser schrenkii); Hou X et al.; A steady-state bioconcentration and elimination of sulfamethazine (SM(2)) in the sturgeon (A . schrenkii) was conducted in flow-through aqueous conditions . Two treated groups of fish were exposed to concentrations of 1.00 and 0.10 mg/L of SM(2), respectively . SM(2) and its main metabolite, N(4)-acetyl-SM(2), were determined in both fish muscle and water during the 8-day uptake period and the subsequent 6-day elimination period . Rapid uptakes of the drug were observed in both treated groups . Muscle tissue residues plateaued after approximately 3 days . The bioconcentration factor in muscle (BCF(m)) in the low-concentration drug solution was 1.19 and that in the high-concentration-treated level was 0.61 . The calculated biodegradation index was 3.72% . The elimination half-times (t(1/2)) of the two treatment levels were 19.44 and 23.52 h, respectively . The result indicates that SM(2) will neither bioconcentrate in individual aquatic organisms nor biomagnify in the food chain, although the BCF(m) was relatively higher under the low-concentration exposure.

J Chromatogr A, 2003 Dec 5, 1020(1), 131 - 51
Determination of fluorinated surfactants and their metabolites in sewage sludge samples by liquid chromatography with mass spectrometry and tandem mass spectrometry after pressurised liquid extraction and separation on fluorine-modified reversed-phase sorbents; Schroder HF; An analytical method was elaborated for simultaneous extraction and determination of fluorinated anionic and non-ionic surfactants in sewage sludge . Surfactant compounds were determined by liquid chromatography-mass spectrometry (LC-MS) after Soxhlet extraction, hot steam extraction and pressurised liquid extraction (PLE) using spiked sludge samples . PLE in a multiple-step procedure consisting of sequential use of ethyl acetate-dimethylformamide and methanol-phosphoric acid resulted in the most efficient extraction procedure . Quantitative analyses of the fluorinated anionic perfluorooctanesulfonate (PFOS) and the partly fluorinated non-ionic alkylpolyglycol ether (FAEO) surfactants were performed by selected ion monitoring LC-MS . Electrospray ionisation or atmospheric pressure chemical ionisation in negative or positive mode was performed . Recoveries between 105 and 120% could be reached . No PFOS and non-ionic FAEO surfactants in concentrations higher than 6 or 10 mg kg(-1) dry matter were observed in real environmental samples . Therefore aerobic and anaerobic biodegradation was performed to investigate the fate of fluorinated surfactants reaching wastewaters . Biological wastewater treatment in laboratory scale under aerobic or anaerobic conditions led to an elimination by biodegradation.

J Biomed Mater Res A, 2004 Jan 1, 68(1), 79 - 89
Novel bioactive and biodegradable glass ceramics with high mechanical strength in the CaO--SiO2--B2O3 system; Ryu HS et al.; Novel bioactive and biodegradable glass ceramics with high mechanical strength in the (50-x/2)CaO . SiO(2)--xB(2)O(3) (4.2 < or = x < or = 17.2) system were investigated . The systems consisted of three phases: monoclinic wollastonite, calcium metaborate, and amorphous borosilicate matrix . The glass ceramics containing 4.2 mol% and 8.4 mol% B(2)O(3) showed high bulk density and a dense microstructure . Mechanical strengths of the glass ceramics were higher than those of other bioactive ceramics: high compressive strength (2813 MPa), bending strength of 212 MPa, and fracture toughness of 3.12 MPa . m(1/2) . The glass-ceramic formed apatite layer on their surface in the simulated body fluid and showed significant biodegradation . The degree of apatite formation in the glass ceramics depended on the calcium metaborate content and borosilicate glassy matrix . Additional calcium metaborate and borosilicate glassy matrix increased the apatite formation rate on the surface . It might be likely that calcium metaborate causes supersaturation of Ca ions, for its high solubility in SBF and the water-reactive borosilicate glassy matrix formed Sibond;OH groups on the surface to provide nucleation sites for apatite formation . Also, through in vitro test for the biocompatibility of the CaO--SiO(2)--B(2)O(3) glass ceramics, no cytotoxicity of the glass ceramics were found . The results on bioactivity and noncytotoxicity indicated that glass ceramics in the (50-x/2)CaO . SiO(2)--xB(2)O(3) (4.2 < or = x < or = 17.2) system could be useful as a biodegradable bone replacement material .

Appl Environ Microbiol, 2003 Dec, 69(12), 7385 - 94
Cometabolism of methyl tertiary butyl ether and gaseous n-alkanes by Pseudomonas mendocina KR-1 grown on C5 to C8 n-alkanes; Smith CA et al.; Pseudomonas mendocina KR-1 grew well on toluene, n-alkanes (C5 to C8), and 1 degrees alcohols (C2 to C8) but not on other aromatics, gaseous n-alkanes (C1 to C4), isoalkanes (C4 to C6), 2 degrees alcohols (C3 to C8), methyl tertiary butyl ether (MTBE), or tertiary butyl alcohol (TBA) . Cells grown under carbon-limited conditions on n-alkanes in the presence of MTBE (42 micromoles) oxidized up to 94% of the added MTBE to TBA . Less than 3% of the added MTBE was oxidized to TBA when cells were grown on either 1 degrees alcohols, toluene, or dextrose in the presence of MTBE . Concentrated n-pentane-grown cells oxidized MTBE to TBA without a lag phase and without generating tertiary butyl formate (TBF) as an intermediate . Neither TBF nor TBA was consumed by n-pentane-grown cells, while formaldehyde, the expected C1 product of MTBE dealkylation, was rapidly consumed . Similar Ks values for MTBE were observed for cells grown on C5 to C8 n-alkanes (12.95 +/- 2.04 mM), suggesting that the same enzyme oxidizes MTBE in cells grown on each n-alkane . All growth-supporting n-alkanes (C5 to C8) inhibited MTBE oxidation by resting n-pentane-grown cells . Propane (Ki = 53 micromoles) and n-butane (Ki = 16 micromoles) also inhibited MTBE oxidation, and both gases were also consumed by cells during growth on n-pentane . Cultures grown on C5 to C8 n-alkanes also exhibited up to twofold-higher levels of growth in the presence of propane or n-butane, whereas no growth stimulation was observed with methane, ethane, MTBE, TBA, or formaldehyde . The results are discussed in terms of their impacts on our understanding of MTBE biodegradation and cometabolism.

Appl Environ Microbiol, 2003 Dec, 69(12), 6987 - 93
Nitrogen control of atrazine utilization in Pseudomonas sp . strain ADP; Garcia-Gonzalez V et al.; Pseudomonas sp . strain ADP uses the herbicide atrazine as the sole nitrogen source . We have devised a simple atrazine degradation assay to determine the effect of other nitrogen sources on the atrazine degradation pathway . The atrazine degradation rate was greatly decreased in cells grown on nitrogen sources that support rapid growth of Pseudomonas sp . strain ADP compared to cells cultivated on growth-limiting nitrogen sources . The presence of atrazine in addition to the nitrogen sources did not stimulate degradation . High degradation rates obtained in the presence of ammonium plus the glutamine synthetase inhibitor MSX and also with an Nas(-) mutant derivative grown on nitrate suggest that nitrogen regulation operates by sensing intracellular levels of some key nitrogen-containing metabolite . Nitrate amendment in soil microcosms resulted in decreased atrazine mineralization by the wild-type strain but not by the Nas(-) mutant . This suggests that, although nitrogen repression of the atrazine catabolic pathway may have a strong impact on atrazine biodegradation in nitrogen-fertilized soils, the use of selected mutant variants may contribute to overcoming this limitation.

Appl Spectrosc, 2003 May, 57(5), 514 - 7
Monitoring decay of black gum wood (Nyssa sylvatica) during growth of the shiitake mushroom (Lentinula edodes) using diffuse reflectance infrared spectroscopy; Vane CH; Abstract diffuse reflectance infrared spectroscopy (DRIFT) and elemental analysis were employed to monitor biodegradation of black gum wood (Nyssa sylvatica) during growth of the shiitake mushroom (Lentinula edodes) . Black gum was decayed for up to 4.3 years by L . edodes, during which time it was sampled at 19, 31, and 52 months . Biodegraded woods displayed increased % O (w/w) and decreased % C (w/w) relative to the undecayed control . The DRIFT spectra of decayed black gum showed a decrease in relative intensity of absorption bands at 1735 cm(-1) assigned to carboxyl functional groups from xylans and an increase in the absorption band at 1640 cm(-1) assigned to conjugated carbonyl groups originating from lignin . Xylan decay was rapid initially but slowed after 19 months; however, oxidative decay of the lignin side chains occurred throughout the 52-month decay period . Overall elemental and DRIFT data show that both polysaccharides and lignin were decayed during cultivation of the edible white-rot fungus.

Appl Spectrosc, 2003 Jul, 57(7), 835 - 41
FT-IR spectroscopic analysis of rainbow trout liver exposed to nonylphenol; Cakmak G et al.; Nonylphenol (NP) is a biodegradation product of nonylphenol ethoxylates (NPEs) belonging to the alkylphenol ethoxylates (APEs) group . APEs are widely used nonionic surfactants in detergents, herbicides, pesticides, paints, and cosmetics . The present work investigates the effects of NP on rainbow trout (Oncorhynchus mykiss) livers at the molecular level using Fourier transform infrared (FT-IR) spectroscopy . The FT-IR spectra revealed dramatic differences between the NP-treated and control tissues, which mainly indicated that the level of triglycerides increased, the lipid order increased, and the protein concentration decreased in the treated samples . Moreover, it was also found that glycogen levels significantly decreased and the relative content of nucleic acids increased in NP-treated fish . The 17beta-Estradiol-treated fish liver spectra were found to be quite similar to those of NP-treated fish . All these results implied that rainbow trout may offer considerable promise to be used as a bioindicator for NP in the future.

Appl Microbiol Biotechnol, 2004 Mar, 64(1), 53 - 61 Epub 2003 Dec 05.
Estimation of contaminant depletion in unsaturated soils using a reduced-order biodegradation model and carbon dioxide measurement; Schoefs O et al.; The objective of this study was to develop a reduced-order model of biodegradation in unsaturated soils that allows the estimation of contaminant depletion, using available on-line measurements . Hexadecane was chosen as a model compound for petroleum hydrocarbons . A two-compartment model was developed, decoupling the intrinsic biodegradation kinetics from limiting factors imposed by field conditions, such as oxygen transfer and contaminant bioavailability . Two new experimental protocols (one for the liquid phase and the other for the solid phase) were developed to monitor hexadecane depletion, hexadecane mineralization, total mineralization, and evolution of the degraders . Using the liquid-phase experiment, parameters of a Haldane kinetic model and yield coefficients were identified and used in the complete model of biodegradation in soil . Using the carbon dioxide production curve, a biocontact kinetic model was identified so that, despite the high sensitivity of the model outputs to variations in the parameters, hexadecane depletion could be correctly predicted with an average error on the entire time trajectory of about 8% . Moreover, the ratio between hexadecane mineralization and total mineralization remained constant after a brief transient period, indicating that hexadecane mineralization could be deduced from the total carbon dioxide measurement . Finally, the new model developed in this study allows real-time monitoring of contaminant biodegradation, using on-line carbon dioxide measurement.

Environ Sci Technol, 2003 Nov 15, 37(22), 5213 - 8
Anaerobic oxidation of crude oil hydrocarbons by the resident microorganisms of a contaminated anoxic aquifer; Townsend GT et al.; The biodegradation of two crude oils by microorganisms from an anoxic aquifer previously contaminated by natural gas condensate was examined under methanogenic and sulfate-reducing conditions . Artificially weathered Alaska North Slope crude oil greatly stimulated both methanogenesis and sulfate reduction . Gas chromatographic analysis revealed the entire n-alkane fraction of this oil (C13-C34) was consumed under both conditions . Naphthalene, 2-methylnaphthalene, and 2-ethylnaphthalene were also biodegraded but only in the presence of sulfate . Alba crude oil, which is naturally depleted in n-alkanes, resulted in a relatively modest stimulation of methanogenesis and sulfate reduction . Polycyclic aromatic hydrocarbon biodegradation was similar to that found for the Alaska North Slope crude oil, but a broader range of compounds was metabolized, including 2,6-dimethylnaphthalene and 2,7-dimethylnaphthalene in the presence of sulfate . These results indicate that n-alkanes are relatively labile, and their biodegradation in terrestrial environments is not necessarily limited by electron acceptor availability . Polycyclic aromatic hydrocarbons are relatively more recalcitrant, and the biodegradation of these substrates appeared to be sulfate-dependent and homologue-specific . This information should be useful for assessing the limits of in situ crude oil biodegradation in terrestrial environments and for making decisions regarding risk-based corrective actions.

Environ Sci Technol, 2003 Nov 15, 37(22), 5168 - 74
"Humic coverage index" as a determining factor governing strain-specific hydrocarbon availability to contaminant-degrading bacteria in soils; Bogan BW et al.; We report development of a novel parameter for quantifying the amount of humic and fulvic acids per unit surface area in a particular soil . This quantity, the "humic coverage index" (HCI), provides a measurement of the relative spatial extents and/or thicknesses of the humic/fulvic overlayers in different soils, and, therefore, can be used in modeling various soils' behavior in sequestration processes in which humic materials are involved . HCI is herein applied to modeling biodegradation of aromatic and aliphatic hydrocarbons (phenanthrene, pyrene, and hexadecane) by several bacterial strains . Results indicate that, for the cases studies here, contaminant biodegradation is highest at a particular HCI and decreases if the coverage density of humic material is lower or higher than this optimum value . The HCI value at which maximal degradation was observed varied across different strains (indicating strain-specific differences in ability to degrade contaminants sorbed to humic materials) and, to a lesser extent, across different contaminants . The HCI concept is also demonstrated to be useful in explaining soil-, strain-, and contaminant-specific variations in the ability of fulvic acid supplementation to enhance contaminant biodegradation . Finally, we show that, in general, strains which are comparatively better at degrading contaminants in high-HCI soils also show enhanced contaminant mineralization in vitro in the presence of humic acids, such as when hydrocarbons are adsorbed onto these materials.

Environ Sci Technol, 2003 Nov 15, 37(22), 5143 - 9
Capacity for biodegradation of CFCs and HCFCs in a methane oxidative counter-gradient laboratory system simulating landfill soil covers; Scheutz C et al.; The attenuation of methane and four chlorofluorocarbons was investigated in a dynamic methane and oxygen counter-gradient system simulating a landfill soil cover . Soil was sampled at Skellingsted Landfill, Denmark . The soil columns showed a high capacity of methane oxidation with oxidation rates of 210 g m(-2) d(-1) corresponding to a removal efficiency of 81% . CFC-11 and to a lesser extent also CFC-12 were degraded in the active soil columns . The average removal efficiency was 90% and 30% for CFC-11 and CFC-12, respectively . Soil gas concentration profiles indicated that the removal was due to anaerobic degradation, which was verified in anaerobic batch experiments where CFC-11 was rapidly degraded . HCFC-21 and HCFC-22 were also degraded in active soil columns (61% and 41%, respectively), but compared to the CFCs, the degradation was located in the upper oxic part of the column with overlapping gradients of methane and oxygen . High oxidation rates of methane and HCFCs were obtained in soil microcosms incubated with methane . When increasing the column inlet flow, the oxidation zone was moved upward in the column, and the removal efficiency of methane and HCFCs decreased . The removal of CFCs was, however, less affected since the anaerobic zone expanded with increasing inlet flow rates . This study demonstrates the complexity of landfill soil cover systems and shows that both anaerobic and aerobic bacteria may play a very important role in reducing the emission of not only methane but also trace components into the atmosphere.

J Control Release, 2003 Dec 12, 93(3), 259 - 70
In vivo biocompatibility and biodegradation of poly(ethylene carbonate); Dadsetan M et al.; Biodegradation and biocompatibility of poly(ethylene carbonate) (PEC) was examined using an in vivo cage implant system . Exudate analysis showed that PEC and PEC degradation products were biocompatible and induced minimal inflammatory and wound healing responses . Adherent foreign body giant cells (FBGCs) caused pitting on the PEC surface, which led to extensive degradation over time . Data obtained from molecular weight and examination of film cross-sections in the scanning electron microscope (SEM) indicated that PEC underwent surface erosion with no change to the remaining bulk . Attenuated total reflectance infrared (ATR-FTIR) spectroscopy was used to characterize the chemical degradation . Superoxide anion released from inflammatory cells appeared to initiate an "unzipping" mechanism of degradation by deprotonation of PEC hydroxyl end groups . The resulting alkoxide ion participated in a concerted mechanism involving water and the carbonate carbonyl, leading to elimination of ethylene glycol . Carbonate ions decomposed further with release of carbon dioxide to regenerate alkoxide ion.

Biomaterials, 2004 Mar-Apr, 25(7-8), 1279 - 87
Hydroxyapatite/poly(epsilon-caprolactone) composite coatings on hydroxyapatite porous bone scaffold for drug delivery; Kim HW et al.; Hydroxyapatite (HA) porous scaffold was coated with HA and polycaprolactone (PCL) composites, and antibiotic drug tetracycline hydrochloride was entrapped within the coating layer . The HA scaffold obtained by a polymeric reticulate method, possessed high porosity ( approximately 87%) and controlled pore size (150-200 microm) . Such a well-developed porous structure facilitated usage in a drug delivery system due to its high surface area and blood circulation efficiency . The PCL polymer, as a coating component, was used to improve the brittleness and low strength of the HA scaffold, as well to effectively entrap the drug . To improve the osteoconductivity and bioactivity of the coating layer, HA powder was hybridized with PCL solution to make the HA-PCL composite coating . With alteration in the coating concentration and HA/PCL ratio, the morphology, mechanical properties, and biodegradation behavior were investigated . Increasing the concentration rendered the stems thicker and some pores to be clogged; as well increasing the HA/PCL ratio made the coating surface be rough due to the large amount of HA particles . However, for all concentrations and compositions, uniform coatings were formed, i.e., with the HA particles being dispersed homogeneously in the PCL sheet . With the composite coating, the mechanical properties, such as compressive strength and elastic modulus were improved by several orders of magnitude . These improvements were more significant with thicker coatings, while little difference was observed with the HA/PCL ratio . The in vitro biodegradation of the composite coatings in the phosphate buffered saline solution increased linearly with incubation time and the rate differed with the coating concentration and the HA/PCL ratio; the higher concentration and HA amount caused the increased biodegradation . At short period (<2 h), about 20-30% drug was released especially due to free drug at the coating surface . However, the release rate was sustained for prolonged periods and was highly dependent on the degree of coating dissolution, suggesting the possibility of a controlled drug release in the porous scaffold with HA+PCL coating.

Biochem Soc Trans, 2003 Dec, 31(Pt 6), 1335 - 6
Rotting by radicals--the role of cellobiose oxidoreductase?
Mason MG, Nicholls P, Wilson MT.
Cellobiose oxidoreductase is a flavocytochrome secreted by wood-rotting fungi . The structure and functional role of the enzyme are reviewed, and a mechanism through which the enzyme produces superoxide, ferrous iron and hydrogen peroxide is proposed . The reactions of hydroxyl radicals formed by Fenton chemistry are discussed in the context of lignocellulose biodegradation.

Org Biomol Chem, 2003 Nov 7, 1(21), 3663 - 9
Enhancement of the T140-based pharmacophores leads to the development of more potent and bio-stable CXCR4 antagonists; Tamamura H et al.; A CXCR4 antagonistic peptide, T140, and its bio-stable analogs, such as Ac-TE14011, were previously developed . These peptides inhibit the entry of T cell line-tropic strains of HIV-1 (X4-HIV-1) into T cells . Herein, a series of TE14011 analogs having modifications in the N-terminal region were synthesized to develop effective compounds with increased biostability . Among these analogs, 4F-benzoyl-TE14011 (TF14013) showed the strongest anti-HIV activity derived from CXCR4-antagonism, suggesting that a 4-fluorobenzoyl moiety at the N-terminus of T140 analogs constitutes a novel T140-based pharmacophore for CXCR4 antagonists . Structure-activity relationship (SAR) studies on TE14011 analogs with N(alpha)-acylation by several benzoic acid derivatives have disclosed a significant relationship between the anti-HIV activity and the Hammett constant (sigma) of substituted benzoic acids . TF14013 was found to be stable in mouse serum, but not completely stable in rat liver homogenate due to deletion of the C-terminal Arg14-NH2 from the parent peptide . This biodegradation was completely suppressed by N-alkyl-amidation at the C-terminus . Taken together, the enhancement of the T140-based pharmacophores led to development of a novel CXCR4 antagonist, 4F-benzoyl-TE14011-Me (TF14013-Me), which has very high anti-HIV activity and increased biostability.

Water Sci Technol, 2003, 48(6), 187 - 93
Riboflavin as a redox mediator accelerating the reduction of the azo dye mordant yellow 10 by anaerobic granular sludge; Field JA et al.; Azo dyes are important persistent pollutants of textile industry effluents . Reduction of these dyes to their corresponding aromatic amines under anaerobic conditions can be used to initiate biodegradation . Since electron transfer is suggested to be rate limiting, redox mediators are being considered to improve dye reduction kinetics . This study evaluates the use of riboflavin, the redox active moiety of common occurring enzyme cofactors, as a redox mediator to accelerate the reduction of the azo dye, mordant yellow 10 (MY10) . Dye reduction was found to follow zero order kinetics, the total rate constant (Vtotal) could be separated into two components: the rate of reduction due to direct contact between enzymes in the sludge with the dye (Vdirect); and the rate of reduction mediated by riboflavin (Vmediated) . Riboflavin increased the Vtotal by 61% at extremely sub-stoichiometric concentrations of 9.1 micromol l(-1), which corresponded to a molar riboflavin:dye ratio of 1:60 . The accelerating effect of riboflavin displayed saturation kinetics at higher concentrations, with a maximum increase of Vtotal of approximately 2-fold . A model is presented which assumes that Vmediated depends on the activity of riboflavin reductase (RR) and thus follows Michaelis-Menton kinetics with respect to the riboflavin concentration . The half-velocity constant (Km) was very low (6.3 micromol l(-1)), indicating a high affinity of the sludge RR for riboflavin . Both Vdirect and Vmediated were found to be proportional to the assay sludge concentration . The results taken as a whole indicate that vitamin levels of riboflavin can be utilized to improve the kinetics of azo dye reduction during anaerobic treatment.

Water Sci Technol, 2003, 48(6), 133 - 9
Modeling of the Acid Orange 7 anaerobic biodegradation; Mendez-Paz D et al.; It was found that 1-amino-2-naphthol, an intermediate generated during the anaerobic degradation of Acid Orange 7, is a redox mediator which plays a significant role in the transport of electrons to the dye, thus giving to the whole process an autocatalytic nature . Evidences of the autocatalytic behaviour were observed in experimental data previously obtained under batch and fed-batch conditions . In this paper, a kinetic model considering all these factors is proposed and validated . In batch assays, this model agrees satisfactorily with the experimental data . In the case of fed-batch assays, the autocatalytic model only can be applied satisfactorily after the first feeding, since the degradation of Acid Orange 7 after the second and third feedings followed a first-order kinetic . This fact can be explained due to the presence of the redox mediator previously generated during the reactions that took place after the first feeding.

Water Sci Technol, 2003, 48(6), 125 - 31
Anaerobic biodegradation of BTEX using Mn(IV) and Fe(III) as alternative electron acceptors; Villatoro-Monzon WR et al.; Anaerobic BTEX biodegradation was tested in batch experiments using an anaerobic sediment as inoculum under Fe(III) and Mn(IV) reducing conditions . All BTEX were degraded under the conditions tested, specially under Mn(IV) reducing conditions, where benzene was degraded at a rate of 0.8 micromol l(-1) d(-1), significantly much faster than Fe(III) reducing conditions . Under Fe(III) reducing conditions, ethylbenzene was the compound that degraded at the faster rate of 0.19 micromol l(-1) d(-1) . Mn(IV) reducing conditions are energetically more favourable than Fe(III), therefore, BTEX were more rapidly degraded under Mn(IV) reducing conditions . These results represent the first report of the degradation of benzene with Mn(IV) as the final electron acceptor . Amorphous manganese oxide is a natural widely distributed metal in groundwater, where it can be microbiologically reduced, leading to the degradation of monoaromatic compounds.

Environ Pollut, 2004, 127(3), 425 - 30
Biodegradation of nonylphenol in river sediment; Yuan SY et al.; We investigated the biodegradation of nonylphenol monoethoxylate (NP1EO) and nonylphenol (NP) by aerobic microbes in sediment samples collected at four sites along the Erren River in southern Taiwan . Aerobic degradation rate constants (k1) and half-lives (t1/2) for NP (2 microg g(-1)) ranged from 0.007 to 0.051 day(-1) and 13.6 to 99.0 days, respectively; for NP1EO (2 microg g(-1)) the ranges were 0.006 to 0.010 day(-1) and 69.3 to 115.5 days . Aerobic degradation rates for NP and NP1EO were enhanced by shaking and increased temperature, and delayed by the addition of Pb, Cd, Cu, Zn, phthalic acid esters (PAEs), and NaCl, as well as by reduced levels of ammonium, phosphate, and sulfate . Of the microorganism strains isolated from the sediment samples, we found that strain JC1 (identified as Pseudomonas sp.) expressed the best biodegrading ability . Also noted was the presence of 4'-amino-acetophenone, an intermediate product resulting from the aerobic degradation of NP by Pseudomonas sp.

Water Res, 2004 Jan, 38(1), 97 - 102
Biodegradation of p-chlorophenol by a microalgae consortium; Lima SA et al.; An aquatic community was recovered from a waste discharge container fed with several aromatic pollutants . After 3 months of selective enrichment with p-chlorophenol and p-nitrophenol, two microalgae species, Chlorella vulgaris and Coenochloris pyrenoidosa, were recovered from the microbial consortium . As an axenic culture, this microalgae consortium was able to remove p-chlorophenol under different photo-regimes . Cultures grown under a 24h light regime were capable of biodegrading 50mg l(-1) of p-chlorophenol within 5 days . Addition of zeolite, an adsorbing material, did not improve the p-chlorophenol removal . However, when p-chlorophenol at 150mgl(-1) was fed to the culture supplemented with zeolite, the growth rate of the consortium improved, but the lag phase was longer (16 against 14 days in the absence of zeolite).

Nature, 2003 Nov 20, 426(6964), 344 - 52
Biological activity in the deep subsurface and the origin of heavy oil; Head IM et al.; At temperatures up to about 80 degrees C, petroleum in subsurface reservoirs is often biologically degraded, over geological timescales, by microorganisms that destroy hydrocarbons and other components to produce altered, denser 'heavy oils' . This temperature threshold for hydrocarbon biodegradation might represent the maximum temperature boundary for life in the deep nutrient-depleted Earth . Most of the world's oil was biodegraded under anaerobic conditions, with methane, a valuable commodity, often being a major by-product, which suggests alternative approaches to recovering the world's vast heavy oil resource that otherwise will remain largely unproduced.

Biofouling, 2003 Apr, 19 Suppl, 83 - 90
Biodegradation-based polymer surface erosion and surface renewal for foul-release at low ship speeds; Yu J; Non-toxic foul-release provides an environmentally friendly and sustainable technical solution to control micro- and/or macrofouling on ships' hulls . Silicone-based coatings have been used for foul-release at high or moderate ship speeds (> 15 knots) . To remove the fouling from slower ships (< 15 knots), the macrofoulers in particular, biodegradable polymers may be used to make the coating surface self-renewable . Synthesized by micro-organisms for carbon and energy storage under controlled conditions, polyhydroxyalkanoates (PHAs) are hydrophobic bipolymers that are gradually decomposed into CO2 and water in the environment . Because of their hydrophobic property and lack of hydrolysis in sterile aqueous solution, PHAs do not dissolve in water, but erode at the polymer surface (2-5 microns in depth) catalyzed exclusively by microbial enzymes (depolymerases) that are attached on the solid surface . The thin-layer surface erosion behaves like a self-renewable surface coating, which approaches a constant renewal rate at a relative hydraulic speed as low as 3 knots . A turbulence eddy model is used to describe the effect of energy consumption per mass of liquid on the turbulent shear stress and the surface renewal rate . Furthermore, the polymer biodegradation or surface renewal rate can be controlled within a broad range by blending the material with polymers such as poly (epsilon-caprolactone) (PCL) . The biodegradation of binary blends of PHA/PCL of different compositions was quantitatively monitored by means of weight loss and Raman spectroscopy.

Biomaterials, 2004 Mar, 25(6), 1049 - 58
Hydroxyapatite-chitin materials as potential tissue engineered bone substitutes; Ge Z et al.; Hydroxyapatite (HA) in 25%, 50% and 75% w/w fractions was incorporated into chitin solutions and processed into air- and freeze-dried materials . These HA-chitin materials were exposed to cell cultures and implanted into the intramusculature of a rat model . The HA-chitin materials were found to be non-cytotoxic and degraded in vivo . The presence of the HA filler enhanced calcification as well as accelerated degradation of the chitin matrix . The freeze-dried HA-chitin matrixes were selected for further cell seeding experiments because of their porous nature . Mesenchymal stem cells harvested from NZW rabbits were induced into osteoblasts in vitro using dexamethasone . These osteoblasts were cultured for 1 week, statically loaded onto the porous HA-chitin matrixes and implanted into bone defects of the rabbit femur for 2 months . Histology of explants showed bone regeneration with biodegradation of the HA-chitin matrix . Similarly, green fluorescence protein (GFP) transfected MSC-induced osteoblasts were also loaded onto porous HA-chitin matrixes and implanted into the rabbit femur . The results from GFP-transfected MSCs showed that loaded MSCs-induced osteoblasts did not only proliferate but also recruited surrounding tissue to grow in . This study demonstrates the potential of HA-chitin matrixes as a good substrate candidate for tissue engineered bone substitute.

J Biomed Mater Res A, 2003 Dec 1, 67(3), 1033 - 43
The study of the sterilization effect of gamma ray irradiation of immobilized collagen polypropylene nonwoven fabric surfaces; Tyan YC et al.; Exposure to gamma ray irradiation is a frequent, clean, and superior method used to prevent bacterial contamination of sterilized biomedical end products . However, the potential damage induced by gamma ray irradiation of collagen is of concern because of the decay of bioactivity, which correlates with considerable structural alterations . In this experiment, antenna-coupling microwave plasma was utilized to activate nonwoven polypropylene (PP) fabric, and then the sample was grafted to acrylic acid (AAc) . Type III collagen was immobilized by using water-soluble 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide as a coupling agent . The collagen-immobilized samples, with temperatures of under 4 degrees C, were exposed to gamma ray irradiation at different dose intervals . Gamma ray irradiation was applied to evaluate the bioactivity on the collagen-immobilized nonwoven polypropylene and to determine the results of sterilization . Five kinds of sterilization index bacteria, all subject to Good Manufacturing Practice (GMP) criteria, were applied as a standard plate-count sterilization test . Our experimental results demonstrate that in human plasma incubated with various intervals of gamma ray irradiation, fibrinogen concentration decreases while platelet and red blood cell adhesion increase . However, the dose required for thrombination demonstrated a significant change in gamma ray irradiation exposure of fewer than 10 KGy (p = 0.05) . The decay of bioactivity of the gamma-ray-irradiated collagen-bonded surfaces was evaluated and indicated that the decrease of R-CONHR', the degradation of amides ({broken bond}C{bond}N bonds of collagen and formation of the ROCNH(2) and O{double bond}CR' bonds), and the increase of C{bond}O, C{double bond}O bonds gradually may damage collagen by increasing the intervals of gamma ray irradiation . These effects considerably influence the bioactivity of the collagen-bonded fabric . It is clear that gamma ray irradiation exposure of approximately 10 KGy has the potential of moderating the bioactivities of collagen and therefore likely is a vital factor in the acceleration of biodegradation . The dose required for thrombination and sterilization reaches significance at 7.5 KGy .

Can J Microbiol, 2003 Aug, 49(8), 508 - 13
Influence of peanut oil on microbial degradation of polycyclic aromatic hydrocarbons; Pannu JK et al.; Peanut oil amendment (0.1%-0.2% (v/v)) increased the biodegradation of various polycyclic aromatic hydrocarbons (PAHs) by 15%-80% with a mixed bacterial culture and a pure culture of Comamonas testosteroni in aqueous media and in PAH-contaminated weathered soil slurry systems . The stimulatory effect on biodegradation was more pronounced with the high molecular weight PAHs (e.g., >3 rings) . The presence of peanut oil also accelerated the biodegradation of PAHs sorbed onto activated carbon, indicating its potential application in the bioregeneration of activated carbon.

Biomaterials, 2004 Feb, 25(4), 699 - 706
Vascularization in vivo caused by the controlled release of fibroblast growth factor-2 from an injectable chitosan/non-anticoagulant heparin hydrogel; Fujita M et al.; Addition of various heparinoids to the lactose-introduced, water-soluble chitosan (CH-LA) aqueous solution produces an injectable chitosan/heparinoid hydrogel . In the present work, we examined the capability of the chitosan/non-anticoagulant heparin (periodate-oxidized (IO(4)-) heparin) hydrogel to immobilize fibroblast growth factor (FGF)-2, as well as the controlled release of FGF-2 molecules from the hydrogel in vitro and in vivo . The hydrogel was biodegraded in about 20 days after subcutaneous injection into the back of a mouse . When the FGF-2-incorporated hydrogel was subcutaneously injected into the back of both mice and rats, a significant neovascularization and fibrous tissue formation were induced near the injected site . These results indicate that the controlled release of biologically active FGF-2 molecules is caused by biodegradation of the hydrogel, and that subsequent induction of the vascularization occurs.

J Contam Hydrol, 2003 Dec, 67(1-4), 269 - 99
Inverse modeling of BTEX dissolution and biodegradation at the Bemidji, MN crude-oil spill site; Essaid HI et al.; The U.S . Geological Survey (USGS) solute transport and biodegradation code BIOMOC was used in conjunction with the USGS universal inverse modeling code UCODE to quantify field-scale hydrocarbon dissolution and biodegradation at the USGS Toxic Substances Hydrology Program crude-oil spill research site located near Bemidji, MN . This inverse modeling effort used the extensive historical data compiled at the Bemidji site from 1986 to 1997 and incorporated a multicomponent transport and biodegradation model . Inverse modeling was successful when coupled transport and degradation processes were incorporated into the model and a single dissolution rate coefficient was used for all BTEX components . Assuming a stationary oil body, we simulated benzene, toluene, ethylbenzene, m,p-xylene, and o-xylene (BTEX) concentrations in the oil and ground water, respectively, as well as dissolved oxygen . Dissolution from the oil phase and aerobic and anaerobic degradation processes were represented . The parameters estimated were the recharge rate, hydraulic conductivity, dissolution rate coefficient, individual first-order BTEX anaerobic degradation rates, and transverse dispersivity . Results were similar for simulations obtained using several alternative conceptual models of the hydrologic system and biodegradation processes . The dissolved BTEX concentration data were not sufficient to discriminate between these conceptual models . The calibrated simulations reproduced the general large-scale evolution of the plume, but did not reproduce the observed small-scale spatial and temporal variability in concentrations . The estimated anaerobic biodegradation rates for toluene and o-xylene were greater than the dissolution rate coefficient . However, the estimated anaerobic biodegradation rates for benzene, ethylbenzene, and m,p-xylene were less than the dissolution rate coefficient . The calibrated model was used to determine the BTEX mass balance in the oil body and groundwater plume . Dissolution from the oil body was greatest for compounds with large effective solubilities (benzene) and with large degradation rates (toluene and o-xylene) . Anaerobic degradation removed 77% of the BTEX that dissolved into the water phase and aerobic degradation removed 17% . Although goodness-of-fit measures for the alternative conceptual models were not significantly different, predictions made with the models were quite variable.

Water Res, 2003 Dec, 37(20), 4843 - 54
A general model for multiple substrate biodegradation . Application to co-metabolism of structurally non-analogous compounds; Brandt BW et al.; The availability of multiple carbon/energy sources, as is common in wastewater treatment plants, often enhances the biodegradation of recalcitrant compounds . In this paper, we classify and model different modes of multiple substrate utilization in a systematic way, using the concept of synthesizing unit . According to this concept, substrates can be substitutable or complementary; their uptake (or processing) can be sequential or parallel . We show how the different modes of multiple substrate interaction can be described by a single general model . From the general model, we derive simple expressions for co-metabolism of substrates that are not structurally analogous . Both the general and the specific co-metabolism model have the advantage that they can be used in combination with any microbial growth model . To test the co-metabolism model's realism, we confront it with experimental data . The results attained with the co-metabolism model support that the general model constitutes a useful framework for modeling aspects of multiple substrate utilization.

Chemosphere, 2004 Feb, 54(6), 777 - 88
Transformation of effluent organic matter during subsurface wetland treatment in the Sonoran Desert; Quanrud DM et al.; The fate of dissolved organic matter (DOM) during subsurface wetland treatment of wastewater effluent in a hot, semi-arid environment was examined . The study objectives were to (1) discern changes in the character of dissolved organics as consequence of wetland treatment (2) establish the nature of wetland-derived organic matter, and (3) investigate the impact of wetland treatment on the formation potential of trihalomethanes (THMs) . Subsurface wetland treatment produced little change in DOM polarity (hydrophobic-hydrophilic) distribution . Biodegradation of labile effluent organic matter (EfOM) and internal loading of wetland-derived natural organic matter (NOM) together produced only minor changes in the distribution of carbon moieties in hydrophobic acid (HPO-A) and transphilic acid (TPI-A) isolates of wetland effluent . Aliphatic carbon decreased as a percentage of total carbon during wetland treatment . The ratio of atomic C:N in wetland-derived NOM suggests that its character is determined by microbial activity . Formation of THMs upon chlorination of HPO-A and TPI-A isolates increased as a consequence of wetland treatment . Wetland-derived NOM was more reactive in forming THMs and less biodegradable than EfOM . For both HPO-A and TPI-A fractions, relationships between biodegradability and THM formation potential were similar among EfOM and NOM isolates; the less biodegradable isolates exhibited greater THM formation potential.

Chemosphere, 2004 Feb, 54(6), 725 - 33
Isolation and identification of intermediates from biodegradation of low chlorinated biphenyls (Delor-103); Triska J et al.; Microorganism Pseudomonas species P2 metabolizes polychlorinated biphenyls (PCBs) and biphenyl, producing the whole spectrum of intermediates, among them coloured intermediates, which are suitable for the monitoring of PCBs degradation by optical sensors . Knowledge of chemical structures and conditions of development of colour metabolites is necessary for application of optical analytical methods . The main goal of this work was the isolation and identification of intermediates from the biodegradation of the mixture of low chlorinated biphenyls (Delor-103), which is based on the solid phase extraction (SPE) of the whole mixture using LiChrolut EN cartridges, then silylation of the extract as one way to the identification of one part of intermediates by GC-MS, and acetylation of the extract as a way for the further concentration and analysis of more polar chlorobiphenylols and chlorobiphenyldiols . The combination of SPE and following acetylation allows to obtain chlorobiphenylols and chlorobiphenyldiols as an almost pure fraction . The acetylation method could be also used instead SPE procedure with the same final concentration effect . Using the simulation mass spectrometry program, two new compounds, dihydrodihydroxytrichloro- and tetrahydrodihydroxytrichlorobiphenyl, as silylderivatives, were identified.

Chemosphere, 2004 Feb, 54(6), 717 - 24
Behaviour of simazine in soil amended with the final residue of the olive-oil extraction process; Albarran A et al.; Addition of organic wastes to agricultural soils is becoming a common practice as a disposal strategy and to improve the physical and chemical soil properties . However, in order to optimise the use of organic wastes as soil amendments, their effect on the behaviour of other compounds that are also used in agriculture, such as pesticides, needs to be assessed . In this work, we have investigated the effects of the addition of the final solid residue of the new technology of olive-oil extraction (extracted alperujo or solid olive-mill waste, SOMW2) on the sorption, degradation and leaching of the herbicide simazine in a sandy loam soil . The results are compared with those of a previous study, where the intermediary by-product of the olive-oil processing technology (unextracted alperujo or SOMW1) was applied to the same soil . The soil was amended in the laboratory with SOMW2 at two different rates (5% and 10% w/w) . Simazine sorption isotherms showed a great increase in herbicide sorption after SOMW2 addition to soil . SOMW2 addition also increased sorption irreversibility . Incubation studies revealed reduced biodegradation of simazine in the soil amended with SOMW2 compared to the unamended soil . Breakthrough curves of simazine in handpacked soil columns showed that SOMW2 addition retarded the vertical movement of the herbicide through the soil and greatly reduced the amount of herbicide available for leaching . Interestingly, the results were quantitatively different from those obtained for the intermediary by-product SOMW1, illustrating the importance of the specific characteristics of the organic amendment in determining its effect on pesticide behaviour.

Proc Natl Acad Sci U S A, 2003 Nov 11, 100(23), 13591 - 6 Epub 2003 Nov 03.
Discovery of a bacterium, with distinctive dioxygenase, that is responsible for in situ biodegradation in contaminated sediment; Jeon CO et al.; Microorganisms maintain the biosphere by catalyzing biogeochemical processes, including biodegradation of organic chemical pollutants . Yet seldom have the responsible agents and their respective genes been identified . Here we used field-based stable isotopic probing (SIP) to discover a group of bacteria responsible for in situ metabolism of an environmental pollutant, naphthalene . We released 13C-labeled naphthalene in a contaminated study site to trace the flow of pollutant carbon into the naturally occurring microbial community . Using GC/MS, molecular biology, and classical microbiological techniques we documented 13CO2 evolution (2.3% of the dose in 8 h), created a library of 16S rRNA gene clones from 13C labeled sediment DNA, identified a taxonomic cluster (92 of 95 clones) from the microbial community involved in metabolism of the added naphthalene, and isolated a previously undescribed bacterium (strain CJ2) from site sediment whose 16S rRNA gene matched that of the dominant member (48%) of the clone library . Strain CJ2 is a beta proteobacterium closely related to Polaromonas vacuolata . Moreover, strain CJ2 hosts the sequence of a naphthalene dioxygenase gene, prevalent in site sediment, detected before only in environmental DNA . This investigative strategy may have general application for elucidating the bases of many biogeochemical processes, hence for advancing knowledge and management of ecological and industrial systems that rely on microorganisms.

Environ Sci Technol, 2003 Oct 15, 37(20), 4751 - 60
Sequential chemical oxidation and aerobic biodegradation of equivalent carbon number-based hydrocarbon fractions in jet fuel; Xie G et al.; Remediation of petroleum mixtures is complicated by the differing environmental degradabilities of hundreds of individual hydrocarbons in the mixtures . By grouping the individual hydrocarbons into a few fractions based on equivalent carbon number (EC), the present study examined the chemical and biological degradation of the fractions . With or without prechemical oxidation (25 days) by three oxidants (KMnO4, H202, MgO2), sterile and live microcosms were constituted with aquifer samples for aerobic biodegradation (134 days) of JP-4 jet fuel . Eighty-seven hydrocarbons were recovered and grouped into nine EC fractions . The apparent removal and actual transformation rate constants were estimated for both chemical and biological degradations . The data show that prechemical oxidations facilitated removal of total petroleum hydrocarbons (TPH) (up to 80%) within shorter times (<50 days) than biological alone . KMnO4 and H202 were better oxidants in terms of mass reduction in shorter times yet to some extent inhibited the subsequent microbial activity . MgO2 was a moderate oxidant with less inhibition of microbial activity . Selective degradation of the EC fractions was observed for both chemical and biological processes . The biological processes were much less effective than the prechemical oxidations in transforming aromatic fractions, the more toxic fractions . The favorable substrates (i.e., aliphatic EC approximately 10) for microbial growth were also those most subject to chemical oxidation . The results suggest that for remediation of petroleum contaminants, sequential chemical and biological technologies may surpass biological alone and more moderate oxidants such as MgO2 may be better candidates . More work is needed on the optimal dose and residence time for applied oxidants and on the application to engineering design and formulation of cleanup standards.

Prikl Biokhim Mikrobiol, 2003 Sep-Oct, 39(5), 555 - 60
{Effect of wood modification on lignin consumption and synthesis of lignolytic enzymes by the fungus Panus (Lentinus) tigrinus}; Kadimaliev DA et al.; Lignin consumption and synthesis of lignolytic enzymes by the fungus Panus (Lentinus) tigrinus cultivated on solid phase (modified and unmodified birch and pine sawdusts) were studied . The fungus grew better and consumed more readily the birch lignin than the pine wood . Peroxidase activity was higher in the case of pine sawdust; laccase and lignolytic activities, in the case of birth sawdust . Treatment with ammonia or sulfuric acid decreased lignin consumption by the fungus cultivated on either medium . Modification of sawdust by ultrasound increased lignin consumption and may be recommended for accelerating biodegradation of lignocellulose substrates.

Environ Int, 2004 Jan, 29(7), 887 - 94
Preliminary exploration of the relationships between soil characteristics and PAH desorption and biodegradation; Hwang S et al.; Desorption and biodegradation of pyrene (PYR) were investigated and their relationships to soil characteristics were addressed . The results indicated that maximum achievable desorption was 30.2, 10.4, and 1.0 mg/kg for soils that had 1.7, 2.2, and 4.4 wt.% of expandable clays (smectite and vermiculite), respectively . Neither dissolved organic matter (DOM) nor total clay amounts made a good prediction of the desorption trend . Subsequently, the ease of desorption facilitated a faster aqueous biodegradation rate . The slowest aqueous biodegradation rate, 0.02 l/h, was achieved for the soil system that had the greatest amount of expandable clays, whereas the soil containing 1.7% expandable clays only achieved 0.73 l/h . The soil with 2.2% expandable clays depicted 0.41 l/h of aqueous biodegradation rate . A good linear correlation was obtained between maximum achievable desorption and aqueous biodegradation rate (R(2)=0.92) . Soil analysis revealed that the total (soil+water) biodegradation reached was 65%, 78.3%, and 81.8% of the initial concentration (100 mg/kg) for the sandy clay loam (Colombian), sandy loam (Ohio), and silty loam (New Mexico) soils, respectively . This biodegradation extent was also in good agreement of expandable clay amount . Although aqueous PYR bioavailability was limited due to the strong association with the expandable clays, microbial movement and adhesion to those clays seemed to result in a great extent of the soil-phase biodegradation.

Environ Toxicol Chem, 2003 Nov, 22(11), 2630 - 8
Effects of surfactants on the dechlorination of chlorinated ethenes; McGuire T et al.; The influence of surfactants on a perchloroethene (PCE) dechlorinating mixed culture was investigated in laboratory experiments . Surfactants (Steol CS-330, Aerosol MA 80-I, alpha olefin sulfonate 14 to 16, Neodol 25-7, Tween 80, alkyl polyglycoside, C16TAB {trimethylammonium bromide}, and sodium dodecyl sulfate) were evaluated for their effects on the rate and extent of PCE reductive dechlorination and their potential biodegradation by the mixed culture . Limited, if any, surfactant biodegradation was observed for the surfactants tested, and all surfactants impaired dechlorination in either the rate of PCE dechlorination or the terminal dechlorination products observed . Based on initial testing, a nonionic surfactant, Tween 80, and an anionic surfactant, Steol CS-330, were selected for additional investigation . Dechlorination of PCE to dichloroethene (DCE), vinyl chloride (VC), and ethene (ETH) occurred in all Tween 80-amended microcosms, with a depressed rate of ETH production as the only adverse effect . Steol CS-330, however, inhibited dechlorination beyond DCE at all surfactant concentrations exceeding 25 mg/L . Attempts to acclimate a culture to Steol CS-330 were unsuccessful . Inhibition of VC and ETH production was reversible on dilution of the surfactant to a concentration of 10 mg/L or less, indicating that surfactant interactions with the enzyme system responsible for reductive dechlorination of DCE may be the cause of inhibition.

Biomaterials, 2004 Feb, 25(3), 483 - 9
A hyaluronan-based nerve guide: in vitro cytotoxicity, subcutaneous tissue reactions, and degradation in the rat; Jansen K et al.; We investigated possible cytotoxic effects, biocompatibility, and degradation of a hyaluronan-based conduit for peripheral nerve repair . We subjected the conduits to an in vitro fibroblast cytotoxicity test and concluded that the conduits were not cytotoxic . Subsequently, we implanted the conduits subcutaneously in rats, in order to investigate tissue reactions and biodegradation . Initially, a fibrin matrix was formed around the material, while the surroundings were relatively quiet . Macrophages (MO) migrated to the conduits and formed giant cells next to the material after 5 days . The maximum presence of MO was found after 3-6 weeks . The appearance of MHC class II cells showed a similar pattern . Highest numbers of giants reached a maximum after 6-12 weeks . Angiogenesis was started in the surroundings of the hyaluronan-based conduit within a few days . Massive ingrowth of blood vessels into the biomaterial was found after 6 weeks as well as cellular ingrowth into the lumen of the tube . At that time the tubular structure of the conduit was lost and loose biomaterial fibers were observed . The results show that a hyaluronan-based conduit is not cytotoxic and shows good biocompatibility . Such a conduit may be suitable as a guide in peripheral nerve repair.

Bioresour Technol, 2004 Jan, 91(1), 69 - 75
Decolorization of reactive azo dyes by Cunninghamella elegans UCP 542 under co-metabolic conditions; Ambrosio ST et al.; The inappropriate disposal of dyes in wastewater constitutes an environmental problem and can cause damage to the ecosystem . Alternative treatments have been reported that fungi are particularly effective in the decolorization of textile effluents . The decolorization of dyes with different molecular structures by Cunninghamella elegans was evaluated under several media conditions . The decolorization procedures consisted of adding 72 h of mycelium into the culture medium containing either orange or reactive black or reactive red or a mixture of these dyes in the presence or absence of sucrose and/or peptone . The decolorization profile was highly dependent upon the incubation time, the molecular structure of the dye and presence or absence of co-substrates . The presence of sucrose or both sucrose and peptone significantly increased the decolorization of the solutions, however, the presence of only the nitrogen source suppressed it . The ultraviolet spectra of the solutions before and after decolorization suggested the occurrence of biodegradation in addition to the biosorption of the dyes . All tested dyes, except for the reactive black, caused inhibition of respiration of Escherichia coli, which suggested that toxic metabolites were produced.

Chemosphere, 2004 Jan, 54(4), 551 - 9
Biodegradability of wheat gluten based bioplastics; Domenek S et al.; A large variety of wheat gluten based bioplastics, which were plasticized with glycerol, were subjected to biodegradation . The materials covered the total range available for the biochemical control parameter Fi, which expresses the percentage of aggregated proteins . This quantity can be related to the density of covalent crosslinks in the wheat gluten network, which are induced by technological treatments . The biodegradability tests were performed in liquid medium (modified Sturm test) and in farmland soil . All gluten materials were fully degraded after 36 days in aerobic fermentation and within 50 days in farmland soil . No significant differences were observed between the samples . The mineralization half-life time of 3.8 days in the modified Sturm test situated gluten materials among fast degrading polymers . The tests of microbial inhibition experiments revealed no toxic effects of the modified gluten or of its metabolites . Thus, the protein bulk of wheat gluten materials is non-toxic and fully biodegradable, whatever the technological process applied.

Biomaterials, 2004 Jan, 25(1), 85 - 96
Biodegradable poly(ether ester urethane)urea elastomers based on poly(ether ester) triblock copolymers and putrescine: synthesis, characterization and cytocompatibility; Guan J et al.; Polymers with elastomeric mechanical properties, tunable biodegradation properties and cytocompatibility would be desirable for numerous biomedical applications . Toward this end a series of biodegradable poly(ether ester urethane)urea elastomers (PEEUUs) based on poly(ether ester) triblock copolymers were synthesized and characterized . Poly(ether ester) triblock copolymers were synthesized by ring-opening polymerization of epsilon-caprolactone with polyethylene glycol (PEG) . PEEUUs were synthesized from these triblock copolymers and butyl diisocyanate, with putrescine as a chain extender . PEEUUs exhibited low glass transition temperatures and possessed tensile strengths ranging from 8 to 20MPa and breaking strains from 325% to 560% . Increasing PEG length or decreasing poly(caprolactone) length in the triblock segment increased PEEUU water absorption and biodegradation rate . Human umbilical vein endothelial cells cultured in a medium supplemented with PEEUU biodegradation solution suggested a lack of degradation product cytotoxicity . Endothelial cell adhesion to PEEUUs was less than 60% of tissue culture polystyrene and was inversely related to PEEUU hydrophilicity . Surface modification of PEEUUs with ammonia gas radio-frequency glow discharge and subsequent immobilization of the cell adhesion peptide Arg-Gly-Asp-Ser increased endothelial adhesion to a level equivalent to tissue culture polystyrene . These biodegradable PEEUUs thus possessed properties that would be amenable to applications where high strength and flexibility would be desirable and exhibited the potential for tuning with appropriate triblock segment selection and surface modification.

J Dent Res, 2003 Nov, 82(11), 903 - 8
Regulating bone formation via controlled scaffold degradation; Alsberg E et al.; It is widely assumed that coupling the degradation rate of polymers used as cell transplantation carriers to the growth rate of the developing tissue will improve its quantity or quality . To test this hypothesis, we developed alginate hydrogels with a range of degradation rates by gamma-irradiating high-molecular-weight alginate to yield polymers of various molecular weights and structures . Decreasing the size of the polymer chains increased the degradation rate in vivo, as measured by implant retrieval rates, masses, and elastic moduli . Rapidly and slowly degrading alginates, covalently modified with RGD-containing peptides to control cell behavior, were then used to investigate the effect of biodegradation rate on bone tissue development in vivo . The more rapidly degrading gels led to dramatic increases in the extent and quality of bone formation . These results indicate that biomaterial degradability is a critical design criterion for achieving optimal tissue regeneration with cell transplantation.

J Control Release, 2003 Oct 30, 92(3), 301 - 13
In vivo anti-tumor effect through the controlled release of cisplatin from biodegradable gelatin hydrogel; Konishi M et al.; This paper is an investigation to achieve the in vivo controlled release of cisplatin (CDDP) from a biodegradable hydrogel . Hydrogels with different water contents were prepared through the chemical crosslinking of gelatin by various concentrations of glutaraldehyde . The gelatin hydrogel incorporating CDDP (CDDP-hydrogel) was prepared by allowing CDDP aqueous solution to sorb into the freeze-dried hydrogel . Irrespective of the hydrogel water content, approximately 10-30% of incorporated CDDP was released from the hydrogel in phosphate-buffered saline solution (PBS) at 37 degrees C within the initial 6 h, while little release was observed thereafter . The amount of CDDP released initially decreased with an increase in the time period of CDDP sorption . When intratumorally applied into Meth-AR-1 tumor-bearing mice, CDDP-hydrogel suppressed in vivo tumor growth to a significantly higher extent than free CDDP at the same dose . The survival rate was significantly higher by the application of CDDP-hydrogel of 40 microg CDDP . The CDDP concentration in the tumor tissue was maintained at a higher level for a longer time period than that of free CDDP . However, no problematic change in the mouse body and blood biochemical parameters was observed on the application of the CDDP-hydrogel . The time course of in vivo CDDP retention was in a good accordance with that of hydrogel remaining . Larger CDDP release was observed from the front surface of hydrogel onto which free CDDP was sorbed, than the back surface of hydrogel . These findings demonstrate that the controlled release of CDDP was based on biodegradation of the hydrogel carrier, but not simple diffusion of CDDP . It is possible that the CDDP molecules immobilized in the gelatin hydrogel were released from the hydrogel only when the hydrogel was degraded to generate some water-soluble gelatin fragments.

J Contam Hydrol, 2003 Nov, 66(3-4), 201 - 17
A sequential zero valent iron and aerobic biodegradation treatment system for nitrobenzene; Bell LS et al.; The remediation of nitroaromatic contaminated groundwater is sometimes difficult because nitroaromatic compounds are resistant to biodegradation and, when they do transform, the degradation of the products may also be incomplete . A simple nitroaromatic compound, nitrobenzene, was chosen to assess the feasibility of an in situ multi-zone treatment system at the laboratory scale . The proposed treatment system consists of a zero valent granular iron zone to reduce nitrobenzene to aniline, followed by a passive oxygen release zone for the aerobic biodegradation of the aniline daughter product using pristine aquifer material from Canadian Forces Base (CFB) Borden, Ontario, as an initial microbial source . In laboratory batch experiments, nitrobenzene was found to reduce quickly in the presence of granular iron forming aniline, which was not further degraded but remained partially sorbed onto the granular iron surface . Aniline was found to be readily biodegraded with little metabolic lag under aerobic conditions using the pristine aquifer material . A sequential column experiment, containing a granular iron reducing zone and an aerobic biodegradation zone, successively degraded nitrobenzene and then aniline to below detection limits (0.5 microM) without any noticeable reduction in hydraulic conductivity from biofouling, or through the formation of precipitates.

Biomed Pharmacother, 2003 Oct, 57(8), 351 - 8
Dynorphin-A(1-17) decreases nitric oxide release and cytotoxicity induced with lipopolysaccharide plus interferon-gamma in murine macrophage cell line J774; Gabrilovac J et al.; Nitric oxide (NO) is an important mediator of cytotoxicity caused by macrophages or by their resident counterpart in brain-glial cells . Modulation of NO release by both activated macrophages and glial cells has been reported in the presence of endogenous (peptide) and synthetic (non-peptide) agonists with kappa opioid-receptors (KOR) selectivity . The data obtained with macrophages and glial cells are contradictory: enhanced NO release by mouse macrophages was reported in the presence of synthetic agonist of KOR selectivity (Neuropeptides 32 (1998) 287), and decreased NO release by glial cells, in the presence of dynorphin-A((1-8)), endogenous opioid peptide with KOR selectivity (J . Biomed . Sci . 7 (2000) 241) . In this study, we used a murine cell line J774 of macrophage origin and examined the effect of dynorphin-A((1-17)), endogenous opioid peptide with selectivity for KOR, on NO release induced with lipopolysaccharide (LPS) plus interferon-gamma (IFN-gamma) . Dynorphin-A((1-17)) was chosen since in comparison to dynorphin-A((1-13)), it is more resistant to biodegradation (Peptides 17 (1996) 983), and its effects during prolonged treatment of cells could be more pronounced . The effect of dynorphin-A((1-17)) on NO release was compared to its effect on cytotoxicity, induced with LPS plus IFN-gamma . The data obtained have shown that activation-induced NO release by J774 cells is decreased in the presence of dynorphin-A((1-17)) . This was associated with deceased LPS and IFN-gamma-induced cytotoxicity of J774 cells, suggesting their causal relationship . Neither of the observed effects of dynorphin-A((1-17)) could be prevented with the KOR selective antagonist, norbinaltorphimine, suggesting that they are mediated via non-opioid mechanism . By diminishing NO release dynorphin-A((1-17)) may affect cytotoxic ability of macrophages, but may also beneficially influence inflammation-induced damage of local tissue.

Environ Toxicol Chem, 2003 Oct, 22(10), 2251 - 7
Quantitative structure-biodegradation relationships for ortho-substituted biphenyl compounds oxidized by Methylosinus trichosporium OB3b; Lindner AS et al.; Methanotrophs, bacteria that thrive in the presence of stable methane and oxygen concentrations, can cometabolically oxidize ortho-substituted biphenyls to yield a variety of hydroxylated products . Despite awareness of the susceptibility of ortho-substituted biphenyls and other aromatic compounds to methanotrophic oxidation, the molecular properties relevant for predicting rates of methanotrophic oxidation are unknown . To this end, we have developed quantitative structure-biodegradation relationships using oxygen uptake activity by the type 2 methanotroph . Methylosinus trichosporium OB3b, expressing the soluble form of methane monooxygenase and in the presence of nine ortho-substituted biphenyls . Multivariate analysis yielded the strongest correlations using the initial slope of the oxygen uptake rate versus substrate concentration curve as the dependent variable . Quantum mechanical descriptors, including the sum of carbon charges on the substituted ring, the charge on the substituted carbon, and the width of compound calculated using computationally derived bond lengths and dihedral angles, correlated more strongly with oxygen uptake activity than did empirically derived electronic descriptors . The resulting models suggest a significant influence of substituent electronic nature and size and the involvement of the substituted carbon site in the oxidation of these compounds by M . trichosporium OB3b.

Biotechnol Adv, 1993, 11(3), 701 - 10
Assessment of solid state fermentation by a biolectronic artificial nose; Wang HH; The use of a bioelectronic artificial nose (AN) is described for on-site-monitoring to assess the reaction patterns of solid state fermentations for control of microclimate at sampling site . The nose consists of fractionated olfactory cell proteins of bullfrog (as a receptor membrane) coated on a piezoelectric quartz crystal connected to an oscillator and a data recorder with a personal computer (PC) . Five fractions of the olfactory cell proteins gave 5 probes . The response of the nose was analyzed by the PC either as profiles to show the kinds of doors, or as scale factors to show the intensity of odours . Definite differences were noted between the profiles of the headspace gases from earlier and later stages of composing of solid hog wastes . The scale factors showed a single large peak in the earlier stage and one small peak in the later stage . The former showed vigorous biodegradation of organic matter and the latter indicated stabilization of the finished compost . In addition to its use in composing, the nose can discriminate various kinds of alcoholic beverages.

Biotechnol Adv, 1992, 10(2), 149 - 78
Evaluation of methods for detecting ecological effects from genetically engineered microorganisms and microbial pest control agents in terrestrial systems; Seidler RJ; This report summarizes and evaluates research from several laboratories that deals with the detection of ecological effects induced through exposure of microbes or plants to genetically engineered microorganisms (GEMs) and microbial pest control agents (MPCAs) . Some 27 potential endpoints for measuring effects have been studied . Perturbations induced by GEMs have been detected in about one-half of these endpoints . Detectable effects have been recorded for over half of the 16 species of bacteria and fungi studied . The effects caused by GEMs and MPCAs include inhibition of beneficial mycorrhizal fungi growing on Douglas fir seedling roots, depression in plant root and shoot growth, inhibition of predatory soil protozoa, accumulation of a toxic metabolite during biodegradation that inhibits soil fungi, increased microbial community respiration due to rapid lignin breakdown in soil, and the displacement of a broad group of gram-negative bacteria that inhabit the root surface of cereal crops . These effects were usually, but not always, of short duration . However, some of the changes were irreversible during the observation time of days, weeks, or in one case, months.

Biotechnol Adv, 1996, 14(1), 35 - 56
Biodegradation of chlorinated phenolic compounds; Annachhatre AP et al.; Chlorophenolic compounds are generated from a number of industrial manufacturing processes including pulp and paper manufacture . These compounds are found to be toxic and recalcitrant and hence their discharge into the environment must be regulated . Slow and partial degradation of chlorophenols under aerobic and anaerobic natural environment has been observed . Aerobic biodegradation of chlorophenols proceeds through the formation of catechols while under anaerobic conditions, reductive dehalogenation is the preferred metabolic pathway . Number and position of chlorine substituents on the phenolic ring has influence on the rate and extent of biodegradation of chlorophenols . In engineered systems, acclimatization of biomass to chlorophenols markedly enhances the biodegradation ability by reducing the initial lag phase and by countering inhibition . Partial removal of chlorophenols between 40-60% is usually observed in aerobic and anaerobic processes . Removal can be enhanced by a combination of aerobic and anaerobic operations.

Environ Sci Pollut Res Int, 2003, 10(5), 308 - 16
Biodegradation of anthracene in the roots and growth substrate of poplar cuttings; Ballach HJ et al.; Following their exposure to anthracene, the roots of Populus nigra L . Loenen showed traces of 9 substances classed as products of biodegradation . The main substances detected were phthalic acid and 9,10-anthraquinone, followed by hydroxyanthracene and methoxyanthracene and five other compounds which could not be identified . Due to the relatively low concentration of degradation products found in the roots, further degradation to lower molecular compounds are discussed . The presence of 9,10-anthraquinone as the main product of the degradation of anthracene was also evident in the control tests with unplanted sandy substrate, although the content was higher in the planted series of tests . As a non-sterile approach was chosen, it may be assumed that a microbial degradation for 9,10-anthraquinone took place in the control series . However, it is difficult to differentiate clearly between a microbial degradation of anthracene in the substrate and metabolization in the roots due in part to the absence of specific degradation products in the various reaction areas.

Environ Sci Pollut Res Int, 2003, 10(5), 287 - 95
Environmental impacts of coastal aquaculture in eastern Mediterranean bays: the case of Astakos Gulf, Greece; Belias CV et al.; GOAL, SCOPE AND BACKGROUND: Over the last decade Greece has become a leading country in the EU as concerns the cage farming of seabream and seabass . A strong debate has risen, however, about the environmental impacts of aquacultures in the coastal areas . The present paper deals with this problem and it is based on measurements of physico-chemical parameters in the water column, particulate matter and sediments in the area of Astakos Gulf, a coastal embayment in western Greece where three big fish farms are currently operating . METHODS: Water samples were collected by using Hydro-Bios sampling bottles, whereas a prototype sediment trap was installed under a fish cage for the collection of particulate matter . Temperature, dissolved oxygen, pH and salinity were measured in situ using portable equipment . Nutrients were determined by standard spectrophotometric methods . Trace metals were determined by Atomic Absorption Spectrometry . Dissolved organic carbon was determined by a Shimadzu 5000A carbon analyzer, whereas organic carbon in sediments was determined titrimetrically . RESULTS AND DISCUSSION: No clear eutrophication incidents have been identified, although the water column near the fish farms was enriched in nutrients and organic carbon . A sludge 'blanket' covers considerable parts of the seabed and is enriched in colloidal organic carbon and trace metals (Cd, Cu, Fe and Zn) that come from unused fish food . The biodegradation of this sludge leads to the development of anoxic conditions followed by the formation of undesirable gases, precipitation or remobilization of metals and the extinction of benthic fauna . CONCLUSION: The operation of fish farms at the coastal area of Astakos Gulf, and probably in similar Mediterranean gulfs, affects the marine environment, particularly in the vicinity of the cages . The most significant influence concerns the near-bottom water layer . The environmental impacts depend on the amount of food given to fishes, the mode of feeding, the fish density in cages, the annual production and the years of unit operation . The hydrology and the geomorphology of the area are also critical factors for its environmental quality . RECOMMENDATION AND OUTLOOK: The success of the fish-farming sector in the Mediterranean is accompanied by environmental and, in some extents, by social and marketing problems . These problems, derived from the rapid development of fish farming, can be solved only through an integrated management, using methods such as environmental impact assessment, risk assessment, economic evaluation, vulnerability assessments, resource accounting, cost-benefit analysis and outcome-based monitoring.

J Biomater Sci Polym Ed, 2003, 14(8), 837 - 49
Biodegradation of a dental composite by esterases: dependence on enzyme concentration and specificity; Finer Y et al.; Studies have shown that inflammatory (cholesterol esterase, CE) and salivary (pseudo-cholinesterase, PCE) enzymes can cause the breakdown of bisphenol-A diglycidyl dimethacrylate (bisGMA) and triethylene glycol dimethacrylate (TEGDMA) components from composite resins . Based on the above consideration, it was desired to show how CE- and PCE-catalyzed hydrolysis of resin components was dependent on the enzymes' concentration and to determine their distinct specificities (if any) towards resin components . Photopolymerized model composite resin samples (60% weight fraction silanated barium glass filler) based on bisGMA and TEGDMA monomers (55/45 weight ratio of the matrix, respectively) were incubated with PBS and either 0.01, 0.05, 0.1 or 1 unit/ml of CE or PCE for 16 days (pH 7.0, 37 degrees C) . Incubation solutions were analyzed by high-performance liquid chromatography (HPLC), UV spectroscopy and mass spectrometry . The composite samples were characterized by scanning electron microscopy (SEM) . Degradation rates of bisGMA and TEGDMA monomers were assessed . The results showed that CE had a greater specificity towards cleaving bisGMA while PCE showed a greater specificity towards TEGDMA . A strong enzyme concentration dependence was observed which suggests that the level of degradation products generated for a material will depend on the esterase make-up of an individual's saliva in combination with the specific formulation of monomer components used.

Water Sci Technol, 2003, 48(4), 221 - 7
Experimental investigation and modelling of the effect of sulfate on anaerobic biodegradation processes in municipal solid waste; Mora-Naranjo N et al.; The experimental investigations have been carried out in two parts . First, the biodegradation of the organic compounds in the municipal solid waste has been investigated with focus on different sulfate concentrations influencing the methane formation . Second, the inhibition effect of hydrogen sulfide in solution (H2S(aq)) on the acetate, and methane formation, respectively, has been studied at different pH and temperature values . In solution the equilibrium of hydrogen sulfide (H2S(aq)) and the hydrogen sulfide anion (HS-(aq)) mainly depends on pH . At pH 6.3 the favoured species is H2S(aq) whereas at pH 7.7 the HS-(aq) species is favoured . Additionally, the experiments have been carried out at two different temperatures (35 degrees C and 55 degrees C) . According to the acetate and methane formation the H2S(aq) species is observed to have an inhibitory effect . All simulations based on a biodegradation model represented are in good agreement with the experimental data obtained.

Biomaterials, 2003 Nov, 24(26), 4833 - 41
Collagen/chitosan porous scaffolds with improved biostability for skin tissue engineering; Ma L et al.; Porous scaffolds for skin tissue engineering were fabricated by freeze-drying the mixture of collagen and chitosan solutions . Glutaraldehyde (GA) was used to treat the scaffolds to improve their biostability . Confocal laser scanning microscopy observation confirmed the even distribution of these two constituent materials in the scaffold . The GA concentrations have a slight effect on the cross-section morphology and the swelling ratios of the cross-linked scaffolds . The collagenase digestion test proved that the presence of chitosan can obviously improve the biostability of the collagen/chitosan scaffold under the GA treatment, where chitosan might function as a cross-linking bridge . A detail investigation found that a steady increase of the biostability of the collagen/chitosan scaffold was achieved when GA concentration was lower than 0.1%, then was less influenced at a still higher GA concentration up to 0.25% . In vitro culture of human dermal fibroblasts proved that the GA-treated scaffold could retain the original good cytocompatibility of collagen to effectively accelerate cell infiltration and proliferation . In vivo animal tests further revealed that the scaffold could sufficiently support and accelerate the fibroblasts infiltration from the surrounding tissue . Immunohistochemistry analysis of the scaffold embedded for 28 days indicated that the biodegradation of the 0.25% GA-treated scaffold is a long-term process . All these results suggest that collagen/chitosan scaffold cross-linked by GA is a potential candidate for dermal equivalent with enhanced biostability and good biocompatibility.

Transplant Proc, 2003 Sep, 35(6), 2186 - 9
Plasma adiponectin concentration before and after successful kidney transplantation; Chudek J et al.; BACKGROUND: Adiponectin, a protein secreted exclusively by adipocytes, is presumed to be involved in the pathogenesis of atherosclerosis and insulin resistance . An elevated plasma adiponectin concentration was found in ESRD patients on hemodialysis (HD) . However, the role of kidneys in adiponectin biodegradation/elimination is unknown . Therefore, we assessed plasma adiponectin concentrations in ESRD patients before and after successful kidney transplantation . METHODS: Among 44 hemodialyzed patients (29 men, 15 women; mean age 39 +/- 11 years; mean body mass index {BMI} 23.6 +/- 3.5 kg/m(2); mean duration of HD treatment before kidney transplantation 27 +/- 26 months), plasma adiponectin concentrations and insulin resistance indices (HOMA-R) were measured twice: immediately before kidney transplantation (Tx) and 1-2 days before patient discharge from the hospital with stable kidney transplant function (mean serum creatinine level 191 +/- 105 micromol/L) . The control group consisted of 22 normotensive healthy subjects (12 men, 10 women) . RESULTS: Among uremic patients, before Tx, plasma adiponectin concentrations were significantly higher than in healthy subjects (20.8 +/- 8.3 vs 8.7 +/- 4.8 microg/mL; P <.001) After successful Tx, plasma adiponectin concentrations decreased significantly (20.8 +/- 8.3 vs 15.7 +/- 7.0 microg/mL before and after Tx, respectively; P <.001) . Simultaneously, after successful kidney transplantation, an increase in HOMA-R was observed (1.01 +/- 0.61 vs 1.43 +/- 0.83; P =.002) . However, changes in adiponectinemia did not significantly correlate with serum creatinine or HOMA-R . CONCLUSION: The kidneys seem to play an important role in adiponectin biodegradation and/or elimination.

Environ Sci Technol, 2003 Sep 15, 37(18), 4205 - 12
Isotopic and geochemical assessment of in situ biodegradation of chlorinated hydrocarbons; Kirtland BC et al.; Currently there is no in situ method to detect and quantify complete mineralization of chlorinated hydrocarbons (CHCs) to CO2 . Combined isotopic measurements in conjunction with traditional chemical techniques were used to assess in situ biodegradation of trichloroethylene (TCE) and carbon tetrachloride (CT) . Vadose zone CHC, ethene, ethane, methane, O2, and CO2 concentrations were analyzed using gas chromatography over 114 days at the Savannah River Site . delta13C of CHC and delta13C and 14C of vadose zone CO2, sediment organic matter, and groundwater dissolved inorganic carbon (DIC)were measured . Intermediate metabolites of TCE and CT accounted for < or = 10% of total CHCs . Delta13C of cis-1,2-dichloroethylene (DCE) was always heavier than TCE indicating substantial DCE biodegradation . 14C-CO2 values ranged from 84 to 128 percent modern carbon (pMC), suggesting that plant root-respired CO2 was dominant . 14C-CO2 values decreased over time (up to 12 pMC), and contaminated groundwater 14C-DIC (76 pMC) was substantially depleted relative to the control (121 pMC) . 14C provided a direct measure of complete CHC mineralization in vadose zone and groundwater in situ and may improve remediation strategies.

Waste Manag, 2003, 23(8), 719 - 28
Environmental impact of highway construction and repair materials on surface and ground waters . Case study: crumb rubber asphalt concrete; Azizian MF et al.; The practice of incorporating certain waste products into highway construction and repair materials (CRMs) has become more popular . These practices have prompted the National Academy of Science, National Cooperative Highway Research Program (NCHRP) to research the possible impacts of these CRMs on the quality of surface and ground waters . State department of transportations (DOTs) are currently experimenting with use of ground tire rubber ( crumb rubber) in bituminous construction and as a crack sealer . Crumb rubber asphalt concrete (CR-AC) leachates contain a mixture of organic and metallic contaminants . Benzothiazole and 2(3H)-benzothiazolone (organic compounds used in tire rubber manufacturing) and the metals mercury and aluminum were leached in potentially harmful concentrations (exceeding toxic concentrations for aquatic toxicity tests) . CR-AC leachate exhibited moderate to high toxicity for algae ( Selenastrum capriconutum) and moderate toxicity for water fleas ( Daphnia magna) . Benzothiazole was readily removed from CR-AC leachate by the environmental processes of soil sorption, volatilization, and biodegradation . Metals, which do not volatilize or photochemically or biologically degrade, were removed from the leachate by soil sorption . Contaminants from CR-AC leachates are thus degraded or retarded in their transport through nearby soils and ground waters.

Prikl Biokhim Mikrobiol, 2003 Jul-Aug, 39(4), 441 - 5
{Phytotoxic activity of chernozem saprophytic micromycetes: specificity, sorption and stability of phytotoxins in soil}; Svistova ID et al.; Micromycetes of the complex of typical chernozem saprotrophic fungi released phytotoxic metabolites into medium . The metabolites displayed their phytotoxic activities directly in soil . Evaluation of the toxicities, range of biological effects activities, and stabilities of phytotoxins in soil and the rates of their biodegradation allowed the species that can serve as indicators of chernozem microbial toxicosis to be selected, namely, Aspergillus clavatus, Fusarium solani, Talaromyces flavus, Penicillium rubrum, and P . funiculosum.

J Contam Hydrol, 2003 Oct, 66(1-2), 93 - 115
Biodegradation of petroleum hydrocarbon vapors: laboratory studies on rates and kinetics in unsaturated alluvial sand; Hohener P et al.; Predictions of natural attenuation of volatile organic compounds (VOCs) in the unsaturated zone rely critically on information about microbial biodegradation kinetics . This study aims at determining kinetic rate laws for the aerobic biodegradation of a mixture of 12 volatile petroleum hydrocarbons and methyl tert-butyl ether (MTBE) in unsaturated alluvial sand . Laboratory column and batch experiments were performed at room temperature under aerobic conditions, and a reactive transport model for VOC vapors in soil gas coupled to Monod-type degradation kinetics was used for data interpretation . In the column experiment, an acclimatization of 23 days took place before steady-state diffusive vapor transport through the horizontal column was achieved . Monod kinetic parameters Ks and vmax could be derived from the concentration profiles of toluene, m-xylene, n-octane, and n-hexane, because substrate saturation was approached with these compounds under the experimental conditions . The removal of cyclic alkanes, isooctane, and 1,2,4-trimethylbenzene followed first-order kinetics over the whole concentration range applied . MTBE, n-pentane, and chlorofluorocarbons (CFCs) were not visibly degraded . Batch experiments suggested first-order disappearance rate laws for all VOCs except n-octane, which decreased following zero-order kinetics in live batch experiments . For many compounds including MTBE, disappearance rates in abiotic batch experiments were as high as in live batches indicating sorption . It was concluded that the column approach is preferable for determining biodegradation rate parameters to be used in risk assessment models.

Bioprocess Biosyst Eng, 2003 Nov, 26(1), 37 - 48 Epub 2003 Sep 25.
On-line estimation of biodegradation in an unsaturated soil; Schoefs O et al.; The objective of this study was to develop a model-based estimator of biodegradation in unsaturated soil . This would allow real-time assessment of the efficiency of treatment bioprocesses, such as bioventilation and biopile, and eventually permit optimization through the implementation of control strategies . Based on a reduced-order model, an asymptotic observer was designed to estimate on-line the contaminant concentration, using carbon dioxide measurement . Two observer-based estimators were built to approximate: (1) the specific microbial growth rate; and (2) the biocontact kinetics representing the soil resistance to contaminant biodegradation . State observers and parameter estimators were confronted with the experimental results of biodegradation in microcosms . Hexadecane was used as the model compound, representing petroleum hydrocarbons . Three water contents, corresponding to 20%, 50% and 80% of the water-holding capacity, were tested . The asymptotic observer is able to predict hexadecane depletion with an error on the overall time trajectories of 13%, 8% and 4% for the dry, intermediate and wet soils, respectively, which is acceptable given that all the biokinetic parameters were identified from a biodegradation experiment in liquid phase . The observer-based estimator of the specific microbial growth rate, based on the CO(2) measurement, was successfully calibrated using the off-line measurements of hexadecane as validation data, and allowed estimation of the time when biodegradation switched from a microbial to a biocontact limitation . The biocontact kinetics was also identified on-line, using an estimator based on the hexadecane not in biocontact . These results are very encouraging with respect to the potential for on-line assessment of the performance of treatment bioprocesses in unsaturated soils.

Environ Microbiol, 2003 Oct, 5(10), 1002 - 8
A strain isolated from gas oil-contaminated soil displays chemotaxis towards gas oil and hexadecane; Lanfranconi MP et al.; In this report we describe the isolation of a strain from soil contaminated with gas oil by taking bacteria from a chemotactic ring on gas oil-containing soft agar plates . Partial 16 S rDNA sequencing of the isolated strain showed 99.1% identity with Flavimonas oryzihabitans . It was not only able to degrade different aliphatic hydrocarbons but it was also chemotactic towards gas oil and hexadecane, as demonstrated by the use of three different chemotaxis methods, such as agarose plug and capillary assays and swarm plate analysis . In addition, the strain was chemotactic to a variety of carbon sources that serve as growth substrates, including glucose, arabinose, mannitol, glycerol, gluconate, acetate, succinate, citrate, malate, lactate and casaminoacids . This is the first report on chemotaxis of a hydrocarbon-degrading bacterium towards a pure alkane, such as hexadecane . The fact that environmental isolates show chemotaxis towards contaminant/s present in the site of isolation suggests that chemotaxis might enhance biodegradation by favouring contact between the degrading microorganism and its substrate.

Environ Microbiol, 2003 Oct, 5(10), 944 - 53
A novel pathway for mineralization of the thiocarbamate herbicide molinate by a defined bacterial mixed culture; Barreiros L et al.; A bacterial mixed culture able to mineralize molinate was established, through enrichment, using mineral medium with molinate as the only carbon, nitrogen and energy source . The combination of five cultivable isolates, purified from the enrichment culture, permitted the reconstitution of a degrading consortium . Both enrichment and defined cultures were able to mineralize molinate without accumulation of degradation products by the end of the growth . Among the five isolates constituting the defined mixed culture, an actinomycete, strain ON4, was essential for biodegradation, being involved in the cleavage of the thioester bond of molinate, the initial step of the degradation pathway . Isolate ON4 was able to grow on molinate at concentrations below 2 mM, with the accumulation of ethanethiol and diethyl disulphide . These sulphur compounds were toxic to strain ON4 when accumulating at higher concentrations . However, this inhibitory effect was avoided by the presence of other members of the mixed culture, out of which isolates ON1 and ON2 were observed to consume ethanethiol and diethyl disulphide . In this way, interactions among defined mixed culture members involve metabolic and detoxifying association.

Water Sci Technol, 2003, 48(2), 269 - 76
The reasons behind the performance superiority of a high rate algal pond over three facultative ponds in series; El Hamouri B et al.; Results from a tracer study were used to determine and to compare actual and standard (k(20 degrees C)) first order reaction rate constants for COD removal in a High Rate Algal Pond (HRAP) and in 3 facultative ponds (FP) in series . An annual average k(20 degreesC) of 0.123 day(-1) was found for the HRAP while the values of 0.097, 0.025 and 0.003 d(-1) were found for facultative ponds 1, 2 and 3 respectively . Also, comparing nominal and tracer study hydraulic retention times showed large differences for the FP but not for the HRAP indicating that the former were suffering from severe short-circuiting . Loading rate within the range of operation exhibited a positive correlation with k(20 degrees C) for the HRAP but did not show such a relationship for any of the FP . Optimal chlorophyll-a concentration was found to be 3 mg/l for the HRAP and only 1.1 mg/l for the FP . Pollutant specific removal rates (SRR), that translate the hydrodynamic efficiency and the rate of COD biodegradation into pond performance per m2 and per day were calculated . They show that the adoption of the HRAP in place of a series of 3 FP reduces the net land area requirement (LAR) by at least 40%.

Chemosphere, 2003 Dec, 53(8), 921 - 6
Ecotoxicity and biodegradation of phthalate monoesters; Scholz N; Little is known about the fate and the effects of phthalic acid monoesters . Various of these monoesters ranging from n-butyl to isononyl monoester have been evaluated in respect to their biodegradation behaviour and their acute aquatic toxicity . All esters are readily biodegradable, achieving degradation rates of 90% and more . The acute toxicity values strongly depend on the carbon chain length of the alcohol moiety . The short chain specimen have LC/EC50 around and above 100 mg/l, with values levelling off to around 30 mg/l for the isononyl monoester.

Indian J Environ Health, 2002 Jul, 44(3), 181 - 8
Experimental studies on waste paper pulp biodegradation; Sharma R et al.; In continuation of their studies on Biodegradation of cellulosic waste materials, the authors have presented their experimental data on biodegradation on waste paper pulp . Greater efficiency in the cow dung and M3 culture experimental setups have been pointed out and discussed . Necessity of detailed data evaluation of temperature, pH, dry weight, cellulose, protein, carbohydrate, Nitrate, Phosphate & Potassium levels is suggested . Derivation of %, absolute and increase/decrease % of BOO, COD and VS have been pointed out for the first time in solid waste Biodegradation . Further data evaluation and derivation of critical reaction rate kinetics have been recommended for further studies in solid waste-degradation to achieve quicker Bioconversion of cellulosic wastes into compost.

Eur J Pharm Sci, 2003 Sep, 20(1), 53 - 61
Study of the biodegradation and in vivo biocompatibility of novel biomaterials; Fulzele SV et al.; The degradation of two rosin-based biomaterials, the glycerol ester of maleic rosin (GMR) and the pentaerythritol ester of maleic rosin (PMR), was examined in vitro in phosphate-buffered saline at pH 7.4 and in vivo in a subcutaneous rat model . Free films of the two biomaterials with mean thickness 0.4+/-0.02 mm were used for the study . The initial biocompatibility was followed by microscopic examination of the inflammatory tissue response to the implanted films . Sample weight loss and molecular weight decline of the free films was used to monitor the degradation quantitatively, while surface morphological changes were analysed for qualitative estimation . Biocompatibility response was followed on post-operative days 7, 14, 21 and 28 and compared with those of poly(DL-lactic-co-glycolic acid) (PLGA) (50:50) films . Both biomaterials showed slow in vitro degradation when compared with the in vivo rate . The mechanism followed was, however, bulk degradation of the films . The penta-esterified form of maleic rosin was observed to degrade more rapidly than glycerol esterified maleic rosin . The acute and subacute inflammatory reactions were characterized by fibrosis at the end of 28 days . The biomaterials showed reasonable tissue tolerance to the extent evaluated . There was a total absence of tissue necrosis or abscess formation for all implanted films . The response, although not identical to that of PLGA, is reasonable, promising new drug delivery applications for rosin biomaterials.

Ground Water, 2003 Sep-Oct, 41(5), 682 - 9
Bacterial transport experiments in fractured crystalline bedrock; Becker MW et al.; The efficiency of contaminant biodegradation in ground water depends, in part, on the transport properties of the degrading bacteria . Few data exist concerning the transport of bacteria in saturated bedrock, particularly at the field scale . Bacteria and microsphere tracer experiments were conducted in a fractured crystalline bedrock under forced-gradient conditions over a distance of 36 m . Bacteria isolated from the local ground water were chosen on the basis of physicochemical and physiological differences (shape, cell-wall type, motility), and were differentially stained so that their transport behavior could be compared . No two bacterial strains transported in an identical manner, and microspheres produced distinctly different breakthrough curves than bacteria . Although there was insufficient control in this field experiment to completely separate the effects of bacteria shape, reaction to Gram staining, cell size, and motility on transport efficiency, it was observed that (1) the nonmotile, mutant strain exhibited better fractional recovery than the motile parent strain; (2) Gram-negative rod-shaped bacteria exhibited higher fractional recovery relative to the Gram-positive rod-shaped strain of similar size; and (3) coccoidal (spherical-shaped) bacteria transported better than all but one strain of the rod-shaped bacteria . The field experiment must be interpreted in the context of the specific bacterial strains and ground water environment in which they were conducted, but experimental results suggest that minor differences in the physical properties of bacteria can lead to major differences in transport behavior at the field scale.

Indian J Environ Health, 2002 Oct, 44(4), 266 - 9
Development of low cost all glass recirculation systems for environmental applications; Kshirsagar PS et al.; Some simple glassware has been developed for recirculation of liquid medium . These glassware have wider applications and have been tested in experiments involving leaching, biodegradation, and desulfurization . The fabrication cost is minimum and can be developed in a small glassware workshop . Such a development has certain advantages as no separate mechanical devices are needed, the flow can be easily monitored due to transparency of the apparatus, acidic or alkaline medium can also be circulated . The paper discusses the development, design and fabrication of some specialized glass recirculation systems and its environmental applications.

Int J Syst Evol Microbiol, 2003 Sep, 53(Pt 5), 1291 - 6
Pedobacter cryoconitis sp . nov., a facultative psychrophile from alpine glacier cryoconite; Margesin R et al.; On the basis of phenotypic and genotypic characteristics, a novel species belonging to the genus Pedobacter is described . A facultatively psychrophilic, Gram-negative, aerobic, rod-shaped strain, A37(T), was isolated from alpine glacier cryoconite . The non-flagellated and non-spore-forming isolate grew over a temperature range of 1-25 degrees C, showed activities of oxidase, catalase, DNase, protease (gelatin, casein), amylase, beta-glucosidase, beta-galactosidase and beta-lactamase and degraded oil hydrocarbons . A distinct optimum temperature of 15 degrees C was observed for both protease production and oil hydrocarbon biodegradation . Analysis of 16S rDNA revealed that strain A37(T) represents a distinct taxon within PEDOBACTER: DNA from strain A37(T) showed only 19.7 % genetic relatedness to the DNA of Pedobacter piscium . The DNA G+C content was 43.4 mol% . Dominant fatty acids (51 %) were iso-15 : 0 2-OH and 16 : 1omega7c . The strain is assigned to a novel Pedobacter species, for which the name Pedobacter cryoconitis sp . nov . is proposed, with A37(T) (=DSM 14825(T)=LMG 21415(T)) as the type strain.

J Environ Biol, 2003 Apr, 24(2), 181 - 6
Decolorization of anthraquinone dye by Aspergillus ficuum in various physiological states; Xinjiao D et al.; Decolorization of reactive brilliant blue KN-R by Aspergillus ficuum was investigated on suspended spores, mycelial pellets, immobilized cells . It was found that Aspergillus ficuum could effectively decolorize reactive brilliant blue KN-R especially when grown as pelleted mycelia . Many factors affecting the decolorization process in nitrogen-limited media (NLM) were studied, including: initial pH, temperature, and mycelial age . Results showed that the media containing reactive brilliant blue KN-R at 50 mg/L could be decolorized by 96% of the initial color in 42 h, in most conditions tested, the dye degraded products assayed by UV-visible spectrophotometer and macroscopic observation showed that the decolorization of reactive brilliant blue KN-R by mycelial pellets includes two important processes: biodegradation and biosorption . Kinetic study revealed that reactive brilliant KN-R biodegradation by mycelial pellets and suspended spores conformed to first-order reaction model while reactive brilliant blue KN-R biodegradation by immobilized cell followed zero-order model . In addition, mycelial pellets was found to biodegrade KN-R more quickly than suspended spores and immobilized cell.

Ying Yong Sheng Tai Xue Bao, 2003 Jun, 14(6), 1003 - 6
{Research advances in biodegradation of chlorophenols in environment}; Jiang M et al.; This paper examines the biodegradation of chlorophenols by microbes and deals with the chlorophenols-degrading microbes and the usage of biotechnology with special emphasis on degradation mechanisms . Dechlorination is the first critical step in the bacterial degradation of many chloroniated pollutans . Under aerobic condition, the degradation of mono- and dichlorophenols is shown to be initiated by oxygenation into chlorocatechols, and dechlorination occurs only after ring cleavage of the chlorocatechols . The degradation of polychlorinated phenols starts by hydrolytic para-hydroxylation, yielding chlorinated para-hydroquinone . The anaerobic biodegradation of chlorophenols occurs by reductive dechlorination, a process by which chlorines are replaced with hydrogen.

Spine, 2003 Sep 1, 28(17), 1954 - 60
Lumbar spinal fusion with a mineralized collagen matrix and rhBMP-2 in a rabbit model; Liao SS et al.; STUDY DESIGN: A new mineralized collagen matrix combined with or without growth factor was used for the posterolateral spinal fusion in the rabbit lumbar spine . OBJECTIVES: The availability of a new osteoconductive matrix with or without recombinant osteoinductive growth factors offers a possible alternative to the use of autogenous bone for grafting indications . This study evaluated the bone-forming activity of the biomimetic matrix: nano-hydroxyapatite/collagen/polylactic acid (nHAC/PLA) combined without or with recombinant human bone morphogenetic protein-2 (rhBMP-2) in a rabbit posterolateral spinal fusion . SUMMARY OF BACKGROUND DATA: Many bone grafting materials such as titanium alloy, ceramics, and polymers were used to repair bony defects . However, each has specific disadvantaged . The permanent implantation still has possibility to be eroded in vivo, which is caused by late breakdown and abscess formation . The acidic outcome of polymer biodegradation was also negatively affected in the later-stage results of bone repair . It needed a promising material for an alternative to the use of autogenous bone for grafting indications . MATERIALS AND METHODS: Sixty-four rabbits were randomly divided into four groups: autologous iliac crest bone group (ACB), nHAC/PLA composite group (nHAC/PLA), autologous iliac crest bone mixed with nHAC/PLA composite group (ACB + nHAC/PLA), nHAC/PLA composite with recombinant human BMP-2 group (nHAC/PLA + rhBMP-2) . The lumbar intertransverse process fusions were assessed by manual palpation, radiographic, histologic, and mechanical strength, and scanning electronic microscopy (SEM) in a 10-week observation . RESULTS: Optimal formulations of the ACB + nHAC/PLA and nHAC/PLA + rhBMP-2 groups were shown to perform similar to ACB in both the fusion ratio and mechanical strength in the 6 and 10 weeks after surgery . From the microstructure analysis of the samples, there was no negative effect when the compound implanted this composite with autogenous iliac crest, and there was also new bone-like tissue formation implanted this composite without combined rhBMP-2 early at the second week after surgery . CONCLUSIONS: This study shows the effective results of nHAC/PLA in rabbit posterolateral spinal fusion combined with rhBMP-2 . It is an alternative method to autograft by compounding this osteoconductive matrix with growth factors.

J Hazard Mater, 2003 Aug 29, 102(2-3), 243 - 55
Anaerobic treatability of high oil and grease rendering wastewater; Nakhla G et al.; This study evaluated the use of a new biosurfactant, BOD-Balance, derived from cactus for the treatment of oil-and-grease-laden rendering wastewater anaerobically . Batch laboratory experimental results and preliminary full-scale data are presented . The biosurfactant affected a significant increase in the COD degradation rate for the raw wastewater . However, after reduction of the oil and grease (O&G) by dissolved air flotation, the biosurfactant did not exhibit any advantages . Modeling of the data indicated that various COD fractions, i.e . both soluble and particulate as well as total COD at various testing conditions conformed well to both zero-order and first-order models . The biosurfactant affected a 164-238 and 164-247% increase in COD and particulate COD biodegradation rate for the raw wastewater . The reduction of O&G concentration to <800 mg/l increased total and soluble COD degradation rates by 106% . Results from the full-scale mesophilic anaerobic digestion system indicated that the addition of the biosurfactant at doses of 130-200 mg/l decreased O&G concentrations from 66,300 to 10,200 mg/l over a 2-month-period.

Indian J Environ Health, 2002 Jan, 44(1), 8 - 11
Biodegradation of p-nitrophenol in anaerobic fixed film fixed bed reactor; Swaminathan K et al.; Biodegradation of p-nitrophenol (PNP) was studied in upflow anaerobic fixed film fixed bed reactor . The studies showed that PNP was not degraded as a sole carbon source in the reactor . Addition of glucose as co-substrate increased the degradation of PNP . A ratio of > 1 in terms of glucose to PNP could achieve 90% PNP degradation . However the total organic carbon (TOC) removals were 76.3% indicating the possibility of biotransformation of PNP.

Environ Sci Technol, 2003 Aug 1, 37(15), 3382 - 91
Soil column evaluation of factors controlling biodegradation of DNT in the vadose zone; Fortner JD et al.; High concentrations of 2,4-dinitrotoluene (2,4-DNT) and 2,6-dinitrotoluene (2,6-DNT) are present in vadose zone soils at many facilities where explosives manufacturing has taken place . Both DNT isomers can be biodegraded under aerobic conditions, but rates of intrinsic biodegradation observed in vadose zone soils are not appreciable . Studies presented herein demonstrate that nutrient limitations control the onset of rapid 2,4-DNT biodegradation in such soils . In column studies conducted at field capacity, high levels of 2,4-DNT biodegradation were rapidly stimulated by the addition of a complete mineral medium but not by bicarbonate-buffered distilled deionized water or by phosphate-amended tap water . Biodegradation of 2,6-DNT was not observed under any conditions . Microcosm studies using a DNT-degrading culture from column effluent suggest that, after the onset of 2,4-DNT degradation, nitrite evolution will eventually control the extent of degradation achieved by two mechanisms . First, high levels of nitrite (40 mM) were found to strongly inhibit 2,4-DNT degradation . Second, nitrite production reduces the solution pH, and at pH levels below 6.0, 2,4-DNT degradation slows rapidly . Under conditions evaluated in laboratory-scale studies, 2,4-DNT biodegradation enhanced the rate of contaminant loss from the vadose zone by a factor of 10 when compared to the washout due to leaching.

Biomed Environ Sci, 2003 Jun, 16(2), 126 - 32
Comparison of di-n-methyl phthalate biodegradation by free and immobilized microbial cells; Wang JL et al.; OBJECTIVE: To compare the biodegradation of di-n-methyl pathalate by free and immobilized microbial cells . METHODS: The enrichment and isolation technique was used to isolate the microorganism . The PAV-entrapment method was utilized to immobilize the microorganisms . The scanning electron microscophy (SEM) was used to observe the growth and distribution of microbial cells immobilized inside the PVA bead gels . The GC/MS method was used to identify the main intermediates of DMP degradation . RESULTS: The microbial cells could grow quite well in PVA gel . The metabolic pathway did not change before and after immobilization of the microbial cells . The degradation rate of immobilized cells was higher than that of free cells . CONCLUSION: The immobilized microbial cells possess advantages than free cells when applied to the biodegradation of toxic organic pollutants.

Chemosphere, 2003 Nov, 53(6), 609 - 18
Study of the biodegradation process of polychlorinated biphenyls in liquid medium and soil by a new isolated aerobic bacterium (Janibacter sp.); Sierra I et al.; We have isolated and characterised a novel aerobic bacterial strain, designated MS3-02, belonging to the genus Janibacter sp . The capability of this new strain to degrade polychlorinated biphenyls (PCBs) in a commercial mixture (Aroclor 1242) in liquid medium and in soil (sterile and non sterile soil), under laboratory scale, has been evaluated . MS3-02 was isolated from the soil around of an incinerator, located in the east of Madrid (Spain) . Gas-chromatographic analysis showed that MS3-02 was able to reduce most peaks observed in the chromatogram between 70% and 100% after seven days of incubation in a culture mineral medium containing yeast extract, but without the addition of biphenyl . The presence of biphenyl in the culture medium decreased the rate of PCB degradation by this bacterium . Comparing the performance of the MS3-02 in liquid culture medium and in soil, degradation was less efficient in sterile soil and still less efficient in non sterile soil . Under the best conditions (sterile soil and 20 weeks of incubation) MS3-02 was able to reduce, between 50% and 100%, nine of the main gas-chromatographic peaks in Aroclor 1242.

Biomacromolecules, 2003 Sep-Oct, 4(5), 1285 - 92
Biochemical and molecular characterization of poly(aspartic acid) hydrolase-2 from sphingomonas sp . KT-1; Hiraishi T et al.; Poly(aspartic acid) (PAA) hydrolase-2 was purified from crude soluble cellular extracts of Sphingomonas sp . KT-1 (JCM10459) and characterized to elucidate the mechanism of alpha,beta-poly(d,l-aspartic acid) (tPAA) biodegradation . The molecular mass of PAA hydrolase-2 was 42 kDa, and the isoelectric point was 9.6 . The optimum values of pH and temperature for the hydrolysis of alpha-di(l-aspartic acid) by PAA hydrolase-2 were 7.0 and 55 degrees C, respectively . The effect of inhibitors on the hydrolysis of alpha-di(l-aspartic acid) showed that the activity of PAA hydrolase-2 was significantly inhibited by EDTA . Thermally synthesized tPAA was hydrolyzed in the presence of two enzymes, PAA hydrolase-1 and PAA hydrolase-2, to generate aspartic acid . The PAA hydrolase-2 was capable of hydrolyzing alpha-poly(l-aspartic acid) of high molecular weights but had limited activity for tPAA . These results lead us to propose the following mechanism . First, PAA hydrolase-1 hydrolyzes tPAA to yield oligo(aspartic acid) via an endo-mode cleavage, and subsequently, PAA hydrolase-2 hydrolyzes the resultant oligo(aspartic acid) to yield aspartic acid . Analysis of hydrolyzed products from alpha- and beta-penta(l-aspartic acid) revealed that PAA hydrolase-2 catalyzed the exo-mode hydrolysis of alpha- and beta-penta (l-aspartic acid) . The gene encoding PAA hydrolase-2 from Sphingomonas sp . KT-1 was cloned, and genetic analysis showed that the deduced amino acid sequence of PAA hydrolase-2 is similar to a putative peptidase, which belongs to the M20/M25/M40 family of proteins, from Caulobacter crescentus CB15.

Environ Toxicol Chem, 2003 Sep, 22(9), 2013 - 9
Sequential bio- and phototransformation of the herbicide methabenzthiazuron in water; Malouki MA et al.; We investigated the transformation of methabenzthiazuron in water by microorganisms and solar light . This compound was very slowly phototransformed when irradiated at lambda > 290 nm, but it could be successfully oxidized into 6-hydroxymethabenzthiazuron by Aspergillus niger, as shown by nuclear magnetic resonance experiments . The toxicity of this metabolite, as determined by the standardized Microtox test, was sixfold lower than that of the parent molecule . The 6-hydroxymethabenzthiazuron was not further metabolized by A . niger but was photooxidized with ring cleavage of the aromatic ring and photodimerized on irradiation at lambda > 290 nm . In the presence of humic substances, the photodegradation was slower . We demonstrate that the transformations of methabenzthiazuron, observed either with the fungus A . niger or by the action of solar light, do not proceed via the urea chain N-dealkylation, as usually reported, but only via hydroxylation or cleavage of the benzene ring . This work shows the complementarity of both approaches, photo- and biodegradation, to study the fate of herbicides in the environment.

Appl Environ Microbiol, 2003 Sep, 69(9), 5198 - 206
Effects of soil pH on the biodegradation of chlorpyrifos and isolation of a chlorpyrifos-degrading bacterium; Singh BK et al.; We examined the role of microorganisms in the degradation of the organophosphate insecticide chlorpyrifos in soils from the United Kingdom and Australia . The kinetics of degradation in five United Kingdom soils varying in pH from 4.7 to 8.4 suggested that dissipation of chlorpyrifos was mediated by the cometabolic activities of the soil microorganisms . Repeated application of chlorpyrifos to these soils did not result in the development of a microbial population with an enhanced ability to degrade the pesticide . A robust bacterial population that utilized chlorpyrifos as a source of carbon was detected in an Australian soil . The enhanced ability to degrade chlorpyrifos in the Australian soil was successfully transferred to the five United Kingdom soils . Only soils with a pH of >/=6.7 were able to maintain this degrading ability 90 days after inoculation . Transfer and proliferation of degrading microorganisms from the Australian soil to the United Kingdom soils was monitored by molecular fingerprinting of bacterial 16S rRNA genes by PCR-denaturing gradient gel electrophoresis (DGGE) . Two bands were found to be associated with enhanced degradation of chlorpyrifos . Band 1 had sequence similarity to enterics and their relatives, while band 2 had sequence similarity to strains of Pseudomonas . Liquid enrichment culture using the Australian soil as the source of the inoculum led to the isolation of a chlorpyrifos-degrading bacterium . This strain had a 16S rRNA gene with a sequence identical to that of band 1 in the DGGE profile of the Australian soil . DNA probing indicated that genes similar to known organophosphate-degrading (opd) genes were present in the United Kingdom soils . However, no DNA hybridization signal was detected for the Australian soil or the isolated degrader . This indicates that unrelated genes were present in both the Australian soil and the chlorpyrifos-degrading isolate . These results are consistent with our observations that degradation of chlorpyrifos in these systems was unusual, as it was growth linked and involved complete mineralization . As the 16S rRNA gene of the isolate matched a visible DGGE band from the Australian soil, the isolate is likely to be both prominent and involved in the degradation of chlorpyrifos in this soil.

Chemosphere, 2003 Nov, 53(5), 539 - 49
Enantioselective biodegradation of mecoprop in aerobic and anaerobic microcosms; Harrison I et al.; Natural attenuation of mecoprop has been studied by determining changes in enantiomeric fraction in different redox environments down gradient from a landfill in the Lincolnshire limestone . Such changes could be due to differential metabolism of the enantiomers, or enantiomeric inversion . In order to confirm the processes occurring in the field, microcosm experiments were undertaken using limestone acclimatised in different redox zones . No biodegradation was observed in the methanogenic, sulphate-reducing or iron-reducing microcosms . In the nitrate-reducing microcosm (S)-mecoprop did not degrade but (R)-mecoprop degraded with zero order kinetics at 0.65 mg l(-1)day(-1) to produce a stoichiometric equivalent amount of 4-chloro-2-methylphenol . This metabolite only degraded when the (R)-mecoprop disappeared . In aerobic conditions (S)- and (R)-mecoprop degraded with zero order kinetics at rates of 1.90 and 1.32 mg l(-1)day(-1) respectively . The addition of nitrate to dormant iron-reducing microcosms devoid of nitrate stimulated anaerobic degradation of (R)-mecoprop after a lag period of about 20 days and was associated with the production of 4-chloro-2-methylphenol . Nitrate addition to sulphate-reducing/methanogenic microcosms did not stimulate mecoprop degradation . However, the added nitrate was completely utilised in oxidising sulphide to sulphate . There was no evidence for enantiomeric inversion . The study reveals new evidence for fast enantioselective degradation of (R)-mecoprop under nitrate-reducing conditions.

Anal Chem, 2003 Jun 1, 75(11), 2584 - 90
Development of a rapid ferricyanide mediated assay for biochemical oxygen demand using a mixed microbial consortium; Catterall K et al.; Ferricyanide-mediated (FM) microbial reactions were used for the rapid determination of the biochemical oxygen demand (BOD) of a range of synthetic and real wastewater samples . Four single-species microbial seeds and a synthetically prepared microbial consortium were compared . In all cases, the microbial consortium exhibited a greater extent and rate of biodegradation compared to the individual microbial seeds . Markedly improved correlation to the standard BOD5 method was also noted for the microbial consortium (compared to the single-species seeds) . A linear dynamic range up to 200 mg BOD5 L(-1) was observed, which is considerably greater than the linear range of the standard BOD5 assay and most other rapid BOD assays reported . In addition, biodegradation efficiencies comparable to the 5-day BOD5 assay (and much greater than other rapid BOD assays) were observed in 3 h . A highly significant correlation (R = 0.935, p = 0.000, n = 30) between the FM-BOD method and the standard BOD5 method was found for a wide diversity of real wastewater samples . The results indicate that the FM-BOD assay is a promising, rapid, alternative to the standard 5-day BOD5 assay.

Biodegradation, 2003 Aug, 14(4), 275 - 83
Biodegradation of cis-1,2-dichloroethylene and vinyl chloride in anaerobic cultures enriched from landfill leachate sediment under Fe(III)-reducing conditions; Hata J et al.; An anaerobic, Fe(III)-reducing enrichment culture, which originated from a sediment sample collected at a landfill in Nanji-do, Seoul, Korea, was capable of degrading cis-1,2-dichloroethylene (cis-DCE) and vinyl chloride (VC) . Although it exhibited the ability under Fe(III)-reducing conditions, the chlorinated ethenes degradation was not linked to the Fe(III) reduction . During cis-DCE degradation, no VC, ethene, or ethane was detected through the experimental period . Also, this culture did not accumulate ethene and ethane during the VC degradation . It was unlikely that cis-DCE was reductively dechlorinated to VC and then the VC formed was dechlorinated fast enough . Because the kinetic data showed that the rate of cis-DCE degradation was 3.5 times higher than that of VC . Whereas glucose supported the culture growth and the degradation, formate, acetate, butyrate, propionate, lactate, pyruvate, and yeast extract did not . The results appeared consistent with the involvement of oxidative degradation mechanism rather than reductive dechlorination mechanism . The traits of the culture described here are unusual in the anaerobic degradation of chlorinated ethenes and may be useful for searching an effective organism and mechanism regarding anaerobic cis-DCE and VC degradation.

Biodegradation, 2003 Aug, 14(4), 249 - 63
Biodegradation of selected UV-irradiated and non-irradiated polycyclic aromatic hydrocarbons (PAHs); Lehto KM et al.; Biodegradation of UV-irradiated anthracene, pyrene, benz{a}anthracene, and dibenz{a,h}anthracene was compared to that of the non-irradiated samples, individually and in synthetic mixtures with enrichment cultures . Combined treatment was repeated for individual anthracene and for the PAH mixture with Sphingomonas sp . strain EPA 505 and Sphingomonas yanoikuyae . Enrichment culture studies were performed on the PAH mixtures in the presence of the main photoproduct of anthracene, pure 9,10-anthracenedione . Photochemically pretreated creosote solutions were also subjected to biodegradation and the results were compared to those of the non-irradiated solutions . The primary interest was on 16 polycyclic aromatic hydrocarbons (PAHs) listed as priority pollutants by European Union (EU) and the United States Environmental Protection Agency (USEPA) . Irradiation accelerated the biodegradation onset for anthracene, pyrene, and benz{a}anthracene when they were treated individually . The biodegradation of irradiated pyrene started with no lag phase and was complete by 122 h whereas biodegradation of the non-irradiated sample had a lag of 280 h and resulted in complete degradation by 720 h . Biodegradation of PAHs was accelerated in synthetic mixtures, especially in the presence of pure 9,10-anthracenedione . In general, irradiation had no effect on the biodegradation of PAHs incubated in synthetic mixtures or with pure cultures . Under current experimental conditions, the UV-irradiation invariably reduced the biodegradation of PAHs in creosote . Based on the results of the present and previous photochemical-biological studies of PAHs, the influence of the photochemical pretreatment on the biodegradation is highly dependent on the compounds being treated and other process parameters.

Environ Sci Pollut Res Int, 2003, 10(4), 217 - 20
Photo-Fenton oxidation of oil mill waste water: chemical degradation and biodegradability increase; Canepa P et al.; The mill waste water holds a large amount of polyphenols, preventing the biodegradation processes because of their inhibitory action on microbial growth . Thus, its disposal represents an environmental problem for the great olive oil producing countries in the Mediterranean area . In this work, we present the preliminary results from the application of a photo-oxidative process on mill waste water to evaluate the organic matter degradation potential and the biodegradability of the treated residue . The total organic carbon is reduced up to 35% after 6 hours but the cost-effectiveness is unfavourable . In contrast, the aim of toxicity reduction is less expensive and shows good applicable chances; after 2 h, the polyphenols concentration drops by 60%.

Extremophiles, 2003 Dec, 7(6), 451 - 8 Epub 2003 Aug 26.
Hydrocarbon degradation and enzyme activities of cold-adapted bacteria and yeasts; Margesin R et al.; The potential of 89 culturable cold-adapted isolates from uncontaminated habitats, including 61 bacterial and 28 yeast strains, to utilize representative fractions of petroleum hydrocarbons (n-alkanes, monoaromatic and polycyclic aromatic hydrocarbons) for growth and to produce various enzymes at 10 degrees C was investigated . The efficiency of bacterial and yeast strains was compared . The growth temperature range of the yeast strains was significantly smaller than that of the bacterial strains . Sixty percent of the yeasts but only 8% of the bacteria could be classified as true psychrophiles, showing no growth above 20 degrees C . A high percentage (89%) of the yeast strains showed lipase activity . More than one-third of the 61 bacterial strains produced amylase, beta-lactamase, beta-galactosidase or lipase; more than two-thirds were protease producers . Only 6% of the bacterial strains but 79% of the yeast strains utilized n-hexadecane for growth; 13% of the bacterial strains and 21-32% of the yeast strains utilized phenol, phenanthrene or anthracene for growth . Only four yeast strains but none of the bacterial strains could grow with all hydrocarbons tested . The biodegradation of phenol was investigated in fed-batch cultures at 10 degrees C . Three yeast strains degraded phenol concentrations as high as 10 mM (one strain) or 12.5 mM (two strains) . Of eight bacterial strains, two strains degraded up to 10 mM phenol . The optimum temperature for phenol degradation was 20 degrees C for all eight bacterial strains and for two yeast strains . Biodegradation by five yeast strains was optimal at 10 degrees C and faster at 1 degrees C than at 20 degrees C . All phenol-degrading strains produced catechol 1,2 dioxygenase activity.

J Environ Sci (China), 2003 May, 15(3), 302 - 10
Phytoremediation and its models for organic contaminated soils; Gao YZ et al.; Soil pollution has been attracting considerable public attentions over the last decades . Sorts of traditional physiochemical methods have been used to remove the organic pollutants from soils . However, the enormous costs and low efficiencies associated with these remediation technologies limit their availabilities . Phytoremediation is an emerging technology that uses plants to cleanup pollutants in soils . As overwhelmingly positive results have been shown, phytoremediation is a most economical and effective remediation technique for organic contaminated soils . In this paper phytoremediation and its models for organic contaminated soils are viewed . The mechanisms of phytoremediation mainly include the direct plant uptake of organic pollutants, degradation by plant-derived degradative enzymes, and stimulated biodegradation in plant rhizosphere . Phytoremediation efficiency is close related to physicochemical properties of organic pollutants, environmental characteristics, and plant types . It is no doubt that soil amendments such as surfactants improves the solubilities and availabilities of organic pollutants in soils . However, little information is available about effects of soil amendments on phytoremediation efficiencies . Phytoremediation models have been developed to simulate and predict the environmental behavior of organic pollutants, and progress of models is illustrated . In many ways phytoremediation is still in its initial stage, and recommendations for the future research on phytoremediation are presented.

J Environ Qual, 2003 Jul-Aug, 32(4), 1244 - 9
RDX loss in a surface soil under saturated and well drained conditions; Ringelberg DB et al.; On military training ranges, low-order, incomplete detonations deposit RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine) into surface soils . In this study, we evaluated RDX biodegradation in surface soils obtained from a military training range in Alaska . Two factors were compared: (i) soil water potential during the incubations; and (ii) the use of acetonitrile (ACN) as an RDX carrier to spike samples . Organic solvents have been used in laboratory studies to dissolve slightly water-soluble contaminants before addition to soil . We added ACN to obtain final soil ACN concentrations of 0 mg kg(-1) (0%), 1000 mg kg(-1) (0.1%) and 10 000 mg kg(-1) (1%) . We then compared RDX attenuation in the soil under saturated and unsaturated conditions . RDX fell below the limit of detection within 3 wk of study initiation under the saturated condition . A maximum degradation rate of 0.15 mg RDX L(-1) d(-1) was measured . Under the unsaturated condition, 42% of the original RDX was still present at study termination (5 wk) . The addition of acetonitrile at 0.1 or 1.0% had no affect on RDX loss in the saturated soil . In the unsaturated soil, however, ACN at 1.0% inhibited RDX loss by as much as 25% . These findings indicate that soil water potential and carrier solvent concentrations can impact the rate and extent to which RDX is attenuated in a surface soil.

Int J Phytoremediation, 2003, 5(2), 125 - 36
A mathematical model of phytoremediation for petroleum contaminated soil: sensitivity analysis; Thoma GJ et al.; Phytoremediation is an attractive treatment technology for many contaminated sites due to its cost effectiveness and public acceptance . We present a sensitivity analysis of important parameters from a screening level model for phytoremediation by grass species of weathered petroleum-contaminated sites . The conceptual framework is that root movement through contaminated soil will enhance contaminant biodegradation by providing a local environment more favorable for petroleum degrading microorganisms--the so-called rhizosphere effect . Common questions in phytoremediation are, "What species should be planted?" and "What management practices should be followed?" These choices may affect degradation kinetics, root biomass (and therefore rhizosphere volume), and the root turnover . Important model parameters are the rate constants, rhizosphere volume, and the rate of root turnover . We present a sensitivity analysis with the aim of identifying the most important factors for improving phytoremediation effectiveness . For simulations of the phytoremediation of weathered diesel range organics, our results indicate that annual species, with higher root turnover, are preferred over perennial species with the caveat of equal degradation rate constants, that is, no species-dependent effects . In addition, the results suggest that the management of nonrhizosphere soil could play an important role in the overall effectiveness of phytoremediation . Finally, the effect of increasing root biomass or increasing the rhizosphere thickness is approximately equivalent with respect to the ultimate removal of the contaminants.

Water Sci Technol, 2003, 47(12), 231 - 8
Anaerobic degradation of organic materials--significance of the substrate surface area; Palmowski LM et al.; In anaerobic degradation of substrates containing mainly particulate organic matter, solids hydrolysis is rate-limiting . In these investigations, the particle size of various substrates was reduced by comminution to support hydrolysis . Two positive effects of comminution were observed . For substrates with high fibre content, which are particularly resistant to biodegradation, a significant improvement of the degradation degree was observed as a result of comminution . Secondly, for all substrates tested, and particularly for those rich in fibres, the degradation rate of comminuted samples was significantly higher . The first reason for both effects is an increase of the sample surface area . Several methods for measuring the specific surface area of organic materials, including particle size analysis, Nitrogen-adsorption and enzyme adsorption, were used and compared for the purpose of this study, where the surface area accessible to microbial enzymes is critical . The significance of the surface area in anaerobic degradation of particulate substrates was investigated through a kinetic model where the hydrolysis rate was based on the sample surface area . Good agreements were obtained between model and experiments carried out with samples of various specific surface areas . These results reinforced the significance of the sample area in anaerobic degradation processes . However, other effects of comminution responsible for the increased degradation degree and degradation rate were identified and discussed . These include: the increase of dissolved compounds due to cell rupture, exposition of surface areas previously inacessible for microbial degradation, and alteration of the sample structure such as the lignin-cellulose arrangements.

Environ Toxicol Chem, 2003 Aug, 22(8), 1710 - 23
Recent developments in broadly applicable structure-biodegradability relationships; Jaworska JS et al.; Biodegradation is one of the most important processes influencing concentration of a chemical substance after its release to the environment . It is the main process for removal of many chemicals from the environment and therefore is an important factor in risk assessments . This article reviews available methods and models for predicting biodegradability of organic chemicals from structure . The first section of the article briefly discusses current needs for biodegradability estimation methods related to new and existing chemicals and in the context of multimedia exposure models . Following sections include biodegradation test methods and endpoints used in modeling, with special attention given to the Japanese Ministry of International Trade and Industry test; a primer on modeling, describing the various approaches that have been used in the structure/biodegradability relationship work, and contrasting statistical and mechanistic approaches; and recent developments in structure/biodegradability relationships, divided into group contribution, chemometric, and artificial intelligence approaches.

Rev Argent Microbiol, 2003 Apr-Jun, 35(2), 62 - 8
{Biodegradability of the components of natural hydrocarbon mixtures previously submitted to landfarming}; Pucci GN et al.; The complex composition of the crude oil and the hydrocarbons that integrate the waste of the different stages of the oil industry turn this product a mixture that presents different difficulties for its elimination by biological methods . The objective of this paper was to study the biodegradation potential of autochthonous bacterial communities on hydrocarbons obtained from four polluted places and subjected to landfarming biorremediation system during a decade . The results showed a marked difference in biodegradability of the three main fractions of crude oil, aliphatic, aromatic, and polar fractions, obtained by column chromatography . All fractions were used as carbon source and energy . There were variations in the production of biomass among the different fractions as well as in the kinetics of biodegradation, according to the composition of each fraction.

Arch Microbiol, 2003 Oct, 180(4), 251 - 6 Epub 2003 Aug 15.
Culture conditions affecting biodegradation components of the brown-rot fungus Gloeophyllum trabeum; Varela E et al.; To determine the liquid culture conditions under which the wood-degrading system of the brown-rot fungus Gloeophyllum trabeum is expressed, enzymes and metabolites from liquid and solid substrate cultures were characterized . Enzymes were analyzed by 2-D gel electrophoresis and also assayed . Growth conditions were varied by using liquid media containing: (1) low carbon, low nitrogen, (2) low carbon, high nitrogen, (3) high carbon, low nitrogen, or (4) high carbon, high nitrogen . The protein arrays expressed under the four conditions were very similar, and endo-1,4-beta-glucanase (detected by 2-D gels) activity along with beta-glucosidase, xylanase, and NADH/quinone oxidoreductase activities were detected . Maximal expression of the hydrolytic enzymes was observed in high carbon/high nitrogen medium, whereas the highest oxidoreductase activity was in the high carbon low nitrogen medium . Oxalate and 2,5-dimethoxybenzoquinone were detected under all culture conditions, with higher production in high carbon/low nitrogen medium . Cultures grown in this medium also yielded the highest rate of hydroxylation of p-hydroxybenzoic acid, yielding protocatechuic acid, a product of hydroxyl radical attack.

ASAIO J, 2003 Jul-Aug, 49(4), 417 - 21
Biodegradation of polyglycolic acid-collagen composite tubes for nerve guide in the peritoneal cavity; Ito T et al.; The rate of biodegradation of new types of polyglycolic acid (PGA)-collagen composite tubes for nerve regeneration was evaluated in the peritoneal cavity . PGA mesh tubes with a diameter of 2 or 4 mm were coated with collagen solution and dried at room temperature . The tubes were then subjected to dehydrothermal treatment (composite tube) . A 2 mm PGA-collagen composite tube filled with collagen sponge was also investigated in this study (sponge tube) . Tubes with a length of 15 mm were fixed at the parietal peritoneum of BALB/c mice and excised 2 weeks and 1, 2, and 3 months after the operation . The inner areas of the excised tubes were measured microscopically . Statistical analysis was performed by one way ANOVA and Fisher's PLSD test . Although the inner areas of the 2 and 4 mm composite tubes were not maintained 1 month after the operation (62 +/- 6.8% and 21 +/- 3.8%, respectively), they were well maintained in the sponge tubes (83 +/- 6.4%) . The inner areas of the sponge tubes were significantly larger than those of the composite tubes until 2 months after surgery . These results suggest that sponge tubes are more suitable than composite tubes for nerve regeneration in the peritoneal cavity.

J Biomed Mater Res A, 2003 Sep 1, 66(3), 463 - 75
Effect of strain and strain rate on fatigue-accelerated biodegradation of polyurethane; Wiggins MJ et al.; A diaphragm-type film specimen was used to study in vitro degradation of poly(etherurethane urea) (PEUU) under conditions of dynamic loading . This geometry allowed both uniaxial and biaxial loading in a single experiment . During testing, the film was exposed to a H(2)O(2)/CoCl(2) solution that simulated in vivo oxidation of PEUU . The combination of dynamic loading and biaxial tensile strain accelerated oxidative degradation . The effects of biaxial strain magnitude and strain rate were examined separately by increasing the frequency of fatigue loading from 0 to 1 Hz with constant maximum biaxial strain and by changing the maximum biaxial strain while maintaining constant strain rate . In the ranges of biaxial strain energy (0.17 to 0.55 MPa) and strain rate (0 to 46% s(-1)) tested, the rate of degradation increased with increasing strain rate whereas strain magnitude had essentially no effect on degradation rate . Although loading conditions affected the rate of oxidative degradation, ATR-FTIR analysis suggested that in all cases the mechanism of degradation did not change . Chemical degradation produced a brittle crosslinked surface layer marked by dimpling and pitting, as observed with scanning electron microscopy . Pits served as stress concentrators and initiated environmental stress cracks under dynamic loading but not under static (creep) loading . Small pits were sufficient to initiate cracks at higher strain rates whereas only large pits initiated cracks at lower strain rates . Consequently, a higher strain rate produced more profuse cracking .

Water Res, 2003 Sep, 37(16), 3803 - 14
Kinetics of 4-nitrophenol biodegradation in a sequencing batch reactor; Tomei MC et al.; In this paper, the biodegradation process of 4-nitrophenol (4NP) in a sequencing batch reactor has been investigated . Kinetic tests have been carried out on biomass grown on mixed substrate (4NP plus biogenic substrate) both in the presence of a biogenic substrate fraction in the feed and with 4NP as the sole carbon source . Removal kinetics for all tests is well described by the typical substrate inhibition pattern as predicted by the Haldane equation . In both sets, estimated kinetic parameters are very similar: no beneficial effect of the biogenic fraction is observed on the 4NP removal while increasing trend of 4NP maximum removal rate with the 4NP/COD(TOT) ratio in the feed has been observed . This finding has been modelled by estimating the fraction of the total biomass involved in 4NP biodegradation as a function of 4NP concentration in the feed . High removal rates, short acclimation times and good settling characteristics of produced sludge (observed during the whole working period) confirm the suitability of periodic systems in enhancing the bacterial potentialities for biodegradation of xenobiotic compounds.

Mar Pollut Bull, 2003 Aug, 46(8), 983 - 90
Natural cleanup of heavy fuel oil on rocks: an in situ experiment; Jezequel R et al.; Changes in the chemical composition of a heavy fuel oil, Bunker C, exposed to the elements for 556 days in the vicinity of Brest Harbour (France, (48 degrees 18(') N, 4 degrees 32(') W)) have been studied . Samples with exposure to full or reflected sunlight, and in the dark, were analysed by thin layer chromatography and gas chromatography coupled with mass spectrometry and compared with the initial oil . Using hopane as a conserved internal standard, an average of more than 56% of the total hydrocarbon in the residual stranded oil had been removed in the 556 days . The results indicate that dissolution, biodegradation and photooxidation all play important roles in the weathering process, with their respective contributions depending on the exposure.

Environ Sci Technol, 2003 Jul 15, 37(14), 3095 - 103
Shifts in biodegradation kinetics of the herbicides MCPP and 2,4-D at low concentrations in aerobic aquifer materials; Torang L et al.; Biodegradation kinetics of two phenoxy acid herbicides, MCPP {(+/-)-2-(4-chloro-2-methylphenoxy)propanoic acid; mecoprop} and 2,4-D {2,4-dichlorophenoxyacetic acid} were studied in laboratory batch microcosms at low concentrations (0.025-100 microg/L) using 14C technique with sediments and groundwater from a shallow aerobic sandy aquifer . Below a certain threshold concentration of approximately 1 microg/L for 2,4-D and 10 microg/L for MCPP, the biodegradation followed first-order nongrowth kinetics, and no adaptation was observed within the experimental period of 341 d . Half-lifes for ultimate degradation were 500 d for 2,4-D and 1100 d for MCPP at 10 degrees C in unpolluted aquifer sediment in this environmentally relevant concentration regime . Above the threshold concentrations, the biodegradation rate accelerated gradually due to selective growth of specific biomass, which was ascertained from 14C most probable number enumerations of specific phenoxy acid degraders . Atthe highest concentration tested (100 microg/ L), specific degraders increased from 10(-1) to 10(5) cells/g during the experiment, and half-lifes after adaptation decreased to approximately 5 d . The enhanced rate of degradation by adapted systems was maintained during degradation of the last residuals measured to less than 0.1 microg/L . In situ long-term preexposure of the aquifer sediment also resulted in significant higher degradation rates of the phenoxy acids.

Mar Pollut Bull, 2003, 47(9-12), 397 - 405
Interaction of oil and mineral fines on shorelines: review and assessment; Owens EH et al.; The interaction of fine mineral particles with stranded oil in an aqueous medium reduces the adhesion of the oil to solid surfaces, such as sediments or bedrock . The net result is the formation of stable, micron-sized, oil droplets that disperse into the water column . In turn, the increase in surface area makes the oil more available for biodegradation . This interaction, referred to as oil-mineral aggregate (OMA) formation, can explain how oiled shorelines are cleaned naturally in the absence of wave action in very sheltered coastal environments . OMA formation also plays an important role in the efficacy of shoreline treatment techniques, such as physical mixing and sediment relocation that move oiled sediments into the zone of wave action to promote the interaction between oil and mineral fines . Successful application of these shoreline treatment options has been demonstrated at two spill events (the Tampa Bay response in Florida and the Sea Empress operation in Wales) and at a controlled oil spill experiment in the field (the 1997 Svalbard ITOSS program) . Sediment relocation harnesses the hydraulic action of waves so that the processes of fine-particle interaction and physical abrasion usually occur in tandem on open coasts . There has been no evidence of significant detrimental side-effects of residual oil in pelagic or benthic environments associated with the use of these treatment options to enhance rates of dispersion and oil biodegradation.

J Ind Microbiol Biotechnol, 2003 Sep, 30(9), 542 - 8 Epub 2003 Aug 01.
Microbial characterization and hydrocarbon biodegradation potential of natural bilge waste microflora; Olivera NL et al.; Shipping operations produce oily wastes that must be managed properly to avoid environmental pollution . The aim of this study was to characterize microorganisms occurring in ship bilge wastes placed in open lagoons and, particularly, to assess their potential to degrade polycyclic aromatic hydrocarbons (PAHs) . A first-order kinetic was suitable for describing hydrocarbon biodegradation after 17 days of treatment . The calculated rate constants were 0.0668 and 0.0513 day(-1) with a corresponding half-life of 10.3 and 13.5 days for the aliphatic and aromatic hydrocarbon fractions, respectively . At day 17, PAH removal percentages were: acenaphtylene 100, fluorene 95.2, phenanthrene 93.6, anthracene 70.3, and pyrene 71.5 . Methyl phenanthrene removals were lower than that of their parent compound (3-methyl phenanthrene 83.6, 2-methyl phenanthrene 80.8, 1-methyl phenanthrene 77.3, 9-methyl phenanthrene 75.1, and 2,7-dimethyl phenanthrene 76.6) . Neither pure cultures nor the microbial community from these wastes showed extracellular biosurfactant production suggesting that the addition of an exogenously produced biosurfactant may be important in enhancing hydrocarbon bioavailability and biodegradation . DNA analysis of bilge waste samples revealed a ubiquitous distribution of the nahAc genotype in the dump pools . Although almost all of the isolates grew on naphthalene as sole carbon source, only some of them yielded nahAc amplification under the experimental conditions used . The variety of PAHs in bilge wastes could support bacteria with multiple degradation pathways and a diversity of catabolic genes divergent from the classical nah-like type.

J Orthop Sci, 2003, 8(4), 549 - 53
Tissue response to porous hydroxyapatite ceramic in the human femoral head; Tachibana Y et al.; We describe pathohistological findings of the human femoral head after it was grafted with hydroxyapatite (HA) and allogenic bone . The femoral head was removed because of the recurrence of a giant cell tumor 15 months after the graft . Histological investigation revealed that the entire surface of the HA granules was completely surrounded by the bone in the periphery of the grafted area; in some areas granules were partly in contact with the existing bone, and the rest were surrounded by fibrous tissue . There was no intervening layer of fibrous tissue between the granule surface and the bone where they were in direct contact . Pores were completely filled with fibrous tissue, partially filled with bone in the periphery of the pores, or completely filled with bone . Undecalcified histology revealed the formation of osteoid and ossification at the site where fibrous tissue infiltrated the pores . These findings indicated continued ingrowth of new bone into the HA pores . Under a scanning electron microscope, the surfaces of the granules showed clear demarcation in vitro, but it became less smooth, indicating in vivo changes . Although no foreign body reaction to the HA was noted anywhere, the HA surface appeared to be subject to a biodegradation process.

Waste Manag, 2003, 23(5), 419 - 23
The effect of lignin and sugars to the aerobic decomposition of solid wastes; Komilis DP et al.; A series of experimental runs were conducted from 1995 to 1999 in Madison (WI, USA) with the goal to investigate the biodegradation process of seven (7) solid waste components and mixtures of them under near optimal aerobic conditions . It was shown that substrates with high initial lignin contents or high initial HWSM contents were observed to have relatively low and high degradation extents, respectively . Two linear equations were derived that correlate degradation extent (as indicated by the volatile solids reduction) to initial lignin and initial HWSM contents separately . The lignin equation was compared to a similar equation previously developed for anaerobic environments by Chandler et al . (Predicting methane fermentation biodegradability . In: Biotechnology and Bioengineering Symposium No . 10 (1980) New York: John Wiley & Sons) . With comparison to the Chandler formula, lignin was found to be less inhibitory to the overall substrate decomposition in aerobic environments compared to anaerobic ones . Cellulose loss contributed to a higher than 50% to the overall dry mass loss for all substrates studied . In addition, the cellulose to lignin (C/L) ratio appeared to be a relatively accurate compost maturity indicator, since it reduced to a value less than 0.5 for most substrates that had reached their degradation extent.

Carbohydr Res, 2003 Aug 12, 338(17), 1759 - 69
Biodegradation of poly(epsilon-caprolactone)/starch blends and composites in composting and culture environments: the effect of compatibilization on the inherent biodegradability of the host polymer; Singh RP et al.; The biodegradability of poly(epsilon-caprolactone) (PCL) was studied in blends and composites of modified and granular starch . Four types of PCL-starch compositions were prepared: (i) PCL-granular starch blends; (ii) hydrophobic coating of starch particles by n-butylisocyanate (C(4) starch) and octadecyltrichlorosilane (C(18) starch), followed by melt blending with PCL; (iii) PCL-starch blends compatibilized by PCL-g-dextran grafted copolymer (PGD); and (iv) PCL-grafted starch particles (PGS) as obtained by in situ ring-opening polymerization of caprolactone (CL) initiated directly from hydroxyl functions at the granular starch surface . Biodegradability of these materials was measured by monitoring the percentage of weight loss in composting and the rate of fungal colonization when samples were used as a sole carbon source for fungus (A . niger) . Intrinsic viscosity {eta} of host PCL chains was measured after extraction of composted samples in boiled chloroform . SEM was used to study the surface morphology after compost incubation of the samples . The inherent biodegradability of host polymer was enhanced with surface compatibilization during composting for longer incubation . It was observed that the weight loss during composting increased with the decrease in interfacial tension between filler and polymer . In general, it was concluded that inherent biodegradability does not depend very significantly on the concentration of starch in the polyester matrix, but on the compatibilization efficiency . The effect of the PCL fraction in the graft copolymer, when used as compatibilizer, was also studied on the biodegradability of the host polymer.

Chemosphere, 2003 Oct, 53(2), 101 - 9
Anaerobic biodegradation of weathered polychlorinated biphenyls (PCBs) in contaminated sediments of Porto Marghera (Venice Lagoon, Italy); Fava F et al.; The biodegradation of weathered polychlorinated biphenyls (PCBs) (mono and di-chlorinated biphenyls along with PCBs partially ascribed to Aroclor 1242 and 1254) occurring at 1.5-2.5 mg/kg in three different sediments collected from the Porto Marghera contaminated area of Venice Lagoon (Italy) was reported in this study . Strictly anaerobic, slurry microcosms consisting of sediments suspended (at 25% v/v) in a marine salt medium, lagoon water or lagoon water supplemented with NaHCO3 and Na2S were developed and monitored for PCB transformation, sulfate consumption and methane (CH4) production for 6 months . A marked depletion of highly chlorinated biphenyls along with the accumulation of low-chlorinated, often ortho-substituted biphenyls was observed in the biologically active microcosms, where a remarkable consumption of sulfate and/or a significant production of CH4 were also detected . Notably, a more extensive PCB transformation was observed in the microcosms developed with site water (both without or with NaHCO3 plus Na2S), where both the initial concentration of sulfate and sulfate consumption were five fold-higher than in the corresponding microcosms with salt medium . These data indicate that weathered PCBs of the three contaminated sediments of Porto Marghera utilized in this study can undergo reductive dechlorination, probably mediated by indigenous sulfate-reducing and/or methanogenic bacteria.

Drug Dev Ind Pharm, 2003 Jul, 29(6), 669 - 77
Biodegradation studies of rosin-based polymers; Satturwar PM et al.; This study was designed to investigate two rosin-based polymers (R-1 and R-2) for their in vitro and in vivo biodegradation behavior . The in vitro hydrolytic degradation was carried out in buffer solutions of pH 4.4, 7.4, and 10.4 at 37 degrees C . Enzymatic degradation was studied using enzymes lipase, pancreatine, and pectinase . Free films of the two polymers were subcutaneously implanted in rabbits for the in vivo biodegradation . The extent of degradation was determined quantitatively by weight loss and was followed qualitatively by scanning electron microscopy . The extent and the rate of degradation was better in vivo than in vitro . The polymers showed poor enzymatic degradation and a highly pH-dependent hydrolytic degradation.

J Biomed Mater Res A, 2003 Aug 1, 66(2), 417 - 24
Tailored delivery of active keratinocyte growth factor from biodegradable polymer formulations; Cho EJ et al.; We report the results of a high throughput screening campaign that is aimed to develop a biodegradable polymer-based formulation to deliver active keratinocyte growth factor (KGF) and provide a means to tune the KGF delivery rate . A statistical design strategy was used to prepare and screen a series of polymer blends that were composed of poly(lactic acid) (PLA), poly(glycolic acid) (PGA), and the surfactant sodium bis(ethylhexyl)sulfosuccinate (Aerosol-OT, AOT) . Chloroform was the solvent . Our high throughput screening method used a two-tiered assessment strategy . At Level 1, we identified "lead" KFG-loaded formulations that exhibited KGF emission spectra that were the most similar to the native KGF spectrum recorded in buffer . At Level 2, we used steady-state emission and a homogeneous polarization immunoassay strategy to determine the concentration of total and active KGF, respectively, liberated from the lead formulations during biodegradation . After preparing and screening 2500 formulations, we identified several viable, lead formulations . An analysis of the data showed that the combination of PLA, PGA, and AOT were important to yield a high fraction of active KGF upon release from the formulation; no combination of any two together produced an effect as good as the ternary formulation . The optimum formulations that yielded the highest fraction of active KGF upon release had the following general features: PLA/PGA (w/w) near unity, AOT loading of 100-200 mM, water/AOT mole ratio of 10-20, and a pH between 6 and 8 . PLA alone cast from chloroform delivered KGF, but that KGF did not bind to anti-KGF antibodies (i.e., it was inactive) . We can tune the KGF release kinetics by more than two orders of magnitude while maintaining the KGF activity upon liberation from the formulation by adjusting the PLA molecular weight .

Biotechnol Lett, 2003 May, 25(9), 731 - 8
Aerobic biodegradation of nonylphenol by cold-adapted bacteria; Soares A et al.; Three strains capable of mineralizing nonylphenol as sole carbon source were isolated from a sample of contaminated soil and characterized as two Pseudomonas spp . and a Stenotrophomonas sp . The two Pseudomonas spp . expressed characteristics typical of psychrophiles growing optimally of 10 degrees C and capable of growing at 0 degree C . The Stenotrophomonas sp . was more likely psychrotrophic because it had an optimal temperature between 14 and 22 degrees C although it was not capable of growing at 4 degrees C . At 14 degrees C, one of the Pseudomonas spp . exhibited the highest rate of degradation of nonylphenol (4.4 mg l-1 d-1), when compared with axenic or mixed cultures of the isolates . This study represents, to the best of our knowledge, the first reported case of cold-adapted microorganisms capable of mineralizing nonylphenol.

Biotechnol Lett, 2003 Apr, 25(7), 559 - 64
Toxicity and kinetic parameters of the aerobic biodegradation of the phenol and alkylphenols by a mixed culture; Acuna-Arguelles ME et al.; A mixed culture aerobically metabolized phenol, cresol isomers (o-,m-,p-), 2-ethylphenol and xylenol isomers (2,5-DMP and 3,4-DMP) as the sole carbon and energy source . This culture had a high tolerance towards phenol with values of maximum degradation rate (Vmax) of 47 microM phenol mg-1 protein h-1 and inhibition substrate constant (Ki) of 10 mM . These kinetic parameters were considerably diminished and the toxicity increased with the alkylphenols . For example with 2,5-xylenol, Vmax and Ki values of 0.8 microM 2,5-xylenol mg-1 protein h-1 and 1.3 mM, respectively, were obtained . The cresols were 5-fold more toxic than phenol, whereas 2-ethylphenol and 3,4-xylenol were 11-fold more toxic, and 2,5-xylenol was 34-fold more toxic than phenol.

Biodegradation, 2003 Apr, 14(2), 105 - 21
Slow complexation kinetics for ferric iron and EDTA complexes make EDTA non-biodegradable; Willett AI et al.; Published experimental data on ethylenediaminetetraacetic acid (EDTA) biodegradation in the presence of ferric iron (Fe(III)) showed that rapid biodegradation of EDTA suddenly stopped, leaving a residual of unbiodegraded EDTA that was equal to the concentration of dissolved Fe(III) . We hypothesize that slow kinetics for the dissociation of two iron-EDTA complexes--FeEDTA(-) and FeOHEDTA(2-)--sequestered the EDTA in a form that is biologically unavailable . To evaluate this hypothesis, we added to the biogeochemical model CCBATCH a new submodel for kinetically controlled complexation . CCBATCH simulations with kinetically controlled complexation for FeEDTA(-) and FeOHEDTA(2-) and the observed concentration of total dissolved Fe(III) accurately predicted the sudden cessation of EDTA biodegradation at the exact time shown experimentally . Our simulations also correctly predicted the observed residual EDTA concentration and the amounts of biomass and NH4+ . Alternate explanations for the experimental results--strong equilibrium complexation of ferric iron and EDTA and precipitation of calcium and magnesium solids--could not capture the observed trends . This analysis using CCBATCH's new sub-model for kinetically controlled complexation shows that EDTA, once it becomes complexed with Fe(III), becomes biologically unavailable.

Environ Sci Technol, 2003 Jul 1, 37(13), 2988 - 96
Biosurfactant- and biodegradation-enhanced partitioning of polycyclic aromatic hydrocarbons from nonaqueous-phase liquids; Garcia-Junco M et al.; A study was conducted on the effect of two different biological factors, microbial surfactants and biodegradation, on the kinetics of partitioning of polycyclic aromatic hydrocarbons (PAHs) from nonaqueous-phase liquids (NAPLs) . The effect of rhamnolipid biosurfactants on partitioning into the aqueous phase of naphthalene, fluorene, phenanthrene, and pyrene, initially dissolved in di-2-ethylhexyl phthalate (DEHP) or 2,2,4,4,6,8,8-heptamethylnonane (HMN), was determined in multiple-solute experiments . Biosurfactants at a concentration above the CMC enhanced the partitioning rate of fluorene, phenanthrene, and pyrene but were ineffective with naphthalene . Enhancement of partitioning was also observed in the presence of suspended humic acid-clay complexes, which simulated the solids often present in the subsurface . Biosurfactants sorbed to the complexes modified PAH partitioning between the NAPL and these solids, increasing the fraction of solid-phase PAH . Biodegradation-driven partitioning was estimated in mineralization experiments with phenanthrene initially present in HMN and three representative soil bacterial strains, differing in their potential adherence to the NAPL . In the three cases, the rates of mineralization were very similar and significantly higher than the abiotic rate of partitioning . Our study suggests that in NAPL-polluted sites, partitioning of PAH may be efficiently enhanced by in situ treatments involving the use of biosurfactants and biodegradation.

Environ Sci Technol, 2003 Jul 1, 37(13), 2913 - 9
Microbial respiration and diffusive transport of O2, 16O2, and 18O15O in unsaturated soils and geologic sediments; Lee ES et al.; Molecular oxygen (O2) in unsaturated geologic sediments plays an important role in soil respiration, biodegradation of organic contaminants, metal oxidation, and global oxygen and carbon cycling, yet little is known about oxygen isotope fractionation during the consumption and transport of O2 in unsaturated zones . We used a laboratory kinetic cell technique to quantify isotope fractionation due to respiration and a numerical model to quantify both consumptive and diffusive fractionation of O2 isotopes at a field site comprised of unsaturated lacustrine sandy materials . The combined use of laboratory-based kinetic cell experiments and field-based isotope transport modeling provided an effective tool to characterize microbial respiration in unsaturated media . Based on results from the closed-system kinetic cells, O2 consumption and isotope fractionation were attributed to the alternative cyanide-resistant respiration pathway . At the field site, the modeled depth profiles for O2 and delta18O matched the measured in situ data and confirmed that the consumption of O2 was via the alternative respiration pathway . If the cyanide-resistant respiration pathway is indeed widespread in soils, its high oxygen isotope enrichment factor could help to explain the discrepancy between the predicted present-day Dole effect (+20.8/1000) and the observed Dole effect (+23.5/1000) . Thus, further soil O2 isotope studies are needed to better characterize and model the fractionation of oxygen isotopes during subsurface respiration and the potential impact on the isotopic content of atmospheric O2.

Mutat Res, 2003 Jul 25, 528(1-2), 81 - 91
Environmental persistence of chemicals and their carcinogenic risks to humans; Pollack N et al.; A "chemical population"-based investigation of xenobiotics (i.e . a sample of 10,000 chemicals representative of agents in commerce, industry, and the environment, both synthetic and natural) that have the potential for ecotoxicity because of their persistence in the environment and their potential association with carcinogenic risks to humans was undertaken . The analyses revealed a statistically significant association between resistance to environmental biodegradation and the prevalence of chemical with the potential to induce systemic toxicity and cancer . On the other hand, there was no association between biopersistence and the potential for inducing toxicities unrelated to carcinogenesis, e.g . allergic contact dermatitis in humans and sensory irritation in mice.

Isotopes Environ Health Stud, 2003 Jun, 39(2), 113 - 24
In-situ biodegradation of tetrachloroethene and trichloroethene in contaminated aquifers monitored by stable isotope fractionation; Vieth A et al.; Stable carbon isotope analysis of tetrachloroethene (PCE) and trichloroethene (TCE) was applied to evaluatenatural attenuation processes in the upper Quaternary and lower Tertiary aquifer in the area of a former dry-cleaning plant located in Leipzig, Germany . Groundwater samples were taken during one monitoring campaign in 2001 . The 13C enrichment in contaminants along the water flow path suggested that both, PCE and TCE were degraded in the Quaternary aquifer . The enrichment of 13C in the residual PCE fraction and an isotope fractionation factor from laboratory experiments were used to calculate the extent of biodegradation in the Quatemary aquifer . These calculations indicated that a major portion of PCE was biodegraded in the course of the plume . In the Tertiary aquifer the carbon isotope ratios of PCE and TCE indicated that the decreasing concentrations of these contaminants were probably not caused by microbial processes.

Chemosphere, 2003 Sep, 52(10), 1743 - 8
Aerobic biodegradability of methyldiethanolamine (MDEA) used in natural gas sweetening plants in batch tests and continuous flow experiments; Furhacker M et al.; Mixtures of different amines including tertiary amines (methyldiethanolamine, MDEA) are commonly used for the removal of CO2 from gas mixtures or in gas sweetening processes for the extraction of CO2 and H2S . The absorber solutions used can be released into the industrial waste water due to continuous substitution of degraded MDEA, periodically cleaning processes or an accidental spill . In this study, the aerobic biodegradability of MDEA was investigated in a standardised batch test and a continuous flow experiment (40 l/d) . The results of the batch test indicated that the MDEA-solution was non-biodegradable during the test period of 28 days, whereas the continuous flow experiments showed biodegradation of more than 96% based on TOC-measurements . This was probably due to the adaptation of the microorganisms to this particular waste water contamination during continuous flow experiment.

Chemosphere, 2003 Sep, 52(10), 1717 - 26
Physicochemical soil parameters affecting sequestration and mycobacterial biodegradation of polycyclic aromatic hydrocarbons in soil; Bogan BW et al.; Six soils, obtained from grasslands and wooded areas in Northeastern Illinois, were physicochemically characterized . Measured parameters included total organic carbon (TOC) content, contents of humic acid, fulvic acid and humin, pore volume and pore size distribution, and chemical makeup of soil organic matter (determined using solid-state 13C-NMR) . Moistened, gamma-sterilized soils were spiked with 200 ppm of either phenanthrene or pyrene (including 14C label); following 0, 40, or 120 days of aging, the contaminant-spiked soils were then inoculated with Mycobacterium austroafricanum strain GTI-23, and evolution of 14CO2 was assessed over a 28-day period . Results for both phenanthrene and pyrene indicated that increased contact time led to increased sequestration and reduced biodegradation, and that TOC content was the most important parameter governing these processes . One soil, although only tested with phenanthrene, showed significantly lower-than-expected sequestration (higher-than-expected mineralization) after 40 days of aging, despite a very high TOC value (>24%) . Because the level of sequestration in this soil was proportional to the others after 120 days of aging, this implies some difference in the temporal progression of sequestration in this soil, although not in its final result . The primary distinguishing feature of this soil was its considerably elevated fulvic acid content . Further experiments showed that addition of exogenous fulvic acid to a soil with very low endogenous humic acids/fulvic acids content greatly enhanced pyrene mineralization by M . austroafricanum . Extractabilities of 13 three- to six-ring coal tar PAHs in n-butanol from the six soils after 120 days of sequestration were strongly TOC-dependent; however, there was no discernible correlation between n-butanol extractability and mycobacterial PAH mineralization.

Waste Manag Res, 2003 Jun, 21(3), 225 - 34
Assessing the effects of municipal solid waste incinerator bottom ash on the decomposition of biodegradable waste using a completely mixed anaerobic reactor; Banks CJ et al.; Experimental lab scale anaerobic reactors were used to assess the effect of municipal solid waste incinerator (MSWI) bottom ash on the process of biodegradation of organic materials typical of those found in municipal solid waste (MSW) . Three reactors were used in the trial and each of these received the same daily organic load of simulated MSW but varying loads of MSWI bottom ash . The reactors were monitored over a period of 200 days for pH, alkalinity, volatile acids, total organic carbon (TOC), biogas production, gas composition and heavy metals . The addition of ash appeared to have beneficial effects on the degradation process as there was an increase in gas production, alkalinity, and pH, coupled with a decrease in the TOC concentration of leachate when compared with a control reactor without MSWI ash addition . After 200 days operation, the alkalinity and gas production in the anaerobic reactor receiving 6g ash per day was twice that of the reactor receiving 3g of ash per day and four times that of the control reactor . A number of tests were carried out on the ash sample to investigate the possible reasons for enhancement of the biodegradative process . These included a shake flask batch leaching test using distilled water, determination of the acid neutralising capacity by titration curve, and the quantification of six heavy metals and four light metals . In the reactors receiving ash the concentrations of Ca, Na, K, Mg ions were found to be significantly higher and these may provide a higher alkalinity which could promote the digestion process . Soluble concentrations of Cd, Cr, Cu, Ni, Pb, and Zn were in the range of 0.02-0.2, 0.01-2.5, 0.01-0.3, 0.01-1, 0.01-1.2, and 0.01-1 mgl(-1) respectively and at these concentrations it is unlikely that they would prove inhibitory to the digestion process.

Environ Technol, 2003 Jun, 24(6), 679 - 86
Analysis of secondary metabolite fate during anaerobic-aerobic azo dye biodegradation in a sequential batch reactor; Lourenco ND et al.; A great number of the reported examples of azo dye biodegradation comprise two main steps, the reductive cleavage of the azo bond under anaerobic conditions and the subsequent aerobic mineralization of the produced aromatic amines . Based on this possible metabolism a Sequencing Batch Reactor was chosen to study biologicalcolor removal from simulated cotton textile effluents containing a reactive azo dye . In previous studies high color removal levels of the azo dye Remazol Brilliant Violet 5R were achieved (up to 90% with an initial dye concentration of 100 mg l(-1)) during the anaerobic phase of Sequencing Batch Reactor operation . However, HPLC analyses revealed that the aromatic amines formed in the anaerobic phase were not mineralized during the subsequent aerobic phase . In an attempt to promote the aerobic biodegradation of these aromatic amines three different approaches were tested, the increase of the relative duration of the aerobic phase, the increase of the hydraulic retention time through the decrease of the daily fill flow and finally the increase of the dye/carbon source concentration ratio through the decrease of the fed volumetric organic load . The two aromatic amines directly resulting from azo bond reduction were detected by HPLC analysis . However, a third metabolite with significant peak area was also detected with a time profile suggesting an equilibrium with one of the aromatic amines In spite of the conversions occurring between metabolites during the cycles of the tested approaches, no effective biodegradation of these metabolites was observed during the experimental period of over 810 days.

Chemosphere, 2003 Sep, 52(9), 1531 - 7
Removal of biocide pentachlorophenol in water system by the spent mushroom compost of Pleurotus pulmonarius; Law WM et al.; Pentachlorophenol (PCP) has been widely used as a wood preservative since 1980s . Although it has been banned worldwide, residues of PCP are still commonly found . The spent compost of oyster mushroom Pleurotus pulmonarius (SMC) which was a degraded paddy straw-based substrate, contained 25% chitin . Five percentage of the SMC could remove 89.0 +/- 0.4% of 100 mg PCPl(-1) within 2 days at room temperature predominantly by biodegradation . The maximum removal capacity was 15.5 +/- 1.0 mg g(-1) SMC . The sorption kinetics of PCP by SMC can be described by the Freundlich monolayer model with a theoretical sorption capacity similar to that found for chitin . A PCP-degradative bacterium was isolated from the SMC . Yet, biodegradation was predominantly contributed by the immobilized ligninolytic enzymes secreted by the mushroom to the SMC . Degradation of PCP involves dechlorination, methylation, carboxylation and ring cleavage as verified by GC-MSD and ion chromatography . Thus, the SMC has a potential for treating PCP-contaminated water.

Chemosphere, 2003 Sep, 52(9), 1515 - 21
Biodegradability of Atrazine, Cyanazine and Dicamba under methanogenic condition in three soils of China; Gu JG et al.; Persistence and degradation of the herbicides Atrazine, Cyanazine and Dicamba were measured in laboratory microcosms incubated under methanogenic condition using three soils of China . Results showed that Atrazine was more resistant to degradation than Cyanazine and Dicamba for the 300 days of incubation . Between 30% and 40% of the initially introduced chemicals were found to be not recoverable through solvent extraction of the incubated soils . Our results also indicated that the half-life of these herbicides in the three soils generally followed: Atrazine>Cyanazine>Dicamba . Biodegradation of Cyanazine and Dicamba was further substantiated by establishing enrichment cultures in which the degradation of the respective herbicides could be accelerated by the microorganisms . Our results suggest that biodegradation of xenobiotics can be established through enrichment culture transfer technique and non-extractability of chemicals should be taken into account in evaluation of chemicals' fate and risk.

Chemosphere, 2003 Sep, 52(9), 1423 - 30
Fate and assessment of persistent organic pollutants in water and sediment from Minjiang River Estuary, Southeast China; Zhang ZL et al.; Persistent organochlorine compounds were analyzed in surface water, porewater and surficial sediment samples from Minjiang River Estuary, which is the first large river in Fujian Province, Southeast of China . The total concentrations of 18 organochlorine pesticides were 214.4-1819, 4541-13,699 ng/l, 28.79-52.07 ng/g in surface water, porewater and sediments (dry weight) respectively, and those of 21 polychlorinated biphenyls (PCBs) in the three phases were: 203.9-2473, 3192-10,855 ng/l, 15.14-57.93 ng/g respectively . The results showed that the concentrations of these selected organochlorine pesticides and PCBs in porewater were higher than those in surface water . It may be due to the fact that these organic hydrophobic pollutants tend to stay in the sediments, and then re-suspend from the sedimentary phase to the upper water . We have analyzed the distribution characteristics of individual organochlorine pesticide components and PCBs, and found that alpha-HCH, DDE, Heptachlor, Endosulfan II, Methoxychlor were the most common organochlorine pesticides contaminants . Considering the groups of HCHs (HCHs=alpha-HCH+beta-HCH+gamma-HCH+delta-HCH) and DDTs (DDTs=DDT+DDD+DDE), the predominance of beta-HCH, DDE in all water, porewater and sediment samples was clearly observed . This observation suggested that beta-HCH was resistant to biodegradation and the DDTs had been transformed to its metabolites, DDE and DDD, of which DDE that was more un-degradable . The PCB congeners containing 3-6 chlorines had the great preponderance in the three phase . These results were compared with those present in other estuaries and harbors . A risk assessment was evaluated for the persistent organic pollutants in the Minjiang River Estuary.

Water Sci Technol, 2003, 47(10), 41 - 7
Treatment of phenolic wastewater using agricultural wastes as an adsorbent in a sequencing batch reactor; Lee KM et al.; The objective of this study is to investigate the potential of the activated rice husk to be used as an alternative adsorbent to powdered activated carbon (PAC) in the simultaneous adsorption and biodegradation processes under sequencing batch reactor (SBR) operation to treat synthetic wastewater containing phenol, p-methylphenol, p-ethylphenol and p-isopropylphenol . The rice husk (PRH) was activated by pyrolysis at 600 degrees C for 5 hours in a nitrogen atmosphere . Using the Langmuir model, the limiting adsorption capacities of PRH for the phenols were found to vary from 0.015-0.05 of those of PAC . The SBR reactors with and without adsorbent addition were operated with fill, react, settle, draw and idle periods in the ratio of 4:6:1:0.76:0.25 for a cycle time of 12 hours . For phenolic wastewater containing, 1,200 mg/L phenol, 1,200 mg/L p-methylphenol, 800 mg/L p-ethylphenol and 660 mg/L p-isopropylphenol, it was found that the biodegradation process alone was unable to produce effluent of quality which would satisfy the discharge standards of COD < or = 100 mg/L and phenol concentration < or = 1 mg/L . The addition of PAC in the ratio of PAC/phenolic compound at 0.095 g/g for phenol, 0.119 g/g for p-methylpheol, 0.179 g/g for p-ethylphenol and 0.220 g/g for p-isopropylphenol, can improve the effluent quality to satisfy the discharge standards . Equivalent treatment performance was achieved with the use of PRH at dosages of 2-3 times higher than those of PAC for all the phenolic wastewater studied . The increased adsorption capacity of PRH shown in the treatment indicates bioregeneration of the adsorbed surface during the treatment process.

J Biomed Mater Res B Appl Biomater, 2003 Aug 15, 66(2), 539 - 47
Long-term study of high-strength hydroxyapatite/poly(L-lactide) composite rods for the internal fixation of bone fractures: a 2-4-year follow-up study in rabbits; Ishii S et al.; Biodegradation of hydroxyapatite (HA)/poly(L-lactide)(PLLA) composite bone implant rods was studied with the use of two types of HA particles as reinforcing fillers: uncalcined HA (u-HA) or calcined HA (c-HA) . Composite rods of u-HA/PLLA and c-HA/PLLA containing 30 or 40% (w/w) HA were implanted in the distal femur of 21 rabbits, and specimens were examined by light microscopy, scanning-electron microscopy (SEM), and transmission-electron microscopy (TEM) 2-4 years later . For u-HA/PLLA, trabecular bone bonding directly onto the rod was maintained for up to 2 years . By 3 years, surface collapse had begun, and the implants were shrinking . By 4 years, they had shrunk further, with complete bone encapsulation . The u-HA particles were small and needle shaped in the peripheries, and TEM confirmed their resorption . The cross-sectional area after 4 years decreased by 23.3+/-8.4% . The mean ratio of bony ingrowth to the initial cross-sectional area around the shrunken rods was 6.7+/-1.3 % . The viscosity molecular weight of PLLA reduced from 2 x 10(5) to less than 1 x 10(3) . Thus, most of the PLLA had released from the rods . The c-HA/PLLA implants also showed good osteoconductivity, but shrinkage and infiltration of histiocytes were less . No osteolytic or osteoarthritic changes were found .

Biomacromolecules, 2003 Jul-Aug, 4(4), 1087 - 91
Synthesis and characterization of sugar-bearing chitosan derivatives: aqueous solubility and biodegradability; Park JH et al.; The extended use of chitosan in biomedical fields has been limited by its insoluble nature in a biological solution . To endow the water solubility in a broad range of pH, chitosan derivatives were prepared by the covalent attachment of a hydrophilic sugar moiety, gluconic acid, through the formation of an amide bond . These sugar-bearing chitosans (SBCs) were further modified by the N-acetylation in an alcoholic aqueous solution . Thereafter, the effect of the gluconyl group and the degree of N-acetylation (DA) on the water solubility at different pHs and on the biodegradability of chitosan were investigated . The SBCs showed the water solubility in a broader range of pH than chitosan, whereas they were still insoluble at neutral and alkali pH . The N-acetylation of SBCs significantly affected the water solubility, for example, the SBCs with the DA, ranging from 29% to 63%, were soluble in the whole range of pH . This might result from the improved hydrophilicity by the gluconyl group, accompanied by the role of the N-acetyl group that disturbed the hydrogen bonding between amino groups of chitosan . From the biodegradation tests, determined by the decrease in the viscosity of a polymer solution exposed to lysozyme, it was evident that the gluconyl group attached to chitosan improved the biodegradability . Thus, it was possible to control the biodegradability of chitosan by adjusting the amounts of gluconyl and N-acetyl groups in the chitosan backbone . The N-acetylated SBCs, soluble in the broad range of pH, might be useful for various biomedical applications.

J Contam Hydrol, 2003 Aug, 65(1-2), 101 - 20
Microbial in situ degradation of aromatic hydrocarbons in a contaminated aquifer monitored by carbon isotope fractionation; Richnow HH et al.; We present an approach for characterizing in situ microbial degradation using the 13C/12C isotope fractionation of contaminants as an indicator of biodegradation . The 13C/12C isotope fractionation of aromatic hydrocarbons was studied in anoxic laboratory soil percolation columns with toluene or o-xylene as the sole carbon and electron source, and sulfate as electron acceptor . After approximately 2 months' of incubation, the soil microbial community degraded 32 mg toluene l(-1) and 44 mg o-xylene l(-1) to less than 0.05 mg l(-1), generating a stable concentration gradient in the column . The 13C/12C isotope ratio in the residual non-degraded fraction of toluene and o-xylene increased significantly, corresponding to isotope fractionation factors (alphaC) of 1.0015 and 1.0011, respectively . When the extent of biodegradation in the soil column was calculated based on the measured isotope ratios (R(t)) and an isotope fractionation factor (alphaC=1.0017) obtained from a sulfate-reducing batch culture the theoretical residual substrate concentrations (C(t)) matched the measured toluene concentrations in the column . This indicated that a calculation of biodegradation based on isotope fractionation could work in systems like soil columns . In a field study, a polluted, anoxic aquifer was analyzed for BTEX and PAH contaminants . These compounds were found to exhibit a significant concentration gradient along an 800-m groundwater flow path downstream of the source of contamination . A distinct increase in the carbon isotope ratio (delta13C) was observed for the residual non-degraded toluene (7.2 per thousand ), o-xylene (8.1 per thousand ) and naphthalene fractions (1.2 per thousand ) . Based on the isotope values and the laboratory-derived isotope fractionation factors for toluene and o-xylene, the extent to which the residual substrate fraction in the monitoring wells had been degraded by microorganisms was calculated . The results revealed significant biodegradation along the groundwater flow path . In the wells at the end of the plume, the bioavailable toluene and o-xylene fractions had been almost completely reduced by in situ microbial degradation . Although indane and indene showed decreasing concentrations downstream of the groundwater flow path, suggesting microbial degradation, their carbon isotope ratios remained constant . As the physical properties of these compounds are similar to those of BTEX compounds, the constant isotope values of indane and indene indicated that microbial degradation did not lead to isotope fractionation of all aromatic hydrocarbons . In addition, physical interaction with the aquifer material during the groundwater passage did not significantly alter the carbon isotope composition of aromatic hydrocarbons.

Med Device Technol, 2003 Jun, 14(5), 12 - 5
Biological safety testing of polymers; Baldrick P; The extent of testing polymer-containing medical devices is subject to a range of considerations and needs to be determined on a case-by-case basis . This article reports on recent areas of concern for device materials including biodegradation and immunogenicity potential.

Curr Opin Biotechnol, 2003 Jun, 14(3), 262 - 9
The role of mobile genetic elements in bacterial adaptation to xenobiotic organic compounds; Top EM et al.; Retrospective studies clearly indicate that mobile genetic elements (MGEs) play a major role in the in situ spread and even de novo construction of catabolic pathways in bacteria, allowing bacterial communities to rapidly adapt to new xenobiotics . The construction of novel pathways seems to occur by an assembly process that involves horizontal gene transfer: different appropriate genes or gene modules that encode different parts of the novel pathway are recruited from phylogenetically related or distant hosts into one single host . Direct evidence for the importance of catabolic MGEs in bacterial adaptation to xenobiotics stems from observed correlations between catabolic gene transfer and accelerated biodegradation in several habitats and from studies that monitor catabolic MGEs in polluted sites.

J Microbiol Methods, 2003 Sep, 54(3), 419 - 22
Bacterial degradation of dichloromethane in cultures and natural environments; Krausova VI et al.; Dichloromethane (DCM) is a toxic pollutant showing prolonged persistence in water . DCM biodegradation is usually determined from increases in Cl ions, gas chromatography, or by using radioisotopes . Herein, we present an original and easy spectrophotometric method to estimate DCM concentrations in cultures and environmental samples during DCM biodegradation experiments.

Res Microbiol, 2003 Jun, 154(5), 321 - 8
The microbiology of hydrocarbon degradation in subsurface petroleum reservoirs: perspectives and prospects; Roling WF et al.; The majority of the Earth's petroleum resource is partly biodegraded . This is of considerable practical significance and can limit economic exploitation of petroleum reserves and lead to problems during petroleum production . Knowledge of the microorganisms present in petroleum reservoirs, their physiological properties and the biochemical potential for hydrocarbon degradation benefits successful petroleum exploration . Anaerobic conditions prevail in petroleum reservoirs and biological hydrocarbon degradation is apparently inhibited at temperatures above 80-90 degrees C . We summarise available knowledge and conjecture on the dominant biological processes active during subsurface petroleum biodegradation.

Environ Toxicol Chem, 2003 Jul, 22(7), 1428 - 36
The bioaccumulation and fate of a branched 14C-p-nonylphenol isomer in Lymnaea stagnalis L; Lalah JO et al.; A single branched isomer of p-nonylphenol, 4(3',6'-dimethyl-3'-heptyl)-phenol, previously identified by gas chromatography-mass spectrometry as one of the major constituent isomers in p-nonylphenol (constituting approximately 10% of all its isomers), was synthesized and used in studies of its bioaccumulation and excretion in the hermophroditic pond snail Lymnaea stagnalis L . Branched isomers of nonylphenol are perceived to have more estrogenlike toxicity than the straight-chain isomers in addition to being more resistant to biodegradation in the environment . With an average static exposure concentration of 104 microg/L (range: 92-116 microg/L) in water at 19 degrees C for 8 d, the uptake of the compound was found to be fairly rapid, reaching a peak concentration of 23,548 microg/kg of whole tissue wet weight after 5 d and a peak bioaccumulation factor (BAFw) of 242 (5,562, based on lipid weight) after 3 d . The uptake data fitted into a logarithmic expression C(t) = 5,231 ln(t) + 11,956, where C(t) is the amount of residues accumulated in whole tissue in micrograms per kilogram tissue wet weight after a period of time, t, and t is the period of exposure in days . By determination of the excretion of 14C-residues released in water and in feces, an average loss of 96% of the accumulated residues was achieved after 22 d of continuous exposure to clean water . By first-order kinetics analysis of the excretion data, an average half-life of excretion of 4.9 d was obtained . By high-performance liquid chromatography and gas-liquid chromatography-mass spectrometry, a catechol metabolite, 4(3',6'-dimethyl-3'-heptyl)-catechol, was detected in tissue extracts (after hydrolysis with beta-glucuronidase) and in feces, in addition to the parent isomer, suggesting that the isomer may have been metabolized by glucuronic acid conjugation and hydroxylation at the ortho position of its phenolic ring.

Environ Toxicol Chem, 2003 Jul, 22(7), 1421 - 7
Variations in alpha-hexachlorocyclohexane enantiomer ratios in relation to microbial activity in a temperate estuary; Padma TV et al.; Changes in the enantiomer ratios (ERs) of chiral pollutants in the environment are often considered evidence of biological alteration despite the lack of data on causal or mechanistic relationships between microbial parameters and ER values . Enantiomer ratios that deviate from 1:1 in the environment provide evidence for the preferential microbial degradation of one enantiomer, whereas ER values equal to 1 provide no evidence for microbial degradation and may mistakenly be interpreted as evidence that biodegradation is not important . In an attempt to link biological and geochemical information related to enantioselective processes, we measured the ERs of the chiral pesticide alpha-hexachlorocyclohexane (alpha-HCH) and bacterial activity (normalized to abundance) in surface waters of the York River (VA, USA) bimonthly throughout one year . Despite lower overall alpha-HCH concentrations, alpha-HCH ER values were unexpectedly close to 1:1 in the freshwater region of the estuary with the highest bacterial activity . In contrast, ER values were nonracemic (ER double dagger 1) and alpha-HCH concentrations were significantly higher in the higher salinity region of the estuary, where bacterial activity was lower . Examination of these data may indicate that racemic environmental ER values are not necessarily reflective of a lack of biodegradation or recent input into the environment, and that nonenantioselective biodegradation may be important in certain areas.

J Hazard Mater, 2003 Jun 27, 100(1-3), 245 - 57
Bioslurry treatment for soils contaminated with very high concentrations of 2,4,6-trinitrophenylmethylnitramine (tetryl); Fuller ME et al.; Past and current DoD activities have resulted in the contamination of soil, sediment and groundwater with various explosive compounds . This research was undertaken to determine the effectiveness of a soil bioslurry process for remediation of soil with very high concentrations of 2,4,6-trinitrophenylmethylnitramine (tetryl) . A 99.9% reduction in tetryl concentrations (from 100,000 to below 100 mg/kg) was achieved in 180 to 200 days . A variety of process modifications (i.e . addition of fertilizer, microbial biomass, purging with nitrogen, etc.) that were performed during the course of the experiment did not increase the tetryl biodegradation rate beyond the rates of degradation without modifications . Subsequent batches of soil added as a 25% (v/v) replacement of the slurry were also degraded . These results indicate the potential for this process to remediate highly contaminated soils at many former and current ammunition manufacturing sites.

J Hazard Mater, 2003 Jun 27, 100(1-3), 39 - 52
Numerical simulation of gas flow around a passive vent in a sanitary landfill; Chen YC et al.; A numerical model, based on the Darcy law, was used to simulate the two-dimensional gas flow around a passive vent in a sanitary landfill . We follow Findikakis and Leckie {ASCE J . Environ . Eng . 105 (1979) 927} in modeling the biodegradation of the solid waste and assume the first-order biodegradation kinetics . The numerical results from the Fresh Kills landfill, New York, show that the well's ability in extracting the landfill gas by the passive vent decays quickly with the increase of the radial distance from the well . The influence radius of the well is generally less than 20 m . The effects from the final soil thickness, well depth, and other parameters on the gas flow are also discussed.

Water Res, 2003 Aug, 37(14), 3499 - 507
Stimulating the anaerobic biodegradation of explosives by the addition of hydrogen or electron donors that produce hydrogen; Adrian NR et al.; The anaerobic biodegradation of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX), and 2,4,6-trinitrotoluene (TNT) by a methanogenic mixed culture was investigated . Microcosms containing a basal medium and the mixed culture were amended with ethanol, propylene glycol (PG), butyrate or hydrogen gas as the electron donor and a mixture of TNT (50 microM), RDX (25 microM), and HMX (8 microM) . After 29 days TNT and RDX were completely transformed to unidentified endproducts in the bottles amended with ethanol, hydrogen, or PG, while 53%, 40%, and 22% of the HMX was transformed, respectively . There was no loss of RDX or HMX in the electron donor unamended control bottles . The ethanol and PG were transformed to near stoichiometric amounts of acetate and propionate, suggesting the immediate electron donor supporting the transformation of the explosives was the H2 evolved during the metabolism of the parent substrate . Our findings suggest that the addition of H2 or electron donors that produce H2 may be a useful strategy for enhancing the anaerobic biodegradation of explosives in contaminated groundwater and soils.

Water Res, 2003 Aug, 37(14), 3401 - 11
Fate of organics during soil-aquifer treatment: sustainability of removals in the field; Quanrud DM et al.; A 5-year program of study was conducted at the Sweetwater Recharge Facilities (SRF) to assess the performance of surface spreading operations for organics attenuation during field-scale soil-aquifer treatment (SAT) of municipal wastewater . Studies were conducted utilizing both mature (approximately 10 yr old) and new infiltration basins . Removals of dissolved organic carbon (DOC) were robust, averaging >90 percent during percolation through the local 37-m vadose zone . The hydrophilic (most polar) fraction of DOC was preferentially removed during SAT; removals were attributed primarily to biodegradation . Reductions in trihalomethane formation potential (THMFP) averaged 91 percent across the vadose zone profile . The reactivity (specific THMFP) of post-SAT organic residuals with chlorine decreased slightly from pre-SAT levels (60 vs . 72 microg THM per mg DOC, respectively) . Variations in the duration of wetting/drying periods did not significantly impact organic removal efficiencies.

Water Res, 2003 Aug, 37(14), 3299 - 306
Laboratory studies of dissolved radiolabelled microcystin-LR in lake water; Hyenstrand P et al.; The fate of dissolved microcystin-LR was studied in laboratory experiments using surface water taken from a eutrophic lake . Based on initial range finding, a concentration of 50 microg l(-1) dissolved 14C-microcystin-LR was selected for subsequent time-course experiments . The first was performed in May before the cyanobacterial bloom season and low increases in the radioactivity of particulate fractions occurred with an approx . halving of the cyano-toxin during 4 days . The radioactivity of the dissolved fraction remained stable and there was no significant formation of radiolabelled inorganic carbon . A second time-course experiment was performed in September during the cyanobacterial bloom season . At the end of the four-day incubation period, the microcystin-LR concentration had decreased to an undetectable level and 24% of the added radiolabelled substance was found in different particulate fractions . The study demonstrated that biodegradation of dissolved microcystin-LR occurred in water collected at a lake surface with carbon dioxide as a major end-product.

Proteomics, 2003 Jun, 3(6), 1066 - 9
Proteomic changes in Escherichia coli TG1 after metabolic engineering for enhanced trichloroethene biodegradation; Pferdeort VA et al.; Through metabolic engineering, new enzymatic pathways can be introduced into cells to enable or enhance production or biotransformation of chemicals . However, these changes have physiological consequences that can be important but are not well understood . Here we describe the use of two-dimensional gel electrophoresis (2-DE) to detect changes in the proteome of Escherichia coli cells that have been engineered to transform the pollutant trichloroethene (TCE) with the enzyme toluene o-monooxygenase (TOM) . Comparison of 2-DE gels (isoelectric point range 4-7) for E . coli cells with and without the ability to synthesize TOM revealed 31 new proteins in TOM-containing cells as well as nine proteins not detected in those cells but present in the plasmid control strain . Exposure of TOM-containing cells to TCE led to the synthesis of four new proteins and the loss of only one protein . Thus, this example of metabolic engineering has a substantial and complex impact on the physiology of these cells that was clearly revealed using a proteomic approach.

Water Sci Technol, 2003, 47(9), 157 - 64
Kinetics of biodegradation during remediation of consecutive accidental spills of chlorophenols in a sandy aquifer; Antizar-Ladislao B et al.; Kinetics of biodegradation of chlorophenols were studied in six sandy aquifer columns (0.06 m I.D.; 1.00 m L) . Remediation of chlorophenols was enhanced by using a "closed-loop" configuration system, where local groundwater was recirculated through the polluted site in a controlled manner . Consecutive accidental spills of phenol, 2-monochlorophenol (2-MCP) and 2,4,6-trichlorophenol (2,4,6-TCP) as single pollutants were removed following first order kinetics . The removal of chlorophenols increased by one order of magnitude following consecutive accidental spills demonstrating adaptation of the resident micro flora . The biodegradation rate constants in this study were in the same range and agreed with those reported in the literature for biodegradation in aerobic aquifers . Following the fate of the resident micro flora (enhanced by adding NH4Cl and KH2PO4 at a ratio C/N/P equal to 120:10:1), biomass growth was observed in the sandy aquifer columns and particle size analyses of the aqueous phase recirculated through the polluted site experimentally proved aggregation of cells . Aggregation of cells has been hypothesized as one of the causes for low biodegradation rates found in the field compared to those calculated using biodegradation rate constants determined in batch culture.

Environ Health Perspect, 2003 Jun, 111(8), 1093 - 101
Impact of metals on the biodegradation of organic pollutants; Sandrin TR et al.; Forty percent of hazardous waste sites in the United States are co-contaminated with organic and metal pollutants . Data from both aerobic and anaerobic systems demonstrate that biodegradation of the organic component can be reduced by metal toxicity . Metal bioavailability, determined primarily by medium composition/soil type and pH, governs the extent to which metals affect biodegradation . Failure to consider bioavailability rather than total metal likely accounts for much of the enormous variability among reports of inhibitory concentrations of metals . Metals appear to affect organic biodegradation through impacting both the physiology and ecology of organic degrading microorganisms . Recent approaches to increasing organic biodegradation in the presence of metals involve reduction of metal bioavailability and include the use of metal-resistant bacteria, treatment additives, and clay minerals . The addition of divalent cations and adjustment of pH are additional strategies currently under investigation.

Ultrason Sonochem, 2003 Jul, 10(4-5), 241 - 6
A combination of ultrasound and oxidative enzyme: sono-biodegradation of substituted phenols; Entezari MH et al.; Sonolysis, enzyme treatment, and a combination of the two processes were tested for the degradation of substituted phenols (phenol, p-chlorophenol, p-bromophenol, p-iodophenol, p-methoxyphenol, p-cresol and p-nitrophenol) in aqueous medium . These organic pollutants are divided into three groups according to their degradation behaviour . In group (I), p-nitrophenol, horseradish peroxidase (HRP) in presence of hydrogen peroxide had a negligible effect on its decomposition . The combined method showed the same effect as sonolysis . Therefore, it is convenient to degrade p-nitrophenol by ultrasonic waves alone . In group (II), p-methoxyphenol and p-cresol, the combined method was approximately the same as enzyme treatment . It means that, the ultrasound had a negligible effect and the enzyme treatment alone was more favourable . Phenol and its halogenated compounds (choloro, bromo and iodo) were placed in group (III) and showed different behaviour than the two mentioned cases . The combined method was more efficient than the sonolysis and enzyme treatment individually . It should be noted that the effect of enzyme on this group (III) was in the medium level in compare of the two other groups (I and II) which the enzyme had a lower and higher effects respectively.

J Contam Hydrol, 2003 Jul, 64(3-4), 269 - 81
Carbon and hydrogen isotope effects during sorption of organic contaminants on carbonaceous materials; Schuth C et al.; Stable carbon and hydrogen isotopes can be an efficient means to validate biodegradation of organic contaminants in groundwater since it results in an isotopic fractionation . A prerequisite in applying this method in the field is the proof that other processes decreasing the contaminant concentration are conservative with respect to isotope effects . In this paper we show for carbon isotopes of halogenated hydrocarbon compounds {trichloroethene (TCE), cis-dichloroethene (c-DCE), vinylchloride (VC)} and carbon and hydrogen isotopes of BTEX compounds (benzene, toluene, p-xylene) that no significant fractionation occurs during equilibrium sorption onto activated carbon, lignite coke and lignite . In general, effects were in the range of the reproducibility limit of the analytical instrument (0.5 per thousand for delta13C, and 8 per thousand for delta2H) . This observation was made for fractions sorbed of less than 5% to more than 95% . Also for rate-limited sorption of TCE onto activated carbon, no significant fractionation in carbon isotopes could be observed . These findings support the assumption that for these classes of compounds, sorption processes in aquifer systems are conservative with respect to isotope effects.

J Contam Hydrol, 2003 Jul, 64(3-4), 253 - 67
Changes in enantiomeric fraction as evidence of natural attenuation of mecoprop in a limestone aquifer; Williams GM et al.; Natural attenuation of the chiral pesticide mecoprop {2-(2-methyl-4-chlorophenoxy)propionic acid} has been studied by determining changes in its enantiomeric fraction in different redox environments down gradient of a landfill in the Lincolnshire Limestone . Previous studies have shown that mecoprop degrades predominantly aerobically and that differences in the biological behaviour of the two enantiomers will change their relative proportions during biodegradation . Originally deposited as a racemic mixture, there has been no change in the enantiomeric fraction in the most polluted part of the landfill plume where conditions are sulphate reducing/methanogenic . In the nitrate-reducing zone, the proportion of (S)-mecoprop increases, suggesting preferential degradation of (R)-mecoprop; while in the aerobic zone, the proportion of (R)-mecoprop increases, suggesting faster degradation of (S)-mecoprop . Mecoprop persistence in the confined Lincolnshire Limestone further downdip is explained by inhibition of degradation in sulphate-reducing conditions, which develop naturally . Laboratory microcosm experiments using up to 10 mg l(-1) of mecoprop confirm these inferences and show that under aerobic conditions, (S)-mecoprop and (R)-mecoprop degrade with zero-order kinetics at rates of 1.90 and 1.32 mg l(-1) day(-1), respectively . Under nitrate-reducing conditions (S)-mecoprop does not degrade, but (R)-mecoprop degrades with zero-order kinetics at 0.65 mg l(-1) day(-1) to produce a stoichiometric equivalent amount of 4-chloro-2-methylphenol . This metabolite only degrades when the (R)-mecoprop has disappeared . The addition of nitrate to a dormant iron-reducing microcosm devoid of nitrate stimulated anaerobic degradation of (R)-mecoprop after a lag period of 21 days . There was no evidence for enantiomeric inversion . The study demonstrates the sensitivity of changes in enantiomeric fraction for detecting natural attenuation, and reveals subtle differences in mecoprop degradation in different redox environments within the Lincolnshire Limestone aquifer.

J Contam Hydrol, 2003 Jul, 64(3-4), 191 - 202
Use of tracer tests to evaluate the impact of enhanced-solubilization flushing on in-situ biodegradation; Alter SR et al.; Tracer tests were conducted to evaluate the effect of a complexing sugar flush (CSF) on in-situ biodegradation potential at a site contaminated by jet fuel, solvents, and other organic compounds . Technical-grade hydroxypropyl-beta-cyclodextrin was used during the CSF study, which was conducted in a hydraulically isolated cell emplaced in a surficial aquifer . In-situ biodegradation potential was assessed with the use of tracer tests, which were conducted prior to and immediately following the CSF study . Ethanol, hexanol, and benzoate were used as the biodegradable tracers, while bromide was used as a nonreactive tracer . The results indicate that the biodegradation of benzoate was similar for both tracer tests . Conversely, the biodegradation of ethanol (23% increase) and hexanol (41% increase) was greater for the post-CSF tracer test . In addition, analysis of core samples collected from within the test cell indicates that the population density of aerobic jet-fuel degraders increased in the vicinity of the injection wells during the CSF . These results indicate that the cyclodextrin flush did not deleteriously affect the indigenous microbial community . This study illustrates that tracer tests can be used to evaluate the impact of remediation activities on in-situ biodegradation potential.

J Contam Hydrol, 2003 Jul, 64(3-4), 151 - 68
Natural attenuation of trichloroethylene in fractured shale bedrock; Lenczewski M et al.; This paper describes one of the first well-documented field examples of natural attenuation of trichloroethylene (TCE) in groundwater in a fractured shale bedrock . The study was carried out adjacent to a former waste burial site in Waste Area Grouping 5 (WAG5) on the Oak Ridge Reservation, Oak Ridge, TN . A contaminant plume containing TCE and its daughter products were detected downgradient from the buried waste pits, with most of the contamination occurring in the upper 6 m of the bedrock . The monitoring well array consists of a 35-m-long transect of multilevel sampling wells, situated along a line between the waste pits and a seep which discharges into a small stream . Concentrations of volatile organic carbons (VOCs) were highest in the waste trenches and decreased with distance downgradient towards the seep . Sampling wells indicated the presence of overlapping plumes of TCE, cis-dichloroethylene (cDCE), vinyl chloride (VC), ethylene, ethane, and methane, with the daughter products extending further downgradient than the parent (TCE) . This type of distribution suggests anaerobic biodegradation . Measurements of redox potential at the site indicated that iron-reduction, sulfate reduction, and potentially methanogensis were occurring and are conducive to dechlorination of TCE . Bacteria enrichment of groundwater samples revealed the presence of methanotrophs, methanogens, iron-reducing bacteria and sulfate-reducing bacteria, all of which have previously been implicated in anaerobic biodegradation of TCE . 16S rDNA sequence from DNA extracted from two wells were similar to sequences of organisms previously implicated in the anaerobic biodegradation of chlorinated solvents . The combined data strongly suggest that anaerobic biodegradation of the highly chlorinated compounds is occurring . Aerobic biodegradation may also be occurring in oxygenated zones, including near a seep where groundwater exits the site, or in the upper bedrock during seasonal fluctuations in water table elevation and oxygen levels.

Biomaterials, 2003 Sep, 24(20), 3437 - 44
Photocrosslinkable chitosan hydrogel containing fibroblast growth factor-2 stimulates wound healing in healing-impaired db/db mice; Obara K et al.; Application of ultraviolet light (UV-) irradiation to a photocrosslinkable chitosan (Az-CH-LA) aqueous solution including fibroblast growth factor-2 (FGF-2) resulted within 30s in an insoluble, flexible hydrogel . About 20% of the FGF-2molecules were released from the FGF-2-incorporated chitosan hydrogel into phosphate buffered saline (PBS) within 1 day, after which no further significant release occurred under in vitro non-degradation conditions of the hydrogel . The FGF-2molecules retained in the chitosan hydrogel remained biologically active, and were released from the chitosan hydrogel upon the in vivo biodegradation of the hydrogel . In order to evaluate its accelerating effect on wound healing, full thickness skin incisions were made on the back of healing-impaired diabetic (db/db) mice and their normal (db/+) littermates . Application of the chitosan hydrogel significantly induced wound contraction and accelerated wound closure in both db/db and db/+ mice . However, the addition of FGF-2 in the chitosan hydrogel further accelerated wound closure in db/db mice, although not in db/+ mice . Histological examination also has demonstrated an advanced granulation tissue formation, capillary formation and epithelialization in wounds treated with FGF-2-incorporated chitosan hydrogels in db/db mice.

ScientificWorldJournal, 2002 May 16, 2, 1338 - 46
Kinetics of natural attenuation of BTEX: review of the critical chemical conditions and measurements at bore scale; Atteia O et al.; This paper describes the chemical conditions that should favour the biodegradation of organic pollutants . Thermodynamic considerations help to define the reaction that can occur under defined chemical conditions . The BTEX (benzene, toluene, ethylbenzene, and xylene) degradation is focused on benzene, as it is the most toxic oil component and also because it has the slowest degradation rate under most field conditions . Several studies on benzene degradation allow the understanding of the basic degradation mechanisms and their importance in field conditions . The use of models is needed to interpret field data when transport, retardation, and degradation occur . A detailed comparison of two existing models shows that the limits imposed by oxygen transport must be simulated precisely to reach correct plumes shapes and dimensions, and that first-order kinetic approaches may be misleading . This analysis led us to develop a technique to measure directly biodegradation in the field . The technique to recirculate water at the borehole scale and the CO2 analysis are depicted . First results of biodegradation show that this technique is able to easily detect the degradation of 1 mg/l of hydrocarbons and that, in oxic media, a fast degradation rate of mixed fuel is observed.

ScientificWorldJournal, 2002 May 11, 2, 1281 - 95
Fructan biosynthetic and breakdown enzymes in dicots evolved from different invertases . Expression of fructan genes throughout chicory development; Van den Ende W et al.; Fructans are fructose-based oligo- and polymers that serve as reserve carbohydrates in many plant species . The biochemistry of fructan biosynthesis in dicots has been resolved, and the respective cDNAs have been cloned . Recent progress has now succeeded in elucidating the biochemistry and molecular biology of fructan biodegradation in chicory, an economically important species used for commercial inulin extraction . Unlike fructan biosynthetic genes that originated from vacuolar-type invertase, fructan exohydrolases (FEHs) seem to have evolved from a cell-wall invertase ancestor gene that later obtained a low iso-electric point and a vacuolar targeting signal . Expression analysis reveals that fructan enzymes are controlled mainly at the transcriptional level . Using chicory as a model system, northern analysis was consistent with enzymatic activity measurements and observed carbohydrate changes throughout its development.

ScientificWorldJournal, 2002 May 08, 2, 1227 - 34
Isotope fractionation of toluene: a perspective to characterise microbial in situ degradation; Richnow HH et al.; A concept to assess in situ biodegradation of organic contaminants in aquifers is presented . The alteration of the carbon isotope composition of contaminants along the groundwater flow path indicates microbial degradation processes and can be used as an indicator for in situ biodegradation . The Rayleigh equation was applied to calculate the percentage of the in situ biodegradation (B{%}) using the change in the isotopic composition of contaminants (Rt/R0) along the ground water flow path and a kinetic carbon isotope fractionation factor (alphaC) derived from defined biodegradation experiments in the laboratory . When the groundwater hydrology is known and a representative source concentration (C0) for a groundwater flow path can be determined, the extent of in situ biodegradation can be quantified.

Biochem Biophys Res Commun, 2003 Jun 27, 306(2), 509 - 15
Mechanism of xanthine oxidase catalyzed biotransformation of HMX under anaerobic conditions; Bhushan B et al.; Enzyme catalyzed biotransformation of the energetic chemical octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) is not known . The present study describes a xanthine oxidase (XO) catalyzed biotransformation of HMX to provide insight into the biodegradation pathway of this energetic chemical . The rates of biotransformation under aerobic and anaerobic conditions were 1.6+/-0.2 and 10.5+/-0.9 nmolh(-1)mgprotein(-1), respectively, indicating that anaerobic conditions favored the reaction . The biotransformation rate was about 6-fold higher using NADH as an electron-donor compared to xanthine . During the course of reaction, the products obtained were nitrite (NO(2)(-)), methylenedinitramine (MDNA), 4-nitro-2,4-diazabutanal (NDAB), formaldehyde (HCHO), nitrous oxide (N(2)O), formic acid (HCOOH), and ammonium (NH(4)(+)) . The product distribution gave carbon and nitrogen mass-balances of 91% and 88%, respectively . A comparative study with native-, deflavo-, and desulfo-XO and the site-specific inhibition studies showed that HMX biotransformation occurred at the FAD-site of XO . Nitrite stoichiometry revealed that an initial single N-denitration step was sufficient for the spontaneous decomposition of HMX.

Biodegradation, 2003, 14(1), 51 - 6
Stoichiometry of the aerobic biodegradation of the organic fraction of municipal solid waste (MSW); Liwarska-Bizukojc E et al.; An elemental analysis was applied to describe the composition of the organic fraction of municipal solid waste (MSW) . The initial elemental composition was constant at C5H8.5O4N0.2 . The changes of the composition during the biodegradation process and the final waste composition were strictly dependent on the process conditions . The decrease in carbon content due to biodegradation increased with temperature at which the experiments were conducted, from 20% at 20 degrees C to about 40% at 37-42 degrees C after 96 hours . It was correlated with the amount of oxygen that was utilised in the investigated processes of aerobic biodegradation of the waste suspension . The amount of oxygen required for biodegradation of organic fraction of MSW was estimated on the basis of stoichiometric equations and increased from 0.92 moles per 1 mole of waste at 20 degrees C to 1.6 moles at 42 degrees C within 96 hours of the experiments.

Biodegradation, 2003, 14(1), 1 - 8
Application of microscopic fungi isolated from polluted industrial areas for polycyclic aromatic hydrocarbons and pentachlorophenol reduction; Szewczyk R et al.; The growth abilities of fifteen fungal strains isolated from contaminated areas, in the presence of xenobiotics compounds mixture (overworked cutting fluid, crude and waste oil) were examined . Strains with the richest growth were chosen for anthracene, phenanthrene and pentachlorophenol biodegradation in Sabouraud medium (with initial xenobiotic concentration 250 mg/l in cultures with polycyclic aromatic hydrocarbons and 10 mg/l for the chlorinated substrate) . Strains IM 1063 and IM 6325 were able to attack phenanthrene forming its derivative 9-phenanthrenol with the yields 5.22 mg/l and 2.82 mg/l, respectively . Strain IM 1063 and IM 6325 transformed pentachlorophenol to an intermediate compound--pentachloromethoxybenzene . Final content of pentachloromethoxybenzene reached 3.46 mg/l and 3.2 mg/l, respectively . Strain IM 6203 (contrary to other strains) released an intermediate product of pentachlorophenol metabolism--2,3,5,6-tetrachlorohydroquinone (8.73 mg/l substrate remaining and 1.2 mg/l 2,3,5,6-tetrachlorohydroquinone forming) . The IM 6203 strain was identified as Mucor ramosissimus . The chlorinated pesticide degradation by M . ramosissimus was improved significantly on a medium with overworked oil . Only 8.3% of pentachlorophenol and 4.3% of 2,3,5,6-tetrachlorohydroquinone in relation to the introduced substrate (10 mg/l) were found, after 7 days of incubation . The growth of M . ramosissimus on medium with overworked oil in pentachlorophenol presence was associated with oil emulgation, which enhanced fungal growth and the pesticide degradation.

Appl Biochem Biotechnol, 2003 Apr-Jun, 109(1-3), 139 - 53
Codigestion of proteinaceous industrial waste; Braun R et al.; Organic wastes are increasingly collected source separated, thus requiring additional treatment or recovery capacities for municipal biowastes, organic industrial wastes, as well as agroindustrial byproducts . In this study, we demonstrate that anaerobic digestion is preferentially suited for highwater- containing liquid or pasty waste materials . We also evaluate the suitability of various organic wastes and byproducts as substrates for anaerobic digestion and provide a current status survey of codigestion . Biodegradation tests and estimations of the biogas yield were carried out with semisolid and pasty proteins and lipids containing byproducts from slaughterhouses; pharmaceutical, food, and beverage industries; distilleries; and municipal biowastes . Biogas yields in batch tests ranged from 0.3 to 1.36 L/g of volatile solidsadded . In continuous fermentation tests, hydraulic retention times (HRTs) between 12 and 60 d, at a fermentation temperature of 35 degrees C, were required for stable operation and maximum gas yield . Laboratory experiments were scaled up to full-scale codigestion trials in municipal and agricultural digestion plants . Up to 30% cosubstrate addition was investigated, using municipal sewage sludge as well as cattle manure as basic substrate . Depending on addition rate and cosubstrate composition, the digester biogas productivity could be increased by 80-400% . About 5-15% cosubstrate addition proved to be best suited, without causing any detrimental effects on the digestion process or on the further use of the digestate.

Water Sci Technol, 2003, 47(7-8), 243 - 50
Effect of non-aqueous phase liquid on biodegradation of PAHs in spilled oil on tidal flat; Kose T et al.; Biodegradation rates of polycyclic aromatic hydrocarbons (PAHs) in spilled oil stranded on tidal flats were studied using model reactors to clarify the effects of NAPL on the biodegradation of PAHs in stranded oil on tidal flat with special emphasis on the relationship between dissolution rates of PAHs into water and viscosity of NAPL . Biodegradation of PAHs in NAPL was limited by the dissolution rates of PAHs into water . Biodegradation rate of chrysene was smaller than that for acenaphthene and phenanthrene due to the smaller dissolution rates . Dissolution rates of PAHs in fuel oil C were smaller those in crude oil due to high viscosity of fuel oil C . Therefore, biodegradation rates of PAHs in fuel oil C were smaller than those in crude oil . Biodegradation rates of PAHs in NAPL with slow decrease rate like fuel oil C were slower than those in NAPL with rapid decrease like crude oil . The smaller decrease rate of fuel oil C than crude oil was due to higher viscosity of fuel oil C . Therefore, not only the dissolution rate of PAHs but also the decrease rates of NAPL were important factors for the biodegradation of PAHs.

J Bone Joint Surg Br, 2003 May, 85(4), 504 - 9
Zirconia and alumina ceramics in comparison with stainless-steel heads . Polyethylene wear after a minimum ten-year follow-up; Hernigou P et al.; Although alumina has been used in orthopaedic surgery since the 1970s, the long-term clinical results of zirconia have not been well documented in vivo . We studied hips with these two different ceramics during the same period and with a minimum follow-up of ten years . Because the size of the alumina and zirconia heads was different, hips with 32 mm alumina heads and those with 28 mm zirconia heads were compared with control hips with stainless-steel heads of the same size . Our aim was to compare the two ceramics . There was an increased linear rate of penetration of the femoral heads into the liner between years five and 12 for the zirconia and the stainless-steel groups . This was severe in the zirconia group (0.4 mm/year compared with 0.13 mm/year for the stainless-steel group) . During the same 12-year period there was, however, no significant change in the rate of wear in the alumina group (0.07 mm/year) . The mean wear at the most recent follow-up was 1360 mm3 for the 28 mm zirconia group, 683 mm3 for the 28 mm stainless-steel group, 755 mm3 for the 32 mm alumina group and 1314 mm3 for the 32 mm stainless-steel group . The monoclinic content rose on the surface of three zirconia heads which were retrieved at revision . This change was associated with an increase in the surface roughness . A change in the roundness with an increase in the sphericity deviation was also observed both in the articular and non-articular parts of the femoral heads . The increase in rate of wear in the zirconia group was only evident after eight years and may be linked to a long-term biodegradation of zirconia in vivo, associated with the altered roughness and roundness which was observed on the retrieved heads.

Appl Environ Microbiol, 2003 Jun, 69(6), 3350 - 8
Detection and enumeration of aromatic oxygenase genes by multiplex and real-time PCR; Baldwin BR et al.; Our abilities to detect and enumerate pollutant-biodegrading microorganisms in the environment are rapidly advancing with the development of molecular genetic techniques . Techniques based on multiplex and real-time PCR amplification of aromatic oxygenase genes were developed to detect and quantify aromatic catabolic pathways, respectively . PCR primer sets were identified for the large subunits of aromatic oxygenases from alignments of known gene sequences and tested with genetically well-characterized strains . In all, primer sets which allowed amplification of naphthalene dioxygenase, biphenyl dioxygenase, toluene dioxygenase, xylene monooxygenase, phenol monooxygenase, and ring-hydroxylating toluene monooxygenase genes were identified . For each primer set, the length of the observed amplification product matched the length predicted from published sequences, and specificity was confirmed by hybridization . Primer sets were grouped according to the annealing temperature for multiplex PCR permitting simultaneous detection of various genotypes responsible for aromatic hydrocarbon biodegradation . Real-time PCR using SYBR green I was employed with the individual primer sets to determine the gene copy number . Optimum polymerization temperatures for real-time PCR were determined on the basis of the observed melting temperatures of the desired products . When a polymerization temperature of 4 to 5 degrees C below the melting temperature was used, background fluorescence signals were greatly reduced, allowing detection limits of 2 x 10(2) copies per reaction mixture . Improved in situ microbial characterization will provide more accurate assessment of pollutant biodegradation, enhance studies of the ecology of contaminated sites, and facilitate assessment of the impact of remediation technologies on indigenous microbial populations.

Mar Pollut Bull, 2003, 47(1-6), 105 - 13
Study on the fate of petroleum-derived polycyclic aromatic hydrocarbons (PAHs) and the effect of chemical dispersant using an enclosed ecosystem, mesocosm; Yamada M et al.; Polycyclic Aromatic Hydrocarbons (PAHs) are one of the components found in oil and are of interest because some are toxic . We studied the environmental fate of PAHs and the effects of chemical dispersants using experimental 500 l mesocosm tanks that mimic natural ecosystems . The tanks were filled with seawater spiked with the water-soluble fraction of heavy residual oil . Water samples and settling particles in the tanks were collected periodically and 38 PAH compounds were analyzed by gas chromatography-mass spectrometry (GC-MS) . Low molecular weight (LMW) PAHs with less than three benzene rings disappeared rapidly, mostly within 2 days . On the other hand, high molecular weight (HMW) PAHs with more than four benzene rings remained in the water column for a longer time, up to 9 days . Also, significant portions (10-94%) of HMW PAHs settled to the bottom and were caught in the sediment trap . The addition of chemical dispersant accelerated dissolution and biodegradation of PAHs, especially HMW PAHs . The dispersant amplified the amounts of PAHs found in the water column . The amplification was the greater for the more hydrophobic PAHs, with an enrichment factor of up to six times . The increased PAHs resulting from dispersant use overwhelmed the normal degradation and, as a result, higher concentrations of PAHs were observed in water column throughout the experimental period . We conclude that the addition of the dispersant could increase the concentration of water column PAHs and thus increase the exposure and potential toxicity for organisms in the natural environment . By making more hydrocarbon material available to the water column, the application of dispersant reduced the settling of PAHs . For the tank with dispersant, only 6% of chrysene initially introduced was detected in the sediment trap whereas 70% was found in the trap in the tank without dispersant.

Environ Sci Technol, 2003 May 15, 37(10), 2127 - 33
Small-volume releases of gasoline in the vadose zone: impact of the additives MTBE and ethanol on groundwater quality; Dakhel N et al.; A controlled gasoline spill experiment was performed under outdoor conditions typical for winter in temperate regions to study the fate of methyl tert-butyl ether (MTBE), ethanol, benzene, and selected other petroleum hydrocarbons . Artificial gasoline containing MTBE and ethanol (5% w/w of each) was placed at a defined depth into a 2.3 m thick unsaturated zone of alluvial sand overlying a gravel aquifer in a lysimeter . During an initial period of 41 days without recharge, MTBE and hydrocarbon vapors migrated by vapor-phase diffusion to groundwater, while ethanol vapors were naturally attenuated . In a subsequent period of 30 days with 5-mm daily recharge, all soluble compounds including ethanol were transported to the groundwater . Ethanol disappeared concomitantly with benzene and all other petroleum hydrocarbons except isooctane from the aerobic groundwater due to biodegradation . MTBE persisted for longer than 6 months at concentrations larger than 125000 microg L(-1) . No evidence for MTBE biodegradation was found, whereas > 99.6% of ethanol removal from the lysimeter was due to biodegradation . It is concluded that MTBE-free gasoline would be less harmful for groundwater resources and that ethanol is an acceptable substitute.

Chemosphere, 2003 Aug, 52(6), 967 - 73
Comparative studies of fungal degradation of single or mixed bioaccessible reactive azo dyes; Martins MA et al.; A screening using several fungi (Phanerochaete chrysosporium, Pleurotus ostreatus, Trametes versicolor and Aureobasidium pullulans) was performed on the degradation of syringol derivatives of azo dyes possessing either carboxylic or sulphonic groups, under optimized conditions previously established by us . T . versicolor showed the best biodegradation performance and its potential was confirmed by the degradation of differently substituted fungal bioaccessible dyes . Enzymatic assays (lignin peroxidase, manganese peroxidase, laccase, proteases and glyoxal oxidase) and GC-MS analysis were performed upon the assay obtained using the most degraded dye . The identification of hydroxylated metabolites allowed us to propose a possible metabolic pathway . Biodegradation assays using mixtures of these bioaccessible dyes were performed to evaluate the possibility of a fungal wastewater treatment for textile industries.

Chemosphere, 2003 Aug, 52(6), 951 - 8
CO(2)-H(2)-dependent anaerobic biotransformation of phthalic acid isomers in sediment slurries; Liu SM et al.; This paper investigates the anaerobic biotransformation of three isomers of phthalic acid and benzoic acid in sediment slurries under four different atmospheres {N(2), N(2)/H(2) (19:1, v/v), CO(2), and CO(2)/H(2) (4:1, v/v)} . Significant differences were observed in lag periods and biotransformation rates among the phthalic acid isomers and under the different atmospheres . In most cases, the relative biotransformation rates of the three isomers of phthalic acid were ortho-phthalic acid>isophthalic acid>terephthalic acid . Benzoate was transformed faster than any isomer of phthalic acid . Since biotransformation of phthalic acid isomers in sediment slurries was enhanced by high initial levels of H(2) and CO(2) in the headspace, we propose a pathway for phthalic acid biodegradation in which the initial transformation to benzoate is CO(2)-H(2) dependent . Acetogenic bacteria were investigated for their possible involvement in this transformation reaction, but when MPN counts were used to compare the growth dynamics of acetogenic bacteria with the time course of the terephthalic acid transformation under N(2)/H(2) (19:1, v/v) and CO(2)/H(2) (4:1, v/v) atmospheres, the results were inconclusive.

Environ Sci Technol, 2003 May 1, 37(9), 1905 - 11
Dissolved oxygen imaging in a porous medium to investigate biodegradation in a plume with limited electron acceptor supply; Huang WE et al.; A novel combination of noninvasive imaging with an oxygen sensitive fluorescent indicator was developed to investigate the biodegradation processes occurring at the fringe of a solute plume, where the supply of oxygen was limited . A thin transparent porous matrix (156 x 120 x 3 mm) was made from quartz plates and quartz sand (212-300 microm) and enriched with acetate-degrading bacteria . A degrading plume developed from a continuous acetate source in the uniform flow field containing dissolved oxygen . Ruthenium (II)-dichlorotris(1,10-phenanthroline) (Ru(phen)3Cl2), a water-soluble fluorescent dye, was used as an indicator of dissolved oxygen . The fluorescence intensity was dependent on the concentration of oxygen because the dissolved oxygen acted as collisional quencher . The oxygen distribution was interpreted from images recorded by a CCD camera . These two-dimensional experimental results showed quantitatively how the oxygen concentrations decreased strongly at the narrow plume fringe and that oxygen was depleted at the core of the plume . Separately, dispersivity was measured in a series of nonreactive transport experiments, and biodegradation parameters were evaluated by batch experiments . Two-dimensional numerical simulations with MT3D/RT3D used these parameters, and the predicted oxygen distributions were compared with the experimental results . This measurement method provides a novel approach to investigate details of solute transport and biodegradation in porous media.

J Environ Sci Health A Tox Hazard Subst Environ Eng, 2003 Jun, 38(6), 1087 - 97
Anaerobic biodegradation of toluene coupled to sulfate reduction in oil-contaminated soils: optimum environmental conditions for field applications; Noh SL et al.; Degradation characteristics of toluene in enrichment culture were investigated in soil microcosms study and the optimum environmental conditions for anaerobic degradation of toluene coupled with sulfate reduction were determined for field site applications . Anaerobic sulfate-reducing bacteria were enriched from oil contaminated soil samples with toluene . Enriched consortia degraded toluene with sulfate as a terminal electron acceptor . The average degradation rate of toluene in enriched consortia ranged from 0.08 to 0.1 micromol g(-1) day(-1) . Toluene degradation under sulfate-reducing condition was inhibited in the presence of molybdate alone or together with nitrate or fumarate, indicating that toluene is degraded directly by sulfate-reducing bacteria . Effects of initial toluene concentration, pH, temperature, and other hydrocarbons on toluene degradation were investigated . There is a trend of increasing rate of toluene degradation with increasing the initial mass up to 94 micromol of toluene . Toluene degradation did not affected by the presence of ethylbenzene and xylene, as a while, toluene was degraded in a slower rate in the presence of benzene . The sulfate-reducing bacteria in the enriched culture showed higher microbial activity at neutral (pH 6-8) and medium temperature (30-37 degrees C) environments.

J Chem Inf Comput Sci, 2003 May-Jun, 43(3), 1051 - 7
Microbial pathway prediction: a functional group approach; Hou BK et al.; We have developed a system to predict microbial catabolism, using the University of Minnesota Biocatalysis/Biodegradation Database (UM-BBD, as a knowledge base . The present system, available on the Web , can predict biodegradation of most of the major aliphatic and aromatic organic functional groups containing C, H, N, O, and halogens . It can duplicate at least one known biodegradation pathway for 60% of the compounds in a 84-member validation set; most pathways that did not completely duplicate known metabolism could plausibly occur in nature . Users are encouraged, and have begun, to submit additional biotransformation rules and comment on existing rules; the system will further develop under the direction of the scientific community.

J Biomed Mater Res A, 2003 Jun 15, 65(4), 524 - 35
Biodegradation of polyurethane under fatigue loading; Wiggins MJ et al.; A method utilizing expansion of a diaphragm-type film specimen was developed to study in vitro biodegradation of poly(etherurethane urea) (PEUU) under conditions of dynamic loading (fatigue) . A finite element model was used to describe the strain state, which ranged from uniaxial at the edges of the film to balanced biaxial tensile strain at the center . During testing, the film was exposed to a H(2)O(2)/CoCl(2) solution, which simulated in vivo oxidative biodegradation of PEUU . The extent of chemical degradation was determined by infrared analysis . Physical damage of the film surface was characterized by optical microscopy and scanning electron microscopy . Dynamic loading did not affect the rate of degradation relative to unstressed and constant stress (creep) controls in regions of the film that experienced primarily uniaxial fatigue; however, degradation was accelerated in regions that experienced balanced biaxial or almost balanced biaxial fatigue . It was concluded that the combination of dynamic loading and biaxial tensile strain accelerated oxidative degradation in this system . Chemical degradation produced a brittle surface layer that was marked by numerous pits and dimples . Physical damage of the surface in the form of cracking occurred only in fatigue experiments . Cracking was not observed in unstressed or creep tests . Cracks initiated at the dimples produced by chemical degradation, and propagated in a direction that was determined by the strain state .

Chemosphere, 2003 Aug, 52(5), 861 - 8
Biodegradation of potential diesel oxygenate additives: dibutyl maleate (DBM), and tripropylene glycol methyl ether (TGME); Marchetti AA et al.; The addition of oxygen-bearing compounds to diesel fuel considerably reduces particulate emissions . TGME and DBM have been identified as possible diesel additives based on their physicochemical characteristics and performance in engine tests . Although these compounds will reduce particulate emissions, their potential environmental impacts are unknown . As a means of characterizing their persistence in environmental media such as soil and groundwater, we conducted a series of biodegradation tests of DBM and TGME . Benzene and methyl tertiary butyl ether (MTBE) were also tested as reference compounds . Primary degradation of DBM fully occurred within 3 days, while TGME presented a lag phase of approximately 8 days and was not completely degraded by day 28 . Benzene primary degradation occurred completely by day 3 and MTBE did not degrade at all . The total mineralized fractions of DBM and TGME achieved constant values as a function of time of approximately 65% and approximately 40%, respectively . Transport predictions show that, released to the environment, DBM and TGME would concentrate mostly in soils and waters with minimal impact to air . From an environmental standpoint, these results combined with the transport predictions indicate that DBM is a better choice than TGME as a diesel additive.

Prikl Biokhim Mikrobiol, 2003 May-Jun, 39(3), 318 - 21
{Use of bacteria of the genus Azotobacter for biodegradation of oil-contaminated soils}; Gradova NB et al.; The rate of self-purification of oil-contaminated soil increases after introduction of bacteria of the genus Azotobacter . The bacteria can assimilate oil hydrocarbons as the sole source of carbon and energy, both in the presence of fixed nitrogen and during nitrogen fixation . The species Azotobacter chroococcum activates growth of hydrocarbon-oxidizing bacteria present in Devoroil.

Pigment Cell Res, 2003 Jun, 16(3), 280 - 6
Melanosome degradation: fact or fiction; Borovansky J et al.; Our mini review summarizes what is known about the (bio)degradation of melanosomes . Unlike melanosome biogenesis where our knowledge enables us to explain it in molecular terms posing many interesting questions on the relation between lysosomes and melanosomes, melanosome degradation has remained 'terra incognita' . Observations at optical and ultrastructural levels describe the disintegration of melanosomes in the lysosomal compartment (in auto- and heterophagosomes) . Histochemical studies suggest the participation of acid hydrolases in the process of melanosome degradation . Biochemical data confirm the ability of lysosomal hydrolases to degrade melanosome constituents except the melanin moiety . The similarity of melanin structure to that of polycyclic aromatic hydrocarbons suggests that melanin should be sensitive mainly, if not exclusively, to oxidative breakdown . In vitro melanin can indeed be decomposed by an oxidative attack and the degradation is accompanied by fluorescence and decreasing absorbance . From enzymes engaged in the biotransformation of polycyclic hydrocarbons only phagosomal NADPH oxidase meets the criteria (particularly as for compartmental and catalytic properties) to be involved in melanin biodegradation . The in vivo biodegradation of melanin has so far been clearly demonstrated in Aspergillus and fungi melanins.

Dent Traumatol, 2003 Jun, 19(3), 139 - 44
The early tissue response to titanium and LactoSorb screws; Mollaoglu N et al.; Fractures of the maxillofacial region are common in the elderly people . Titanium and LactoSorb screws are the widely accepted materials for use in the maxillofacial fractures . This study was undertaken to evaluate the early tissue response following the insertion of both titanium and LactoSorb screws composed of 82% PLLA and 18% PGA in an elderly animal model . In this study, 22 titanium and 22 LactoSorb screws were applied to calvaria of 44 guinea pigs that were 10-11 months old . Animals were sacrificed on postoperative days 3, 7, 14, 30 and 60 . Screws were retrieved with surrounding bone tissue and the specimens were prepared for routine histologic examination . All the specimens were evaluated by light microscopy . Histometric analysis revealed that there was no significant difference between LactoSorb and titanium screws for the new bone formation . The biodegradation of LactoSorb screws was not complete by the end of day 60 . In conclusion, both materials were well tolerated and induced bone formation without causing adverse tissue response in an elderly animal model . Our results suggest that both LactoSorb and titanium miniplates and screws can be used safely, regardless of the increasing age . However, LactoSorb may be the first choice as it does not require a second operation for removal and has late biodegradation in elderly that keeps its support for a relatively longer time during fracture healing.

Artif Organs, 2003 May, 27(5), 437 - 43
Biomimetic mineralization of charged collagen matrices: in vitro and in vivo study; Goissis G et al.; Polyanionic collagen matrix prepared by hydrolysis side chain amides of asparagine and glutamine was mineralized in vivo, without inflammatory response, biodegradation, or resorption, with calcium phosphate deposited in close resemblance to the D-periodicity of collagen fibrils assembly . In vitro results with the same material produced mineralized collagen fibers with a similar morphology and chemical characteristics, suggesting that amide hydrolysis may have introduced into this matrix, signs for the controlled mineralization of collagen fiber . TEM indicated that amide hydrolysis occurred near the OVERLAP and GAP zones, as suggested by the significant reduction in inter-band distances in these regions . The lack of an inflammatory response associated to the similar mineralization pattern observed in vivo and in vitro suggests not only the biomimetic behavior of polyanionic collagen matrix, but also its potential uses as scaffold for bone tissue reconstruction . Based on these results, a model for the in vitro mineralization was also proposed.

Adv Biochem Eng Biotechnol, 2003, 82, 69 - 134
Potential for anaerobic conversion of xenobiotics; Mogensen AS et al.; This review covers the latest research on the anaerobic biodegradation of aromatic xenobiotic compounds, with emphasis on surfactants, polycyclic aromatic hydrocarbons, phthalate esters, polychlorinated biphenyls, halogenated phenols, and pesticides . The versatility of anaerobic reactor systems regarding the treatment of xenobiotics is shown with the focus on the UASB reactor, but the applicability of other reactor designs for treatment of hazardous waste is also included . Bioaugmentation has proved to be a viable technique to enhance a specific activity in anaerobic reactors and recent research on reactor and in situ bioaugmentation is reported.

J Contam Hydrol, 2003 Jun, 64(1-2), 59 - 72
In situ biodegradation determined by carbon isotope fractionation of aromatic hydrocarbons in an anaerobic landfill leachate plume (Vejen, Denmark); Richnow HH et al.; Concentrations and isotopic compositions (13C/12C) of aromatic hydrocarbons were determined in eight samples obtained from the strongly anoxic part of the leachate plume downgradient from the Vejen Landfill (Denmark), where methanogenic, sulfate-reducing and iron-reducing conditions were observed . Despite the heterogeneous distribution of the compounds in the plume, the isotope fractionation proved that ethylbenzene and m/p-xylene were subject to significant biodegradation within the strongly anoxic plume . The isotope fractionation factors (alphaC) for the degradation of the m/p-xylene (1.0015) and ethylbenzene (1.0021) obtained from the field observations were similar to factors previously determined for the anaerobic degradation of toluene and o-xylene in laboratory experiments, and suggest that in situ biodegradation is one major process controlling the fate of these contaminants in this aquifer . The isotope fractionation determined for 1,2,4-trimethylbenzene and 2-ethyltoluene suggested in situ biodegradation; however, the isotopic composition did not correlate well with the respective concentration as expressed by the Rayleigh equation . Some other compounds (1,2,3-trimethylbenzene, o-xylene, naphthalene and fenchone) did not show significant enrichments in delta13C values along the flow path . The compound concentrations were too low for accurate isotope analyses of benzene, toluene, 1- and 2-methylnaphthalene, while interferences in the chromatography made it impossible to evaluate the isotopic composition for 4-ethyltoluene, 1,3,5-trimethylbenzene and camphor.In addition to demonstrating the potential of assessing isotopic fractionation as a means for documenting the in situ biodegradation of complex mixtures of aromatic hydrocarbons in leachate plumes, this study also illustrates the difficulties for data interpretation in complex plumes and high analytical uncertainties for isotope analysis of organic compounds in low concentration ranges.

Sheng Wu Yi Xue Gong Cheng Xue Za Zhi, 2003 Mar, 20(1), 143 - 7
{Researches on PEG-modified copolymer nanoparticle}; Chen W et al.; Biodegradable polymeric nanoparticles acting as drug carrier have important potential applications such as site-specific drug delivery and controllable drug delivery . However, these carriers cannot generally be used because they are eliminated by the reticulo-endothelial system within seconds or minutes after intravenous injection . To overcome this limitation, more and more researchers introduce hydrophilic polyethylene glyeol(PEG) to modify polymeric nanoparticles for avoiding their uptake by reticulo-endothelial system . Introducing PEG not only changes polymer nanoparticles' biodegradation in vivo, but also influences drug's properties such as drug release, in vivo biodistribution, et . al . In this paper are reviewed the researches of PEG-modified copolymer nanoparticles, including their preparation and size distribution, stability, drug incorporation, drug release, in vivo biodistribution, in vitro cytotoxicty . A prospect for the researches and developments of the PEG-modified copolymer nanoparticles was also made.

Appl Microbiol Biotechnol, 2003 May, 61(4), 380 - 3 Epub 2003 Mar 14.
Biodegradation of chloronaphthalenes and polycyclic aromatic hydrocarbons by the white-rot fungus Phlebia lindtneri; Mori T et al.; The biodegradation of chloronaphthalene (CN) and polycyclic aromatic hydrocarbons by the white-rot fungus Phlebia lindtneri, which can degrade dichlorinated dioxins and non-chlorinated dioxin-like compounds, was investigated . Naphthalene, phenanthrene, 1-chloronaphthalene (1-CN) and 2-chloronaphthalene (2-CN) were metabolized by the fungus to form several oxidized products . Naphthalene and phenanthrene were metabolized to the corresponding hydroxylated and dihydrodihydroxylated metabolites . 2-CN was metabolized to 3-chloro-2-naphtol, 6-chloro-1-naphtol and two other chloronaphtols, CN-dihydrodiols and CN-diols . Significant inhibition of the degradation of these substrates was observed when they were incubated with the cytochrome P-450 monooxygenase inhibitors 1-aminobenzotriazole and piperonyl butoxide . These results suggest that P . lindtneri initially oxidizes these substrates by a cytochrome P-450 monooxygenase.

Appl Microbiol Biotechnol, 2003 May, 61(4), 342 - 51 Epub 2003 Feb 11.
Biodegradation of phenanthrene by Pseudomonas sp . strain PP2: novel metabolic pathway, role of biosurfactant and cell surface hydrophobicity in hydrocarbon assimilation; Prabhu Y et al.; Pseudomonas sp . strain PP2 isolated in our laboratory efficiently metabolizes phenanthrene at 0.3% concentration as the sole source of carbon and energy . The metabolic pathways for the degradation of phenanthrene, benzoate and p-hydroxybenzoate were elucidated by identifying metabolites, biotransformation studies, oxygen uptake by whole cells on probable metabolic intermediates, and monitoring enzyme activities in cell-free extracts . The results obtained suggest that phenanthrene degradation is initiated by double hydroxylation resulting in the formation of 3,4-dihydroxyphenanthrene . The diol was finally oxidized to 2-hydroxymuconic semialdehyde . Detection of 1-hydroxy-2-naphthoic acid, alpha-naphthol, 1,2-dihydroxy naphthalene, and salicylate in the spent medium by thin layer chromatography; the presence of 1,2-dihydroxynaphthalene dioxygenase, salicylaldehyde dehydrogenase and catechol-2,3-dioxygenase activity in the extract; O(2) uptake by cells on alpha-naphthol, 1,2-dihydroxynaphthalene, salicylaldehyde, salicylate and catechol; and no O(2) uptake on o-phthalate and 3,4-dihydroxybenzoate supports the novel route of metabolism of phenanthrene via 1-hydroxy-2-naphthoic acid --> {alpha-naphthol} --> 1,2-dihydroxy naphthalene --> salicylate --> catechol . The strain degrades benzoate via catechol and cis,cis-muconic acid, and p-hydroxybenzoate via 3,4-dihydroxybenzoate and 3-carboxy- cis,cis-muconic acid . Interestingly, the culture failed to grow on naphthalene . When grown on either hydrocarbon or dextrose, the culture showed good extracellular biosurfactant production . Growth-dependent changes in the cell surface hydrophobicity, and emulsification activity experiments suggest that: (1) production of biosurfactant was constitutive and growth-associated, (2) production was higher when cells were grown on phenanthrene as compared to dextrose and benzoate, (3) hydrocarbon-grown cells were more hydrophobic and showed higher affinity towards both aromatic and aliphatic hydrocarbons compared to dextrose-grown cells, and (4) mid-log-phase cells were significantly (2-fold) more hydrophobic than stationary phase cells . Based on these results, we hypothesize that growth-associated extracellular biosurfactant production and modulation of cell surface hydrophobicity plays an important role in hydrocarbon assimilation/uptake in Pseudomonas sp . strain PP2.

Biomaterials, 2003 Aug, 24(17), 2805 - 19
Isolation of methylene dianiline and aqueous-soluble biodegradation products from polycarbonate-polyurethanes; Tang YW et al.; Polycarbonate-polyurethanes (PCNUs) have provided the medical device industry with practical alternatives to oxidation-sensitive polyether-urethanes (PEUs) . To date, many studies have focused on PCNUs synthesized with 4,4'-methylene diphenyl-diisocyanate (MDI) . The relative hydrolytic stability of this class of polyurethanes is actually quite surprising given the inherent hydrolytic potential of the aliphatic carbonate group . Yet, there has been little information reporting on the rationale for the material's demonstrated hydrolytic stability . Recent work has shown that PCNU materials have a strong sensitivity towards hydrolysis when changes are made to their hard segment content and/or chemistry . However, knowledge is specifically lacking in regards of the identification of cleavage sites and the specific nature of the biodegradation products . Using high-performance liquid chromatography, radiolabel tracers and mass spectrometry, the current study provides insight into the distribution of biodegradation products from the enzyme-catalyzed hydrolysis of five different PCNUs . The hydrolytic sensitivity of the materials is shown to be related to the distribution of products, which itself is a direct consequence of unique micro-structures formed within the different materials . While an MDI-based polymer was shown to be the most hydrolytically stable material, it was the only PCNU that produced its diamine analog, in this case 4,4'-methylene dianiline (MDA), as a degradation product . Given the concern over aromatic diamine toxicity, this finding is important and highlights the fact that relative biostability is a distinct issue from that of degradation product toxicity, and that both must be considered separately when assessing the impact of biodegradation on biomaterial in vivo compatibility.

Appl Microbiol Biotechnol, 2003 Oct, 62(5-6), 557 - 63 Epub 2003 May 10.
Utilisation of structurally diverse organophosphonates by Streptomycetes; Obojska A et al.; A group of streptomycete strains was found able to utilise a wide range of structurally diverse phosphonates as a sole phosphorus source . No relation could be observed between ability to synthesise compounds containing a direct carbon-to-phosphorus (C-P) bond and biodegradative potential towards phosphonates in the strains studied . Streptomyces morookaensis DSM 40565 could degrade 2-amino-4-phosphonobutyrate as a sole nitrogen and phosphorus source in a stereoselective-like manner . This result suggests the existence of a new metabolic pathway for C-P bond breakage.

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