Biodegradation

Waste Manag Res, 2003 Apr, 21(2), 119 - 26
Modelling simplification of landfill processes by using methods of reliability theory; Hosser D et al.; By the year 2005 most landfills in Germany will be closed down and begin the closing phase and later the after-care phase . So far there have been only a few scientific investigations concerning the hazard potential of stored waste for the environment . For this reason, it is necessary to predict how the hazard potential of landfills will vary after closure . The prediction can be made by describing the coupled processes of biodegradation and pollutant transport using models that are currently being developed . These models deal with highly non-linear differential equations having a large number of parameters . In order to permit application of the model in practice, it is necessary to reduce these to parameters which are essential to the reliability of the landfill . They have to be identified by sensitivity investigations with the aid of methods of reliability theory so that models can be limited to these essential parameters and the calculation effort as well as measurement of parameters (monitoring) can be considerably reduced.

Chemosphere, 2003 Jul, 52(4), 673 - 82
Biodegradation of phthalate esters during the mesophilic anaerobic digestion of sludge; Gavala HN et al.; Phthalic acid esters (PAE) are commonly found in the sludge generated in the wastewater treatment plants . Anaerobic digestion followed by land application is a common treatment and disposal practice of sludge . To date, many studies exist on the anaerobic biodegradation rates of PAE, especially of the easily biodegradable ones, whereas the higher molecular weight PAE have reported to be non-biodegradable under methanogenic conditions . Furthermore, there is no information on the effect of the PAE on the performance of the anaerobic digesters treating sludge . In this study, the anaerobic biodegradation of di-n-butyl phthalate (DBP), di-ethyl phthalate (DEP) and di-ethylhexyl phthalate (DEHP) was investigated and their relative rates of anaerobic degradation were calculated . Also, the biological removal of PAE during the anaerobic digestion of sludge in bench-scale digesters was investigated using DBP and DEHP as model compounds of one biodegradable and one recalcitrant PAE respectively . The degradation of all the PAE tested in this study (DEP, DBP and DEHP) is adequately described by first-order kinetics . Batch and continuous experiments showed that DEP and DBP present in sludge are rapidly degraded under mesophilic anaerobic conditions (a first-order kinetic constant of 8.04 x 10(-2) and 13.69 x 10(-2)-4.35 day(-1) respectively) while DEHP is degraded at a rate between one to two orders of magnitude lower (0.35 x 10(-2)-3.59 x 10(-2) day(-1)) . It is of high significance that experiments with anaerobic sludge of different origin (US and Europe) showed that degradation of DEHP occurs under methanogenic conditions . Accumulation of high levels of DEHP (more than 60 mg/l) in the anaerobic digester has a negative effect on DBP and DEHP removal rates as well as on the biogas production.

Chemosphere, 2003 Jul, 52(2), 437 - 42
Uptake, translocation and fate of trichloroacetic acid in a Norway spruce/soil system; Schroder P et al.; Trichloroacetic acid (TCA) is a secondary atmospheric pollutant formed by photooxidation of chlorinated solvents in the troposphere--it has, however, recently been ranked among natural organohalogens . Its herbicidal properties might be one of the factors adversely affecting forest health . TCA accumulates rapidly in conifer needles and influences the detoxification capacity in the trees . The aim of the investigations--a survey of which is briefly given here--was to elucidate the uptake, distribution and fate of TCA in Norway spruce . For this purpose young nursery-grown plants of Norway spruce (Picea abies (L.) Karst.) were exposed to {1,2-14C}TCA and the fate of the compound was followed in needles, wood, roots, soil and air with appropriate radio-indicator methods . As shown by radioactivity monitoring, the uptake of TCA from soil by roots proceeded most rapidly into current needles at the beginning of the TCA treatment and was redistributed at later dates so that TCA content in older needles increased . The only product of TCA metabolism/biodegradation found in the plant/soil-system was CO(2) (and corresponding assimilates) . TCA biodegradation in soil depends on TCA concentration, soil humidity and other factors.

J Biomed Mater Res A, 2003 May 1, 65(2), 170 - 81
Coaxial double-tubular compliant arterial graft prosthesis: time-dependent morphogenesis and compliance changes after implantation; Sonoda H et al.; In order to reduce the compliance mismatch between the native artery and the artificial graft, we have developed a coaxial double-tubular compliant graft, using multiply micropored segmented polyurethane (SPU) thin films, which mimics the relationship between the intraluminal pressure and vessel internal diameter (P-D) of the native artery (termed "J" curve) . The graft was coaxially assembled by inserting a high-compliance inner tube with a heparin-immobilized photocured gelatin coating layer into a low-compliance outer tube with a photocured hydrophilic polymer coating layer . Twenty-eight coaxial double-tubular compliant grafts were implanted into the canine common carotid arteries in an end-to-end fashion for up to 12 months . The overall patency rate was 86% (24/28), and neither rupture nor aneurysmal formation was observed . A neoarterial wall was formed via transanastomotic and transmural tissue ingrowth, resulting in neoarterial tissue formation on the luminal surface and into the intertubular space of the double-tubular graft, accompanied by mainly myofibroblasts and inflammatory cells in the early stage and endothelialization and collagen-rich extracellular matrices in the late stage of implantation . Surrounding-tissue adhesion with the outer tube was prevented by the hydrophilic polymer coating . Although the J curve of the implanted prototype model was preserved 1 month after implantation, the impaired J curves were observed because of tissue ingrowth and tissue adhesion between the outer surface of the inner tube and the surrounding tissues 3 and 6 months after implantation . At 12 months after implantation, however, the implanted coaxial double-tubular graft exhibited high compliance due to biodegradation of the SPU films .

Bioresour Technol, 2003 Mar, 87(1), 81 - 6
Biodegradation of hexadecane in liquid and solid-state fermentations by Aspergillus niger; Volke-Sepulveda TL et al.; The biodegradation and mineralisation of hexadecane (HXD) by Aspergillus niger were studied in SmF and Solid-state fermentation (SSF) . HXD concentrations ranging from 45 to 180 g/l (SSF) and from 20 to 80 g/l (SmF) were tested . HXD consumption was three times higher and fungal growth was up to 30 times faster in SSF than in SmF . The maximum HXD consumption in SmF was 62% (18% mineralised) and in SSF 100% (52% mineralised) for initial HXD concentrations of 20 and 45 g/l, respectively . The respiratory quotient in SmF increased (from 0.85 to 1.08) with increase in HXD concentration, while it was independent (approximately 0.68) of the initial HXD concentration in SSF . These results showed that the consumption rate and biodegradation efficiency for HXD were higher in SSF than in SmF.

Curr Microbiol, 2003 May, 46(5), 371 - 9
Function of a low molecular weight peptide from Trichoderma pseudokoningii S38 during cellulose biodegradation; Wang W et al.; The biochemical mechanism for cellulose decomposition by a low molecular weight peptide, named short fiber generating factor (SFGF), derived from the culture supernatant of a cellulolytic fungus Trichoderma pseudokoningii S-38, was determined . Sufficient information obtained by biochemical and biophysical studies and combined with observation with a scanning electron microscope provided further evidence for the earlier studies that the SFGF had a high capacity for chelating and reducing ferric ions, and could produce free radical by reduction of Fe(3+) to Fe(2+) in the presence of oxygen molecule . These studies suggested that the effect of SFGF on cellulose is directly related to an oxidative reaction and is different from the hydrolysis of cellulose by cellulases . The alcoholic hydroxyl groups in cellulose can be oxidized by SFGF, which leads to destruction of the hydrogen bond network in cellulose and cleavage of glycosidic linkages . Both effects led to the de-polymerization of cellulose and the formation of short fibers, and increase of reducing groups in residual cellulose, then the cellulose substrates became more susceptible for hydrolysis by cellulases.

Environ Sci Technol, 2003 Apr 15, 37(8), 1545 - 52
Intra-aggregate mass transport-limited bioavailability of polycyclic aromatic hydrocarbons to Mycobacterium strain PC01; Shor LM et al.; Biodegradation kinetics for three- and four-ring PAHs by Mycobacterium sp . strain PC01 were measured in whole and density-fractionated estuarine sediments and in a system without intra-aggregate mass transport limitations . The biokinetic data in the systems with and without intra-aggregate mass transport limitations were compared with abiotic PAH desorption kinetics . The results indicate that intra-aggregate mass transport limitations, and not the intrinsic bacterial PAH utilization capacity, were most important in controlling the rate of biodegradation of sediment-sorbed PAHs . Achievable extent of biodegradation could be predicted by the independently measured traction of desorbable PAHs in the fast-diffusion regime of a two-domain intra-aggregate mass transport model . A closed-form mathematical model was developed to describe sediment-pore water partitioning and rapid aqueous-phase diffusion of PAHs through the macropore and mesopore network of sediment aggregates, followed by first-order biodegradation of desorbed PAHs in the bulk aqueous domain . The model effectively predicted independent biodegradation kinetics of PAHs field-aged in two estuarine sediments . Despite low aqueous solubility of PAHs, macropore and mesopore diffusion may be an important mechanism controlling intra-aggregate mass transport and bioavailability of the most readily and extensively desorbed PAHs in sediments.

Biosci Biotechnol Biochem, 2003 Feb, 67(2), 225 - 43
Genetics of polycyclic aromatic hydrocarbon metabolism in diverse aerobic bacteria; Habe H et al.; Polycyclic aromatic hydrocarbons (PAHs), which consist of two or more fused aromatic rings, are widespread in the environment and persist over long periods of time . The decontamination of a PAH-polluted environment is of importance because some PAHs are toxic, mutagenic, and carcinogenic and therefore are health hazards . As part of the efforts to establish remediation processes, the use of aerobic bacteria has been extensively studied, and both enzymologic and genetic studies are underway for the purpose of effective biodegradation . In the last two decades, one highly conserved group of PAH-catabolic genes from Pseudomonas species, called the nah-like genes, has been well investigated, and much has been found, including the structure-function relationships and the evolutionary trails of the catabolic enzymes . However, recently, PAH-catabolic genes, which are evolutionarily different from the nah-like genes, have been characterized from both Gram-negative bacteria other than Pseudomonas species and Gram-positive bacteria, and the information about these genes is expanding . This review is an outline of genetic knowledge about bacterial PAH catabolism.

Biodegradation, 2002, 13(6), 395 - 9
Biodegradation of glucosinolates in brown mustard seed meal (Brassica juncea) by Aspergillus sp . NR-4201 in liquid and solid-state cultures; Rakariyatham N et al.; Aspergillus sp . NR-4201 was assessed by degrading glucosinolates in brown mustard seed meal (Brassica juncea) . A liquid culture of the strain, in a medium derived from the meal, produced total degradation of glucosinolates at 32 h . Under these conditions, the glucosinolate-breakdown product, allylcyanide, was formed in culture filtrates . In a plate culture under sterile conditions, the growth of the strain in heat-treated meal media was shown to be effective at 30 degrees C with 51% moisture, as determined by the measurement of the colony growth rate . On the laboratory scale, solid-state culture under the same conditions gave rise to total glucosinolate degradation within 48 h . In comparison, under non-sterile conditions in either heat-treated or non heat-treated meal samples, the degradations were complete after 60 and 96 h, respectively . In these cases, growth was associated with some out-growths of contaminating fungi, mainly Rhizopus sp . and Mucor sp . The glucosinolate-breakdown product, allylcyanide, was not detected in the solid-state meal-media culture presumably due to evaporative loss from the fermentation matrix.

Biomaterials, 2003 Jul, 24(16), 2779 - 87
Bio-compatibility of type I/III collagen matrix for peripheral nerve reconstruction; Keilhoff G et al.; Nerve gaps are usually bridged by autografts . With improving technical methods biocompatible conduits may become an alternative graft to reconstruct nerves . Non-neural conduits fail to support regeneration over larger gaps due to lacking viable Schwann cells . Thus, tissue engineering of nerves is focusing on implantation of viable Schwann cells into suitable scaffolds . In this study, we tested collagen type I/III tubes as a potential nerve guiding matrix . Revascularization, foreign body reaction, biodegradation and Schwann cell settlement were evaluated by immunocytochemistry, light, fluorescence and scanning electron microscopy, after different implantation times . The conduits were completely revascularized between day 5 and 7 post-operatively and well integrated into the host tissue . Host response was characterized by a moderate invasion of ED1/ED2-positive macrophages . Biodegradation of the tubes was slowly enough to maintain a stable support structure for extended regeneration processes . Implanted Schwann cells adhered, survived and proliferated on the inner surface of the conduits and were able to form nerve guiding columns of Bungner . From this results, we conclude that collagen-type I/III can serve as template to design "living" nerve conduits, which may be able to ensure nerve regeneration through extended nerve gaps.

Biomaterials, 2003 Jul, 24(16), 2773 - 8
Thermal and mechanical characteristics of poly(L-lactic acid) nanocomposite scaffold; Lee JH et al.; Inorganic nanosized silicate nanoplatelets were incorporated into biodegradable poly(L-lactic acid) (PLLA) for the purpose of tailoring mechanical stiffness of PLLA porous scaffold systems . Increasing the nucleation density around the foreign body surfaces, the montmorillonite (MMT) nanoplatelets modified with dimethyl dihydrogenated tallow ammonium cations decreased the glass transition temperature and the degree of PLLA crystallinity, which seemingly caused the accelerated biodegradation rate of PLLA nanocomposites due to the enhanced segmental mobility of backbone chains and the expanded amorphous region of PLLA matrix . The tensile modulus was increased from 121.2MPa of pristine polymer scaffold to 170.1MPa of MMT/PLLA nanocomposite scaffold (ca . 40% increment) by the addition of small amount of MMT platelets (5.79 vol%) acting as a mechanical reinforcement of polymer chains in the nanoscale molecular level . Overall, the nanotechnology used in this study may be applied to various scaffold systems of biodegradable polymers and hard/soft scaffold structures requiring critical control and design characteristics of mechanical stiffness and biodegradation rate.

Environ Int, 2003 Jul, 29(4), 459 - 65
Aerobic degradation of 2,4,6-TCP content in ECF bleached effluent; Correa J et al.; Elemental chlorine-free (ECF) bleach effluents from kraft mill are characterised by: a chemical organic demand/biological organic demand (COD/BOD(5)) ratio of 4, chlorophenol content with low chlorine substitution, and toxicity . The effect of increasing the concentration of 2,4,6-trichlorophenol (2,4,6-TCP) content in ECF bleaching sequence effluent on the degradative activity of bacterial communities present in an aerobic system treatment was studied . An aerobic lagoon (AL) was used as a typical secondary treatment of kraft-mill effluent . AL displays a high performance of BOD(5) degradation (up to 90%); however, only 40% of the COD was removed . Simultaneously, the AL system shows a high ability to biodegrade 2,4,6-TCP up to 237 mg/l day . Kinetic parameters of the 2,4,6-TCP biodegradation by aerobic bacteria were determined . The K(s) and K(i) values were 34.3 and 50 mg/l 2,4,6-TCP, respectively . Moreover, the tolerance of aerobic bacteria was observed up to 1.3 g/l 2,4,6-TCP.

Mar Pollut Bull, 2003 Apr, 46(4), 418 - 23
Biodegradation of toxic chemicals in Guayanilla Bay, Puerto Rico; Zaidi BR et al.; Studies were conducted to assess the factors that may influence the rate and extent of biodegradation of biphenyl, naphthalene, phenanthrene, pentachlorophenol (PCP) and p-nitrophenol in water samples collected from the Guayanilla Bay (18 degrees N; 67.45 degrees W), southwest of Puerto Rico . In vitro studies mediated slow degradation of biphenyl, naphthalene and phenanthrene substrates by natural microbial flora present in the Bay . Addition of KNO(3) as a source of inorganic N greatly enhanced the degradation of phenanthrene but not of naphthalene, suggesting that effects on degradation due to nutrient limitation were compound specific . The rate and extent of degradation of naphthalene and PCP were higher in water samples collected closer to the source of contamination, i.e . the petrochemical complex . The identity of a phenanthrene degrading bacterium, previously identified by conventional phenotypic method (Zaidi et al., Utilizing Nature's Advanced Materials, Oxford Unviersity Press, 1999) as Alteromonas sp., was confirmed by partial DNA sequencing of the small subunit rRNA gene.

Biomaterials, 2003 Jun, 24(13), 2309 - 16
Cell sheet engineering for myocardial tissue reconstruction; Shimizu T et al.; Myocardial tissue engineering has now emerged as one of the most promising treatments for the patients suffering from severe heart failure . Tissue engineering has currently been based on the technology using three-dimensional (3-D) biodegradable scaffolds as alternatives for extracellular matrix . According to this most popular technique, several types of 3-D myocardial tissues have been successfully engineered by seeding cardiomyocytes into poly(glycolic acid), gelatin, alginate or collagen scaffolds . However, insufficient cell migration into the scaffolds and inflammatory reaction due to scaffold biodegradation remain problems to be solved . In contrast to these technologies, we now propose novel tissue engineering methodology layering cell sheets to construct 3-D functional tissues without any artificial scaffolds . Confluent cells on temperature-responsive culture surfaces can be harvested as a viable contiguous cell sheet only by lowering temperature without any enzymatic digestions . Electrical communications are established between layered cardiomyocyte sheets, resulting in simultaneous beating 3-D myocardial tissues . Layered cardiomyocyte sheets in vivo present long survival, macroscopic pulsation and characteristic structures of native heart tissue . Cell sheet engineering should have enormous potential for fabricating clinically applicable myocardial tissues and should promote tissue engineering research fields.

Water Res, 2003 Apr, 37(8), 1729 - 36
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 evaluated using model reactors to clarify the effects of non-aqueous phase liquid (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 of acenaphtene and phenanthrene due to the smaller dissolution rates . Dissolution rates of PAHs in fuel oil C were smaller than those in crude oil due to high viscosity of fuel oil C . Hence, biodegradation rates of PAHs in fuel oil C were smaller than those in crude oil . Biodegradation rates of PAHs in NAPL with slow rate of decrease like fuel oil C was slower than those in NAPL with rapid rate of decrease like crude oil . The smaller rate of decrease of fuel oil C than crude oil was due to the higher viscosity of fuel oil C . Therefore, not only the dissolution rate of PAHs but also the rates of decrease of NAPL were important factors for the biodegradation of PAHs.

Biomaterials, 2003 Jun, 24(14), 2549 - 57
In vivo biostability of a poly(carbonate-urea)urethane graft; Seifalian AM et al.; In peripheral and coronary bypass surgery, the patency of prosthetic grafts is inferior to autologous vein, mainly due to intimal hyperplasia caused in part by compliance mismatch between rigid graft and elastic host artery . We have developed a compliant poly(carbonate-urea)urethane vascular graft "MyoLink" which was biostable in vitro degradation studies . To further investigate the biostability of this material, we report a long-term in vivo study on 8 beagle dogs (15+/-3 kg) implanted with this graft (ID 5mm) in the aorta-iliac position; three grafts were harvested at 18 months to assess short-term biodegradation, with one animal having died from an unrelated infection . The 4 remaining grafts were harvested at 36 months for analysis by: (1) histology, (2) compliance measurements and (3) environmental scanning electron microscopy (ESEM); gel permeation chromatography (GPC); attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) and radial tensile strength analysis.There was no infection or inflammation of the grafts or surrounding tissues . Histological analysis showed a well-developed neointima but only at the distal anastomosis . There were no significant differences in compliance pre- and post-implantation and no evidence of material curvature, radial expansion or chemical breakdown, ESEM and GPC showed no signs of degradation . Peak height analysis with ATR-FTIR of the 1740 cm(-1) (C=O of carbonate) and 1253 cm(-1) bands (C-O-C of CO-O-C) showed a loss of carbonate carbonyl but was not statistically significant . Radial tensile strength remained within batch release specifications.This polyurethane graft retains its compliance post-implantation, whilst exhibiting only a minor hydrolysis of the amorphous segment, confirming its biostability in vivo up to 3 years.

Biomaterials, 2003 Jun, 24(14), 2497 - 502
A biodegradable fibrin scaffold for mesenchymal stem cell transplantation; Bensaid W et al.; A potential therapy to enhance healing of bone tissue is to deliver isolated mesenchymal stem cells (MSCs) to the site of a lesion to promote bone formation . A key issue within this technology is the development of an injectable system for the delivery of MSCs . Fibrin gel exploits the final stage of the coagulation cascade in which fibrinogen molecules are cleaved by thrombin, convert into fibrin monomers and assembled into fibrils, eventually forming fibers in a three-dimensional network . This gel could have many advantages as a cell delivery vehicle in terms of biocompatibility, biodegradation and hemostasis . The objective of this study was to explore the possibility of using fibrin gel as a delivery system for human MSCs (HMSCs) . To this end we have determined the optimal fibrinogen concentrations and thrombin activity for loading HMSCs in vitro into the resultant fibrin gels to obtain cell proliferation . We found that a concentration of 18 mg/ml of fibrinogen and a thrombin activity of 100 IU/ml was optimal for producing fibrin scaffolds that would allow good HMSCs spreading and proliferation . In these conditions, cells were able to proliferate and expressed alkaline phosphatase, a bone marker, in vitro . When implanted in vivo, HMSCs were able to migrate out of the fibrin gel and invade a calcium carbonate based ceramic scaffold suggesting that fibrin gel could serve as a delivery system for HMSCs.

FEMS Microbiol Lett, 2003 Apr 11, 221(1), 111 - 7
Isolation and characterisation of Nocardioides sp . SP12, an atrazine-degrading bacterial strain possessing the gene trzN from bulk- and maize rhizosphere soil; Piutti S et al.; We report the characterisation of Nocardioides sp . SP12, an atrazine-degrading bacteria isolated from atrazine-treated bulk- and maize rhizosphere soil . Based on 16S rDNA alignment, strain SP12 showed close phylogenic relationships with Nocardioides sp . C157 and Nocardioides simplex . Internal transcribed spacer (ITS) sequences of strain SP12 were longer than those of other Nocardioides sp . and present Ala- and Ile-tRNA unlike Actinomycetales . Nocardioides sp . SP12 presents a novel atrazine catabolic pathway combining trzN with atzB and atzC . Atrazine biodegradation ends in a metabolite that co-eluted in HPLC with cyanuric acid . This metabolite shows an absorption spectrum identical to that of cyanuric acid with a maximal absorption at 214.6 nm . The mass of the atrazine metabolite is in concordance with that of cyanuric acid according to mass spectrometry analysis . Quantitative PCR revealed that the ITS sequence of Nocardioides sp . SP12 was at a lower number than the one of trzN in atrazine-treated soil samples . It suggests that trzN could also be present in other atrazine degrading bacteria . The numbers of trzN and ITS sequences of Nocardioides sp . SP12 were higher in the maize rhizosphere than in bulk soil.

Water Res, 2003 May, 37(9), 2149 - 61
Source apportionment of PAHs in dated sediments from the Black River, Ohio; Gu SH et al.; Black River, OH, is contaminated with polycyclic aromatic hydrocarbons (PAHs) from coke ovens of a US Steel Corp . Plant . Closing of a coking plant in 1983 and environmental dredging of the sediments during 1989 and 1990 has reduced the PAH levels significantly . This study quantifies the decrease, and consider source apportionment of PAHs in Black River sediments using chemical mass balance modeling . Five vibra cores collected in 1998 and dated using 210Pb and 137Cs, were analyzed for 18 PAHs . The cores had total PAH concentrations between 250 and 0.10 ppm . PAH maxima occur in 1949, 1969, in accordance with regional historical inputs (core BR4), and in 1991 due to remediation (BR6) . Coke oven emissions (CO), highway dust (HWY), and wood burning (WB) are likely sources . The CO source (6-92% of total PAHs) is maximal in 1954, and again in 1992-1994 due to the exposure and redistribution of older contaminated sediments during dredging, and decreases thereafter . There is minimal CO content in 1985 (BR4), 2 yr after closure of the coking plant . The HWY contribution (2-86%) is high during 1969-1988, and increases again after 1993 . The WB source is less than 23%, and exhibits a minimum (2%) around 1979 (BR4) . There is evidence of aerobic biodegradation or photolysis in the sediment of phenanthrene (PhA) at PhA concentrations >500 ppb.

Biodegradation, 2002, 13(5), 297 - 305
Mechanism of aerobic transformation of carbon tetrachloride by poplar cells; Wang X et al.; The biochemical mechanism of carbon tetrachloride transformation by poplar cells was investigated using an axenic poplar cell culture . After one-day incubations of poplar cells under aerobic conditions, about 1.5% of dosed carbon tetrachloride was transformed to carbon dioxide, about 0.001% to chloroform and about 3% of the carbon was bound to insoluble poplar cellular materials . The production of carbon dioxide increased under aerobic conditions while the formation of chloroform and cell binding of carbon tetrachloride-carbon was enhanced under anaerobic conditions . Both carbon dioxide production and cell binding were significantly inhibited by a general inhibitor of cytochrome P-450 activity (carbon monoxide) and by specific P-450 2E1 inhibitors (chlorzoxazone, isoniazid, 4-methylpyrazole and 1-phenylimidazole) . However, no inhibitory effects were observed when the cells were incubated in the presence of lignin peroxidase inhibitors (NaVO3 and 3-amino-1,2,4-triazole) . These results suggest that an enzyme similar to mammalian cytochrome P450-2E1 is involved in the metabolism of carbon tetrachloride by poplar cells . This study demonstrates an environmental biodegradative process for carbon tetrachloride that operates under aerobic conditions.

Environ Sci Technol, 2003 Mar 15, 37(6), 1061 - 8
Occurrence and fate of carbamazepine, clofibric acid, diclofenac, ibuprofen, ketoprofen, and naproxen in surface waters; Tixier C et al.; Although various single-concentration measurements of pharmaceuticals are available in the literature, detailed information on the variation over time of the concentration and the load in wastewater effluents and rivers and on the fate of these compounds in the aquatic environment are lacking . We measured the concentrations of six pharmaceuticals, carbamazepine, clofibric acid, diclofenac, ibuprofen, ketoprofen, and naproxen, in the effluents of three wastewater treatment plants (WWTPs), in two rivers and in the water column of Lake Greifensee (Switzerland) over a time period of three months . In WWTP effluents, the concentrations reached 0.95 microg/L for carbamazepine, 0.06 microg/L for clofibric acid, 0.99 microg/L for diclofenac, 1.3 microg/L for ibuprofen, 0.18 microg/L for ketoprofen, and 2.6 microg/L for naproxen . The relative importance in terms of loads was carbamazepine, followed by diclofenac, naproxen, ibuprofen, clofibric acid, and ketoprofen . An overall removal rate of all these pharmaceuticals was estimated in surface waters, under real-world conditions (in a lake), using field measurements and modeling . Carbamazepine and clofibric acid were fairly persistent . Phototransformation was identified as the main elimination process of diclofenac in the lake water during the study period . With a relatively high sorption coefficient to particles, ibuprofen might be eliminated by sedimentation . For ketoprofen and naproxen, biodegradation and phototransformation might be elimination processes . For the first time, quantitative data regarding removal rates were determined in surface waters under real-world conditions . All these findings are important data for a risk assessment of these compounds in surface waters.

Microbiology, 2003 Apr, 149(Pt 4), 903 - 13
Rational engineering of the regioselectivity of TecA tetrachlorobenzene dioxygenase for the transformation of chlorinated toluenes; Pollmann K et al.; The tetrachlorobenzene dioxygenase (TecA) of Ralstonia sp . PS12 carries out the first step in the aerobic biodegradation of chlorinated toluenes . Besides dioxygenation of the aromatic ring of 4-chloro-, 2,4-, 2,5- and 3,4-dichlorotoluene as the main reaction, it also catalyses mono-oxygenation of the methyl groups of 2,3-, 2,6-, 3,5-di- and 2,4,5-trichlorotoluene as the main reactions, channelling these compounds into dead-end pathways . Based on the crystal structure of the homologous naphthalene dioxygenase (NDO) and alignment of the alpha-subunits of NDO and TecA, the substrate pocket of TecA was modelled . Recently, for NDO and the homologous 2-nitrotoluene dioxygenase (2NTDO), two amino acids (Phe(352) of NDO and Asn(258) of 2NTDO) were identified which control the regioselectivity of these enzymes . The corresponding amino acids at Phe(366) and Leu(272) of TecA were substituted to change the regioselectivity and to expand the product spectrum . Position 366 was shown to control regioselectivity of the enzyme, although mutations resulted in decreased or lost activity . Amino acid substitutions at Leu(272) had little or no effect on the regioselectivity of TecA, but had significant effects on the product formation rate . Substitutions at both positions changed the site of oxidation of 2,4,5-trichlorotoluene slightly . As new products, 3,4,6-trichloro-1-methyl-1,2-dihydroxy-1,2-dihydrocyclohexan-3,5-diene, 4,6-dichloro-3-methylcatechol, 3,6-dichloro-4-methylcatechol and 3,4-dichloro-6-methylcatechol were identified.

Environ Toxicol Chem, 2003 Apr, 22(4), 837 - 44
Predicting ready biodegradability of premanufacture notice chemicals; Boethling RS et al.; Chemical substances other than pesticides, drugs, and food additives are regulated by the U.S . Environmental Protection Agency (U.S . EPA) under the Toxic Substances Control Act (TSCA), but the United States does not require that new substances be tested automatically for such critical properties as biodegradability . The resulting lack of submitted data has fostered the development of estimation methods, and the BioWIN models for predicting biodegradability from chemical structure have played a prominent role in premanufacture notice (PMN) review . Until now, validation efforts have used only the Japanese Ministry of International Trade and Industry (MITI) test data and have not included all models . To assess BioWIN performance with PMN substances, we assembled a database of PMNs for which ready biodegradation data had been submitted over the period 1995 through 2001 . The 305 PMN structures are highly varied and pose major challenges to chemical property estimation . Despite the variability of ready biodegradation tests, the use of at least six different test methods, and widely varying quality of submitted data, accuracy of four of six BioWIN models (MITI linear, MITI nonlinear, survey ultimate, survey primary) was in the 80+% range for predicting ready biodegradability . Greater accuracy (>90%) can be achieved by using model estimates only when the four models agree (true for 3/4 of the PMNs) . The BioWIN linear and nonlinear probability models did not perform as well even when classification criteria were optimized . The results suggest that the MITI and survey BioWIN models are suitable for use in screening-level applications.

Environ Toxicol Chem, 2003 Apr, 22(4), 699 - 705
Enhancement of aerobic microbial degradation of polychlorinated biphenyl in soil microcosms; Manzano MA et al.; This article reports the results of various biodegradation experiments on polychlorinated biphenyl (PCB)-contaminated sandy soil employing a mixed culture of acclimatized bacteria . Following the optimization of different variables without chemical pretreatment, the elimination rate achieved of Aroclor 1242 in slurry-phase reactors was 61% after four months of treatment, with the presence of biphenyl as cosubstrate being the most important factor affecting PCB biodegradation . The biodegradation occurred as a first-order process, and it proved most effective in respect to dichlorinated biphenyls (100% removal), followed by trichlorinated (92%) and tetrachlorinated biphenyls (24%) . The results also showed that the degradability of PCBs in soil may be enhanced by an advanced oxidation pretreatment (Fenton reaction), producing almost 100% elimination of PCBs at the end of the integrated chemical-biological process and 72% mineralization of the intermediates generated during the chemical pretreatment.

J Contam Hydrol, 2002 Nov, 59(1-2), 133 - 62
A case study for demonstrating the application of U.S . EPA's monitored natural attenuation screening protocol at a hazardous waste site; Clement TP et al.; Natural attenuation assessment data, collected at a Superfund site located in Louisiana, USA, are presented . The study site is contaminated with large quantities of DNAPL waste products . Source characterization data indicated that chlorinated ethene and ethane compounds are the major contaminants of concern . This case study illustrates the steps involved in implementing the U.S . EPA's {U.S . EPA, 1998 . Technical protocol for evaluating natural attenuation of chlorinated solvents in ground water, by Wiedmeier, T.H., Swnason, M.A., Moutoux, D.E., Gordon, E.K., Wilson, J.T., Wilson, B.H., Kampbell, D.H., Hass, P.E., Miller, R.N., Hansen, J . E., Chapelle, F.H., Office of Research and Development, EPA/600/R-98/128} monitored natural attenuation (MNA) screening protocol at this chlorinated solvent site . In the first stage of the MNA assessment process, the field data collected from four monitoring wells located in different parts of the plume were used to complete a biodegradation scoring analysis recommended by the protocol . The analysis indicates that the site has the potential for natural attenuation . In the second stage, a detailed conceptual model was developed to identify various contaminant transport pathways and exposure points . The U.S . EPA model and BIOCHLOR was used to assess whether the contaminants are attenuating at a reasonable rate along these transport paths so that MNA can be considered as a feasible remedial option for the site . The site data along with the modeling results indicate that the chlorinated ethene and chlorinated ethane plumes are degrading and will attenuate within 1000 ft down gradient from the source, well before reaching the identified exposure point Therefore, MNA can be considered as one of the feasible remediation options for the site.

J Contam Hydrol, 2002 Nov, 59(1-2), 113 - 31
Modelling of physical and reactive processes during biodegradation of a hydrocarbon plume under transient groundwater flow conditions; Prommer H et al.; Numerical experiments of non-reactive and reactive transport were carried out to quantify the influence of a seasonally varying, transient flow field on transport and natural attenuation at a hydrocarbon-contaminated field site . Different numerical schemes for solving advective transport were compared to assess their capability to model low transversal dispersivities in transient flow fields . For the field site, it is shown that vertical plume spreading is largely inhibited, particularly if sorption is taken into account . For the reactive simulations, a biodegradation reaction module for the geochemical transport model PHT3D was developed . Results of the reactive transport simulations show that under the site-specific conditions the temporal variations in groundwater flow do, to a modest extent, affect average biodegradation rates and average total (dissolved) contaminant mass in the aquifer . The model simulations demonstrate that the seasonal variability in groundwater flow only results in significantly enhanced biodegradation rates when a differential sorption of electron donor (toluene) and electron acceptor (sulfate) is assumed.

J Contam Hydrol, 2002 Nov, 59(1-2), 3 - 26
Persistence of LNAPL sources: relationship between risk reduction and LNAPL recovery; Huntley D et al.; Light nonaqueous phase liquids (LNAPLs), such as fuels, are the source of much soil and groundwater contamination . Though the mobility of LNAPLs is limited in many environments, dissolved-phase components, such as benzene, can produce groundwater plumes that are more mobile than the LNAPL source . In such a setting, it is commonly assumed that recovery of the LNAPL will result in a reduction in risk associated with the dissolved phase . This paper synthesizes several existing multiphase and chemical transport solutions into a single linked methodology that predicts concentrations of soluble constituents within and downgradient of LNAPL source zones from dissolution of those constituents into groundwater flowing through and below LNAPL sources . This approach has been applied to a variety of LNAPL spill conditions . For biodegradable compounds, these analyses show that the period of time where the dissolved-phase plume is expanding is very small compared to the duration of most LNAPL sources, and that the downgradient extent is generally less than about 100 m for BTEX compounds . Therefore, the risk to receptors, as measured by the maximum downgradient extent of dissolved-phase plume or the maximum concentration of these compounds at a downgradient receptor, is generally unrelated to the longevity of the LNAPL sources . The maximum downgradient extent of the dissolved-phase plume is determined almost entirely by the groundwater velocity and the biodegradation rate . These analyses further demonstrate that recovery of LNAPL by hydraulic methods is often ineffective at reducing risk . Except in coarse-grained soils or intermediate soils with significant LNAPL saturations, free-product recovery approaches do not result in significant reductions in the longevity of downgradient dissolved-phase contamination . Further, for biodegradable constituents, remediation does not result in a near-term decrease in the downgradient extent of contamination . Cleanup methods that act to change the composition of the LNAPL source are more effective at reducing the downgradient concentrations, particularly for fine-grained soils or when LNAPL saturations are low.

Vasa, 2003 Feb, 32(1), 31 - 5
Ultrastructural analysis of an infected collagen-coated vascular graft; Freytag CC et al.; The incidence of infection following arterial reconstruction using synthetic graft materials varies from less than 1 to 5% . One of three mechanisms is thought to be responsible: 1 . intraoperative contamination, 2 . extension from adjacent infected or colonized tissue, or 3 . hematogenous or lymphogenous seeding . We present ultrastructural data of a patient with a polymicrobial graft infection due to a prostheto-enteric fistula 16 years after reconstruction of an aortobifemoral graft . The polymer surface showed signs of biodegradation and was completely covered with a layer of plasma proteins . Disrupted fibroblasts on the intersegmental graft surface were surrounded by bundles of collagen . Gram-negative rods and grampositive cocci were embedded in an extracellular EPS matrix . Bacterial culture confirmed growth of Eikenella corrodens, Fusobacterium nucleatum and Peptostreptococcus species . Fibrin and granulation tissue from the neoadventitia started to mark off the inflammatory process . Transmission electron microscopy is a valuable tool for the investigation of alloplastic arterial devices . After 16 years of implantation the graft shows different signs of biodegradation.

Polim Med, 2002, 32(3-4), 40 - 7
Molecular and clinical consequences of in vivo silicones biodegradation; Lukasiak J et al.; The object of the publication is the presentation of data referring to in vivo silicones biodegradation and their potential clinical and molecular consequences . Summing up, one needs to state that the products of silicones biodegradation are not biologically indifferent . In particular, different types of silanols are inhibitors of proteolytic enzymes and regulators of many metabolic processes as well as affect the cell growth and division, which distinctly indicates the potentially strong pharmacological action . The main objective of the molecular consequences of the biodegradation of siloxanes was the verification what impact siloxanes of various molecular weights and of various chain lengths exert on the conformational stability of biological molecules.

J Environ Biol, 2002 Oct, 23(4), 365 - 71
Biodegradation of wastewater of Najafgarh drain, Delhi using autochthonous microbial consortia : a laboratory study; Sharma G et al.; There are seventeen drains, which discharge their untreated urban and industrial wastewaters into the Delhi segment of river Yamuna . The Najafgarh drain is the first and the largest drain, and it alone contributes 1667.84 mld i.e . 60% of the total wastewater discharge into the river Yamuna and as such add 81.36 tons of BOD load per day . As per the available data approximately 95% of the wastewater of this drain is biodegradable . In the present study, an attempt has been made to reduce the BOD load and COD levels of wastewater of Najafgarh drain using autochthonous microbial consortium . During this study the raw wastewater samples were treated for 6 h time interval with different concentration of consortium . It was observed that by increasing the existing microbial population in the wastewater sample by 150-200% there is a significant decrease in BOD and COD levels . Finally, BOD/COD ratios before and after biotreatment have been analyzed to assess the efficacy of the natural consortium.

Photochem Photobiol Sci, 2002 Sep, 1(9), 678 - 85
Effects of ultraviolet radiation and PAR on the content of usnic and divaricatic acids in two arctic-alpine lichens; Bjerke JW et al.; The fruticose lichen Flavocetraria nivalis and the crustose lichen Ophioparma ventosa, both common in light-exposed arctic-alpine environments, were exposed to ultraviolet radiation (UVR) in growth chambers for 30 days . Treatment with visible light (PAR) served as control . Both species accumulate the UV-absorbing phenolic compound usnic acid in the upper cortex . The latter species also synthesises several UV-absorbing medullary compounds, among them divaricatic acid . The effects of treatment with UVR on the synthesis of these two compounds were investigated by analysing the compounds quantitatively by RP-HPLC . UV-exposed thallus tips of F . nivalis contained higher concentrations of usnic acid than those not grown under UVR . Both treatments had a positive effect on the synthesis of usnic acid in O . ventosa . An additional experiment with O . ventosa was performed by first storing samples in a low-light habitat for 1 year to obtain near-zero levels of phenolics, and thereby exposing the samples to UVR and PAR for 90 days . A rapid resynthesis of usnic acid was observed for both treatments . The amounts of divaricatic acid were highly variable in all groups, and were not correlated with usnic acid concentrations or treatments . A comparison of O . ventosa from three different habitat types showed that the highest usnic acid amounts were found in the habitat with the highest levels of solar radiation . Results indicate that the induction of usnic acid production by UVR depends on the species studied, and on how well acclimatised the lichen samples are to solar radiation before they are exposed to supplementary UVR . In lichens with an already well-developed internal screening capacity, like the population of F . nivalis, enhanced UVR need not induce further accumulation of usnic acid, but removal of UVR may induce a biodegradation of usnic acid . Results also indicate that PAR is just as important as UVR for triggering the resynthesis of usnic acid in shade-adapted lichens . Divaricatic acid seems to be of low importance for the UV-screening properties of O . ventosa.

Chemosphere, 2003 Jan, 50(3), 321 - 31
Comparison of biodegradation of surfactants in soils and sludge-soil mixtures by use of 14C-labelled compounds and automated respirometry; Gejlsbjerg B et al.; The biodegradability of dodecyl benzene sulphonate (LAS), nonylphenol-di-ethoxylate (NP2EO) and tridecyl-tetra-ethoxylate (LAE) in soil was examined by use of 14C experiments at two concentrations (10 and 400 mg/kg) . Increasing the concentration of test chemical from 10 to 400 mg/kg resulted in a decrease in the relative maximum mineralization rate and an increase in the estimated lag times of a factor of approximately 3.5 . In sludge-amended soil, the highest expected environmental concentration (just after sludge application) will be around 10 mg/kg for linear alkylbenzene sulphonate (LAS), while the concentration of NP2EO and linear alcohol ethoxylates (LAE) will be much lower . However, when using a respirometric method it is necessary to use a higher concentration of test substance in order to detect biodegradation . In our experiment, amendment with anaerobically digested sludge resulted in a decrease in the mineralization of LAS, NP2EO and LAE for all soils . Respirometric experiments were carried out at 400 mg/kg and could be used for estimation of biodegradation potential of LAS, NP2EO and LAE in soil and sludge-amended soil . For LAS, the results obtained from the respirometric experiments were similar to the results obtained in the 14C experiments, whereas NP2EO and LAE showed a faster degradation in the respirometric experiments.

Chemosphere, 2003 Jan, 50(3), 303 - 9
Trichloroacetic acid in Norway spruce/soil-system . I . Biodegradation in soil; Matucha M et al.; Trichloroacetic acid (TCA) as a phytotoxic substance affects health status of coniferous trees . It is known as a secondary air pollutant (formed by photooxidation of tetrachloroethene and 1,1,1-trichloroethane) and as a product of chlorination of humic substances in soil . Its break-down in soil, however, influences considerably the TCA level, i.e . the extent of TCA uptake by spruce roots . In connection with our investigations of TCA effects on Norway spruce, microbial processes in soil were studied using 14C-labeling . It was shown that TCA degradation in soil is a fast process depending on TCA concentration, soil properties, humidity and temperature . As a result, the TCA level in soil is determined by a steady state between uptake from the atmosphere, formation in soil, leaching and degradation . The process of TCA degradation in soil thus participates significantly in the chlorine cycle in forest ecosystems.

Chemosphere, 2003 Jan, 50(1), 29 - 38
Application of the headspace CO2 method (ISO 14 593) to the assessment of the ultimate biodegradability of surfactants: results of a calibration exercise; Painter HA et al.; In the recent review of the control of marketing surfactants used in detergents, the EU decided to increase the severity of the testing procedure by using the criterion of ultimate biodegradability (mineralization) rather than primary biodegradation (removal of the parent molecule) to ensure that possible harmful organic metabolites do not reach the environment . The relatively new ISO headspace CO2 test, considered to be an improvement on the OECD 301B (Sturm CO2) test was chosen . The method was subjected to a ring test by 11 laboratories using one of each of four classes of surfactants plus a poorly degradable reference surfactant; all laboratories satisfactorily applied the method . The necessary addition of silica gel to the medium containing the cationic surfactant, known as a class to be more inhibitory than other classes, was confirmed as a technique for avoiding inhibition of the inoculum . The biodegradability of the surfactants was in general agreement with results reported in the literature and the often reported variable values of % inorganic carbon (IC) produced of the theoretical was found . The anionic and cationic surfactants were readily biodegradable (%IC > 60), the non-ionic surfactant was well below the pass value, while the amphoteric was borderline . The IC production by the blank controls, one of the validity criteria, was about 0.3 mg C/100 ml test medium, equivalent to 3 mg C/l, as recommended in the ISO text . Mild conditions of pre-exposure of the inoculum to the test surfactant did not produce consistent worthwhile effects on either the percentage biodegradation or on its variability.

Bioresour Technol, 2003 Jan, 86(2), 171 - 5
Anaerobic degradation of No . 2 diesel fuel in the wetland sediments of Barataria-Terrebonne estuary under various electron acceptor conditions; Boopathy R; The biodegradation of No . 2 diesel fuel under anaerobic conditions was investigated using sediments collected from wetlands of Barataria-Terrebonne estuary in Louisiana . The results indicated enhanced biodegradation of diesel fuel under sulfate-reducing, nitrate-reducing, methanogenic, and mixed electron acceptor conditions . However, the rate of diesel degradation was the highest under mixed electron acceptor conditions followed in order by sulfate-reducing, methanogenic, and nitrate-reducing conditions . Under mixed electron acceptor condition, 99% removal of diesel fuel was achieved within 510 days, while under sulfate-reducing condition 62% degradation of diesel fuel was observed for the same period . Diesel fuel was also degraded to a smaller extent in the culture condition where electron acceptors were not supplemented (natural attenuation condition) . This study showed evidence for enhanced diesel fuel metabolism in a mixed microbial population system similar to any contaminated field site, where a heterogeneous microbial population exists.

Pest Manag Sci, 2003 Mar, 59(3), 259 - 68
Monitoring of atrazine treatment on soil bacterial, fungal and atrazine-degrading communities by quantitative competitive PCR; Martin-Laurent F et al.; We report the development of quantitative competitive (QC) PCR assays for quantifying the 16S, 18S ribosomal and atzC genes in nucleic acids directly extracted from soil . QC-PCR assays were standardised, calibrated and evaluated with an experimental study aiming to evaluate the impact of atrazine application on soil microflora . Comparison of QC-PCR 16S and 18S results with those of soil microbial biomass showed that, following atrazine application, the microbial biomass was not affected and that the amount of 16S rDNA gene representing 'bacteria' increased transitorily, while the amount of 18S rDNA gene representing fungi decreased in soil . In addition, comparison of atzC QC-PCR results with those of atrazine mineralisation revealed that, in response to atrazine treatment, the amount of atzC gene increased transitorily in soil pre-treated with atrazine, suggesting that accelerated atrazine biodegradation in soil could be due to a transient increase in the size of the atrazine mineralising community.

Environ Sci Pollut Res Int, 2002, Spec No 1, 34 - 8
Applied waste-free recovery of methanol: a sustainable solution for chromatography laboratories; Stepnowski P et al.; In this paper, we present appliedmethanol recycling technology utilising chromatographic applications, which has been designed for an academic-size institution . The procedure is combined out of proper recovery technique and the biodegradation method intended for postprocessing residues . Additionally, analytical methods controlling the quality of the process are described in detail in order to enable full transfer of the proposed methodology to the analogous institution . The recovered solvent is of relatively high purity (> 99.92%), containing traces of water and volatile compounds . The spectral purity is sufficient to employ recycled methanol in HPLC applications where low wavelength detection is necessary . Biodegradation of distillation first-cuts and still bottoms is implemented using isolated strains of Methylobacterium organophilum . During the biodegradation process, a series of carotenoids are biosynthesized, which are of a high commercial value . The proposed application, therefore, offers not only a sustainable, waste-free solution in handling methanol waste, but can also serve as a potential source of value.

Environ Sci Pollut Res Int, 2002, Spec No 1, 19 - 26
Biodegradation of dimethylphenols by bacteria with different ring-cleavage pathways of phenolic compounds; Viggor S et al.; The biodegradation of 3,4, 2,4, 2,3, 2,6 and 3,5-dimethylphenol in combination with phenol and p-cresol by axenic and mixed cultures of bacteria was investigated . The strains, which degrade phenol and p-cresol through different catabolic pathways, were isolated from river water continuously polluted with phenolic compounds of leachate of oil shale semicoke ash heaps . The proper research of degradation of 2,4 and 3,4-dimethylphenol in multinutrient environments was performed . The degradation of phenolic compounds from mixtures indicated a flux of substrates into different catabolic pathways . Catechol 2,3-dioxygenase activity was induced by dimethylphenols in Pseudomonas mendocina PC1, where meta cleavage pathway was functional during the degradation of p-cresol . In the case of strains PC18 and PC24 of P . fluorescens, the degradation of p-cresol occurred via the protocatechuate ortho pathway and the key enzyme of this pathway, p-cresol methylhydroxylase, was also induced by dimethylphenols . 2,4 and 3,4-dimethylphenols were converted into the dead-end products 4-hydroxy-3-methylbenzoic acid and 4-hydroxy-2-methylbenzoic acid . In the degradation of 3,4-dimethylphenol, the transient accumulation of 4-hydroxy-2-methylbenzaldehyde repressed the consumption of phenol from substrate mixtures . A mixed culture of strains with different catabolic types made it possible to overcome the incompatibilities at degradation of studied substrate mixtures.

Environ Sci Pollut Res Int, 2002, Spec No 1, 8 - 14
Analysis of river pollution data from low-flow period by means of multivariate techniques: a case study from the oil-shale industry region, northeastern Estonia; Truu J et al.; The oil-shale industry has created serious pollution problems in northeastern Estonia . Untreated, phenol-rich leachate from semi-coke mounds formed as a by-product of oil-shale processing is discharged into the Baltic Sea via channels and rivers . An exploratory analysis of water chemical and microbiological data sets from the low-flow period was carried out using different multivariate analysis techniques . Principal component analysis allowed us to distinguish different locations in the river system . The riverine microbial community response to water chemical parameters was assessed by co-inertia analysis . Water pH, COD and total nitrogen were negatively related to the number of biodegradative bacteria, while oxygen concentration promoted the abundance of these bacteria . The results demonstrate the utility of multivariate statistical techniques as tools for estimating the magnitude and extent of pollution based on river water chemical and microbiological parameters . An evaluation of river chemical and microbiological data suggests that the ambient natural attenuation mechanisms only partly eliminate pollutants from river water, and that a sufficient reduction of more recalcitrant compounds could be achieved through the reduction of wastewater discharge from the oil-shale chemical industry into the rivers.

Environ Sci Technol, 2003 Feb 15, 37(4), 691 - 700
Caffeine, an anthropogenic marker for wastewater comtamination of surface waters; Buerge II et al.; The suitability of caffeine as a chemical marker for surface water pollution by domestic wastewaters was assessed in this study . Caffeine concentrations in influents and effluents of Swiss wastewater treatment plants (WWTPs, 7-73 and 0.03-9.5 microg/L, respectively) indicated an efficient elimination of 81-99.9% . Corresponding loads in untreated wastewater showed small variations when normalized forthe population discharging to the WWTPs (15.8 +/- 3.8 mg person(-1) d(-1)), reflecting a rather constant consumption . WWTP effluent loads were considerably lower (0.06 +/- 0.03 mg person(-1) d(-1)), apart from installations with low sludge age (< or = 5 d, loads up to 4.4 mg person(-1) d(-1)) . Despite the efficient removal in most WWTPs, caffeine was ubiquitously found in Swiss lakes and rivers (6-250 ng/ L), except for remote mountain lakes (<2 ng/L; analytical procedure for wastewater and natural waters: SPE, GC-MS-SIM or GC-MS-MS-MRM, internal standard 13C3-labeled caffeine) . Caffeine concentrations in lakes correlated with the anthropogenic burden by domestic wastewaters, demonstrating the suitability of caffeine as a marker . A mass balance for Greifensee revealed that approximately 1-4% of the wastewaters had been discharged without treatment, presumably on rainy days when the capacity of WWTPs had been exceeded . For Zurichsee, it could be shown that the monthly inputs of caffeine correlated with precipitation data . The depth- and seasonal-dependent concentrations in this lake were adequately rationalized by a numerical model considering flushing, biodegradation, and indirect photodegradation via HO . radicals as elimination processes and caffeine inputs as fitting variables.

Environ Health Perspect, 2002 Dec, 110 Suppl 6, 943 - 6
The role of cell bioaugmentation and gene bioaugmentation in the remediation of co-contaminated soils; Pepper IL et al.; Soils co-contaminated with metals and organics present special problems for remediation . Metal contamination can delay or inhibit microbial degradation of organic pollutants such that for effective in situ biodegradation, bioaugmentation is necessary . We monitored the degradation of 2,4-dichlorophenoxyacetic acid (2,4-D) or 3-chlorobenzoate (3-CB) in two different soils with and without cadmium (Cd) contamination . Additionally, we evaluated the ability of bioaugmentation to enhance organic degradation in these co-contaminated soils . Finally, we determined whether enhanced degradation was due to survival of the introduced organism (cell bioaugmentation) or plasmid transfer to indigenous microbial populations (gene bioaugmentation) . In Brazito soil, dual inoculation with a Cd-resistant bacterium plus a known 2,4-D-degrading bacterium, Ralstonia eutropha JMP134, enhanced 2,4-D degradation . Escherichia coli D11, which lacks chromosomal genes necessary for complete 2,4-D mineralization, was used for gene bioaugmentation in Madera soil . Significant gene transfer of the plasmid to the indigenous populations was observed, and the rate of 2,4-D degradation was enhanced relative to that of controls . Cell bioaugmentation was further demonstrated when (Comamonas testosteroni was used to enhance biodegradation of 3-CB in Madera soil . In this case no transfer of plasmid pBRC60 to indigenous soil recipients was observed . For the Madera soil, nonbioaugmented samples ultimately showed complete 2,4-D degradation . In contrast, nonbioaugmented Brazito soils showed incomplete 2,4-D degradation . These studies are unique in showing that both cell bioaugmentation and gene bioaugmentation can be effective in enhancing organic degradation in co-contaminated soils . Ultimately, the bioaugmentation strategy may depend on the degree of contamination and the time frame available for remediation.

Biotechnol Appl Biochem, 2003 Apr, 37(Pt 2), 139 - 44
Phytoremediation of 2,4-dichlorophenol by Brassica napus hairy root cultures; Agostini E et al.; We have obtained hairy root cultures of Brassica napus with high biomass and genetic stability which produce peroxidases, enzymes involved in biodegradation processes . In this work, these hairy root cultures were used to study the removal of 2,4-dichlorophenol (2,4-DCP), a common contaminant in industrial effluents that is highly toxic for human and aquatic life . The optimum conditions to obtain high efficiency in the removal process were established . Roots were able to remove 2,4-DCP from aqueous solutions containing 100-1000 mg/l, in the presence of H(2)O(2) concentrations ranging from 5 to 10 mM . After a short period of incubation (15 min), high removal efficiencies were achieved (91-94%) and maximal removal, of approx . 97-98%, was obtained with 1 h of reaction . High removal efficiencies (93-95%) were observed in a broad pH range (pH 3-9), reaching 98-99% in the range pH 4-8 . Moreover, roots could be re-used, almost for six consecutive cycles, to remove 2,4-DCP . The oxidation catalysed by peroxidases would be the main mechanism involved in this process . The results suggest that these cultures could be useful tools for phytoremediation.

Biomaterials, 2003 May, 24(12), 2003 - 11
Enzyme induced biodegradation of polycarbonate-polyurethanes: dose dependence effect of cholesterol esterase; Tang YW et al.; The current study has investigated the influence of esterase activity (80-400units/ml) on the biodegradation of polycarbonate-urethanes (PCNUs) by cholesterol esterase (CE), with a particular interest in studying the influence of different hard segment structures and their contribution to sensitizing the polymer towards enzyme catalyzed hydrolysis . Polycarbonate based polyurethanes were synthesized with varying hard segment content as well as hard segment chemistry based on three different diisocyanates, 1,6-hexane diisocyanate (HDI), 4,4'-methylene bisphenyl diisocyanate (MDI) and 4,4-methylene biscyclohexyl diisocyanate (HMDI) . The effect of different chemistry on surface contact angle was measured in order to define the relative chemical nature of the surfaces . The enzyme dose response was found to be lower when hard segment content in the polymer was high . There was a very strong dependence on enzyme concentration for polyurethanes with different hard segment chemistry, despite the fact that the nature of the hydrolysable polycarbonate segment remained the same . The PCNU which showed the most dramatic dependence on enzyme concentration was synthesized with HMDI . At low enzyme concentration (80units/ml) this material was the most stable of the polymers while at elevated CE concentration (400units/ml) the polymer underwent a catastrophic breakdown . The findings suggested that protein binding on the surfaces was saturated even though enzyme degradation did not achieve saturation on any of the surfaces . The role of protein binding in modulating the hydrolytic action of the enzymes at different activity levels highlights a need for further study in this area.

Biomacromolecules, 2003 Mar-Apr, 4(2), 372 - 7
Lipase-catalyzed biodegradation of poly(epsilon-caprolactone) blended with various polylactide-based polymers; Li S et al.; Poly(epsilon-caprolactone) was blended with various polylactide-based polymers and processed to films by the solution casting method . Blends of 25/75, 50/50, 75/25, 90/10, and 95/5 (w/w) poly(epsilon-caprolactone)/poly(l-lactide), a 95/5 (w/w) blend of poly(epsilon-caprolactone) with a poly(d-lactide), a 50/50 (w/w) poly(l-lactide)-poly(d-lactide) mixture, and a poly(l-lactide-co-epsilon-caprolactone) copolymer were considered comparatively . The various phase-separated films were allowed to degrade in the presence of Pseudomonas lipase, biodegradation being monitored by proton nuclear magnetic resonance, size exclusion chromatography, differential scanning calorimetry, X-ray diffraction, and environmental scanning electron microscopy . The formation of separated phases during solvent evaporation and their morphologies are discussed . The introduction of poly(l-lactide) dramatically decreased the degradation rate of poly(epsilon-caprolactone)/poly(l-lactide) blends . The higher the percentage of poly(l-lactide), the slower the degradation, while the presence of cracks and increasing the lipase concentration acted in favor of the enzymatic degradation . Long-term enzymatic degradation of the various 95/5 blends was investigated over 480 h . The poly(epsilon-caprolactone) phase was enzymatically degraded by the lipase regardless of the blend type, the degradation rate depending on the nature of the co-components.

Biomacromolecules, 2003 Mar-Apr, 4(2), 321 - 9
Degradation of vulcanized and nonvulcanized polyisoprene rubbers by lipid peroxidation catalyzed by oxidative enzymes and transition metals; Sato S et al.; Despite numerous reports concerning the biodegradation of rubber materials, there has been no report of rubber degradation by fully characterized enzymes . In the present paper, we presented a new method to decompose nonvulcanized and vulcanized polyisoprene rubbers by controlling the free radical chain reactions of lipids using oxidative enzymes, manganese peroxidase (MnP), laccase (Lac), and horseradish peroxidase (HRP) . Nonvulcanized synthetic polyisoprene (IR) was degraded by the free radicals from unsaturated fatty acids produced by MnP, HRP, and a combination of Lac/1-hydroxybenzotriazole . In contrast, lipoxygenase caused no apparent degradation . Degradation of IR was also observed in lipid peroxidation initiated by the Fenton reaction (FR) and Mn(III), an oxidation product produced by MnP . Vulcanized polyisoprene rubber sheets were degraded by the lipid peroxidation initiated by HRP, MnP, Mn(III), and FR . Pyrolysis GC-MS analysis demonstrated that the lipid peroxidation liberated isoprenoid fragments from the vulcanized rubbers.

Int J Cardiovasc Intervent, 2003, 5(1), 13 - 6
Biodegradable stents as a platform to drug loading; Tsuji T et al.; Despite technical and mechanical improvement in coronary stents the incidence of restenosis caused by in-stent neointimal hyperplasia remains high . Oral administration of numerous pharmacological agents has failed to reduce restenosis after coronary stenting in humans, possibly owing to insufficient local drug concentration . Therefore, drug-eluting stents were developed as a vehicle for local drug administration . The authors developed a new drug-eluting polymer stent that is made of poly-l-lactic acid polymer mixed with tranilast, an anti-allergic drug that inhibits the migration and proliferation of vascular smooth muscle cells induced by platelet-derived growth factor and transforming growth factor->1 . Polymer stents might be superior to polymer-coated metallic stents as local drug delivery stents in terms of biodegradation and the amount of loaded drug . Drug-mixed polymer stents can be loaded with a larger amount of drug than can drug-coated metallic stents because the polymer stent struts can contain the drug . Clinical application is required to assess the safety and efficacy of drug-eluting polymer stents against stent restenosis.

Appl Environ Microbiol, 2003 Mar, 69(3), 1532 - 41
Synergistic degradation of linuron by a bacterial consortium and isolation of a single linuron-degrading variovorax strain; Dejonghe W et al.; The bacterial community composition of a linuron-degrading enrichment culture and the role of the individual strains in linuron degradation have been determined by a combination of methods, such as denaturing gradient gel electrophoresis of the total 16S rRNA gene pool, isolation and identification of strains, and biodegradation assays . Three strains, Variovorax sp . strain WDL1, Delftia acidovorans WDL34, and Pseudomonas sp . strain WDL5, were isolated directly from the linuron-degrading culture . In addition, subculture of this enrichment culture on potential intermediates in the degradation pathway of linuron (i.e., N,O-dimethylhydroxylamine and 3-chloroaniline) resulted in the isolation of, respectively, Hyphomicrobium sulfonivorans WDL6 and Comamonas testosteroni WDL7 . Of these five strains, only Variovorax sp . strain WDL1 was able to use linuron as the sole source of C, N, and energy . WDL1 first converted linuron to 3,4-dichloroaniline (3,4-DCA), which transiently accumulated in the medium but was subsequently degraded . To the best of our knowledge, this is the first report of a strain that degrades linuron further than the aromatic intermediates . Interestingly, the rate of linuron degradation by strain WDL1 was lower than that for the consortium, but was clearly increased when WDL1 was coinoculated with each of the other four strains . D . acidovorans WDL34 and C . testosteroni WDL7 were found to be responsible for degradation of the intermediate 3,4-DCA, and H . sulfonivorans WDL6 was the only strain able to degrade N,O-dimethylhydroxylamine . The role of Pseudomonas sp . strain WDL5 needs to be further elucidated . The degradation of linuron can thus be performed by a single isolate, Variovorax sp . strain WDL1, but is stimulated by a synergistic interaction with the other strains isolated from the same linuron-degrading culture.

Biosci Biotechnol Biochem, 2003 Jan, 67(1), 218 - 20
Biodegradation of bisphenol A by cultured cells of Caragana chamlagu; Chai W et al.; The biological degradation of 2,2-bis(4-hydroxyphenol)propane (1; bisphenol A, BPA), a representative endocrine disruptor, was studied with plant-cultured cells of Caragana chamlagu . An initial BPA concentration of 425 microM in an aqueous solution was degraded by C . chamlagu at 25 degrees C for 2 days in the dark, and two intermediates were then completely dissipated after 10 days.

J Bacteriol, 2003 Mar, 185(6), 2026 - 30
Identification and functional characterization of Sphingomonas macrogolitabida strain TFA genes involved in the first two steps of the tetralin catabolic pathway; Moreno-Ruiz E et al.; Five genes involved in the two initial steps of the tetralin biodegradation pathway of Sphingomonas macrogolitabida strain TFA have been characterized . ThnA1A2 and ThnA3A4, components of the ring-hydroxylating dioxygenase, were encoded in divergently transcribed operons . ThnA1, ThnA2, and ThnA3 were essential for tetralin ring-hydroxylating dioxygenase activity . ThnB was identified as a dehydrogenase required for tetralin biodegradation.

Chemosphere, 2003 May, 51(6), 529 - 37
Biodegradation of chemicals in a standardized test and in environmental conditions; Ahtiainen J et al.; The estimation of biodegradation rates is an important source of uncertainty in chemical risk assessment . The existing OECD tests for ready biodegradability have been developed to devise screening methods to determine whether a chemical is potentially easily biodegradable, rather than to predict the actual rate, of biodegradation in the environment . However, risk assessment needs degradation rates . In practice these rates are often estimated (default values) from ready biodegradability tests . These tests have many compromising arbitrary features compared to the situation in the real environment . One important difference is the concentration of the chemical . In wastewater treatment or in the environment many chemicals are present at ng l(-1) to microg l(-1) levels whereas in the tests the concentrations exceed 10-400 mg carbon per litre . These different concentrations of the chemical will lead to different growth kinetics and hence different biodegradation rates . At high concentrations the chemical, if it is degradable, can serve as a primary substrate and competent microorganisms will grow exponentially, resulting in a sigmoid biodegradation curve . At low environmental concentrations the chemical does not serve as a primary substrate, and therefore does not support significant growth of the degraders, and the substrate has a linear biodegradation rate . In this study the biodegradation rates of two reference chemicals, aniline and 4-chloroaniline, were compared in a standard method and in more realistic conditions at low concentrations, using 14C-labelled substances and different sources of inocula . Biomass evolution during the tests was monitored by adenosine triphosphate measurement and also on the basis of the residual 14C-activity in the particulate matter . The results partly support the thesis that low concentrations lead to different biodegradation kinetics compared to the concentrations used in the standard tests . Furthermore the biodegradation rates of the chemicals studied, particularly of 4-chloroaniline, in Finnish natural waters appeared to be lower than those reported in some other countries.

J Biomater Appl, 2003 Jan, 17(3), 183 - 96
Oral insulin--a perspective; Raj NK et al.; Diabetes mellitus is generally controlled quite well with the administration of oral medications or by the use of insulin injections . The current practice is the use of one or more doses, intermediate or long acting insulin per day . Oral insulin is a promising yet experimental method providing tight glycemic control for patients with diabetes . A biologically adhesive delivery systems offer important advantage over conventional drug delivery systems . The engineered polymer microspheres made of erodable polymer display strong adhesive interactions with gastrointestinal mucus and cellular lining can traverse both the mucosal epithelium and the follicle associated epithelium covering the lymphoid tissue of Peyer's patches . Alginate, a natural polymer recovered from seaweed is being developed as a nanoparticle for the delivery of insulin without being destroyed in the stomach . Alginate is in fact finding application in biotechnology industry as thickening agent, a gelling agent and a colloid stabilizer . Alginate has in addition, several other properties that have enabled it to be used as a matrix for entrapment and for the delivery of a variety of proteins such as insulin and cells . These properties include: a relatively inert aqueous environment within the matrix; a mild room temperature encapsulation process free of organic solvents; a high gel porosity which allows for high diffusion rates of macromolecules; the ability to control this porosity with simple coating procedures and dissolution and biodegradation of the system under normal physiological conditions.

J Chromatogr A, 2003 Feb 14, 987(1-2), 395 - 402
Process monitoring of anaerobic azo dye degradation by high-performance liquid chromatography-diode array detection continuously coupled to membrane filtration sampling modules; Plum A et al.; Process integrated microfiltration and ultrafiltration based membrane sampling modules were compared by means of HPLC with diode array detection based monitoring of an anaerobic azodye biodegradation process . The sampling matrix consisted of anaerobic sludge from a municipal wastewater treatment plant . The hydrolysed azo dye Reactive Black 5 (RB5-H) and three products (ionic and nonionic) released from reductive cleavage under anaerobic conditions were continuously monitored by simultaneously separation by ion-pair chromatography . Microfiltration membrane-based sampling showed no retention for any compound observed . Sampling by ultrafiltration significantly retained the observed ionic compounds between 58 and 83% whereas a nonionic compound was not retained . On-line monitoring of an oxygen-sensitive compound was possible whereas off-line detection failed . Robust long time monitoring could be performed for up to 1 week without cleaning the membrane.

Environ Int, 2003 Mar, 28(8), 687 - 90
An assessment of the toxicity of pyridinium chlorides and their biodegradation intermediates; Grabinska-Sota E et al.; Toxicity investigations were conducted for four pyridinium chlorides belonging to cationic surface-active substances (CSAS), which differed from each other in the numbers of methyl groups (CH(3)) in pyridinium ring.The crustacean Daphnia magna, the fish Lebistes reticulatus and the alga Scenedesmus quadricauda were chosen as biotests . Toxicity of examined preparations appeared to be very high but did not depend on their chemical structure . S . quadricauda was the most sensitive organism . Toxicity of intermediate products obtained in biological oxidation process was also examined . Biodegradation was conducted according to the "river water test" . It was found that only partial degradation took place while pyridinium chlorides constituted main energy and carbon source . Presence of biodegradation intermediate products was shown on the basis of 1H NMR analysis . Intermediates were not toxic to any biotests.

Hua Xi Kou Qiang Yi Xue Za Zhi, 2002 Jun, 20(3), 172 - 4, 183
{A fundamental study on bioreactions of Sr-HA}; Liao D et al.; OBJECTIVE: Sr-HA, a new type of hydroxyapatite biomaterial, was implanted into animals to study the bioreaction and character, which would be helpful for the further clinical applications in the future . METHODS: Totally 24 rabbits were divided into 3 groups . The bone defect of 6 mm x 12 mm x 4 mm was made at both mandibular angles of rabbits and Sr-HA of different proportion (10%, 5%, 0) was applied to reform the defects . One group of animals were killed randomly at 1, 3 and 6 months after operation to evaluate the material biological compatibility using anatomic, X-ray examination, histological and ECT methods . RESULTS: The histological photographs showed that Sr-HA caused little infection around implanted area and, almost was not repulsed by hosts . With the degradation of biomaterial, there was more apparent new bone growth in the area around Sr-HA than that around HA and some ossification can be found in soft tissue nearby . Also a tight osteointegrity was gradually got after the operation, according to the results of X-ray and, the border between Sr-HA and bone was hardly discovered at the 6th month after the operation . A more obvious nuclide assembling was observed at the side of Sr-HA by ECT images . With the biodegradation of Sr-HA, more new bone was intruded into the spare space of the biomaterial . CONCLUSION: Sr-HA has better biocompatibility and higher biodegradation than that of pure HA . It holds an excellent osteoinductivity and fair osteoconductivity to some degree too . So a more satisfying effect of bone defect rehabilitation was gained with the increasing new bone depositing in the free space of the material, when it degraded gradually.

Biosci Biotechnol Biochem, 2002 Dec, 66(12), 2755 - 8
Cloning, sequencing, and overexpression in Escherichia coli of a phenylserine dehydratase gene from Ralstonia pickettii PS22; Okuda H et al.; The structural gene coding for phenylserine dehydratase from Ralstonia pickettii PS22 was cloned into Escherichia coli cells, and the nucleotide sequence was identified . The predicted amino acid sequence had high sequence similarity to biodegradative and biosynthetic threonine dehydratases from E . coli and serine dehydratase from human liver . Transformed E . coli cells overproduced phenylserine dehydratase, and the recombinant enzyme was purified to homogeneity with a high yield and characterized.

Aquat Toxicol, 2003 Feb 26, 62(4), 305 - 19
In vivo metabolism and organ distribution of a branched 14C-nonylphenol isomer in pond snails, Lymnaea stagnalis L; Lalah JO et al.; The branched isomers of p-nonylphenol (NP) are perceived to be more resistant to biodegradation in aquatic environments as well as to have more estrogen-like toxicity than the straight chain isomers . By use of GC-MS, some of them have been identified and found to exist in higher concentrations in the isomeric compound mixture than the straight chain isomers . The investigations of the distribution and metabolism of these branched isomers in aquatic organisms are therefore considered to be important in understanding the mechanisms of toxicity of NP . A single tertiary isomer of NP, 4(3'-,6'-dimethyl-3'-heptyl)-phenol, was synthesized in the laboratory and used in in vivo studies of its organ distribution and metabolism in Lymnaea stagnalis L., following a constant exposure of the organisms to 14C-NP isomer in water over a period of 8 days at an average exposure concentration of 105 ppb (range: 93-116 ppb) . The results obtained clearly showed the distribution and bioconcentration of the isomer residues in various internal organs of Lymnaea after uptake in water and food . Analysis of the extracts of the organ tissues and faeces by HPLC and GC-MS after digestion with Pankreatin/beta-glucuronidase and nitric acid, respectively, showed that the isomer was metabolized by conjugation to glucuronic acid and hydroxylation to a catechol . The findings from these studies and their implications in the biotransformation and estrogenicity of NP in Lymnaea stagnalis L . are further discussed in detail in this paper.

J Control Release, 2003 Feb 14, 88(1), 55 - 64
Repairing of rabbit skull defect by dehydrothermally crosslinked collagen sponges incorporating transforming growth factor beta1; Ueda H et al.; Collagen sponges of various biodegradabilities were prepared by dehydrothermal crosslinking at 140 degrees C for different time periods . When the collagen sponges were radioiodinated and implanted subcutaneously into the back of mice, the radioactivity remaining at the implanted site decreased with time; the longer the time of dehydrothermal crosslinking, the slower the radioactivity decrement . The radioactivity following the subcutaneous implantation of collagen sponges incorporating (125)I-labeled transforming growth factor (TGF)-beta1 also decreased with time . The time profile of both the radioactivity remainings was in good accordance to each other, irrespective of the crosslinking time . This indicates that the TGF-beta1 incorporated in the sponges was released as a result of sponge biodegradation . Potential of collagen sponges incorporating 0.1 micro g of TGF-beta1 in repairing the defect of rabbit skulls was evaluated in a stress-unloaded state . Bone repairing was induced by application of the collagen sponges incorporating 0.1 micro g of TGF-beta1 whereas that of free TGF-beta1 at the same dose and TGF-beta1-free, empty collagen sponges were ineffective . The bone defect was histologically closed by the bone tissue newly formed 6 weeks after application . Bone mineral density (BMD) analysis revealed that the collagen sponge incorporating TGF-beta1 enhanced the BMD value at the bone defect to a significantly great extent compared with other agents . A maximum enhancement of BMD was observed for the collagen sponge incorporating TGF-beta1 which was prepared by dehydrothermal crosslinking for 6 h . It was concluded that the TGF-beta1 incorporated in the collagen sponge was released in a biologically active form as a result of sponge biodegradation, resulting in enhanced bone repairing at the skull defect . It is possible that for too slowly degraded sponges, the remaining physically impairs the bone repairing at the skull defect . Induction of bone repairing would not be achieved through a rapid release of TGF-beta1 from too fast-degraded sponge.

Lett Appl Microbiol, 2003, 36(3), 173 - 6
Biodegradation of the synthetic pyrethroid cypermethrin in used sheep dip; Grant RJ et al.; AIMS: To investigate the breakdown of cypermethrin synthetic pyrethroid (SP) insecticide-based used sheep dip (USD), with its indigenous microbial community and two previously isolated SP-degrading microorganisms . METHODS AND RESULTS: Cultures of USD (50 ml) containing 250 ml l(-1) cypermethrin were inoculated with the SP-degrading organisms and incubated at 25 degrees C with agitation at 80 rev min(-1) for 14 days . The viable cell counts and concentration of cypermethrin were monitored . A non-stimulated control was also carried out . The previously isolated bacteria were the most effective at degrading cypermethrin, leaving approximately two-thirds the concentration of SP as was found in the control . The non-stimulated cultures showed negligible breakdown of SP over the experimental period . CONCLUSIONS: The previously isolated SP-degrading bacteria could have a use in the treatment of SP USD . SIGNIFICANCE AND IMPACT OF STUDY: In situ treatment of SP-based USDs to detoxify the active ingredient before disposal could be very useful in helping to deal with agricultural pesticide waste . Such an approach, or by ex situ treatment would be more preferable to current methods, such as those of incineration and disposal to land.

Adv Space Res, 2003, 31(1), 249 - 53
Biodegradation pathway of an anionic surfactant (Igepon TC-42) during recycling waste water through plant hydroponics for advanced life support during long-duration space missions; Levine LH et al.; The degradation of an anionic surfactant (Igepon TC-42) was investigated as part of an integrated study of direct recycling of human hygiene water through hydroponic plant growth systems . Several chemical approaches were developed to characterize the degradation of Igepon and to measure the accumulation of intermediates such as fatty acids and methyl taurine . Igepon was rapidly degraded as indicated by the reduction of methylene blue active substances (MBAS) and component fatty acids . The Igepon degradation rate continued to increase over a period of several weeks following repeated daily exposure to 18 micrograms/l Igepon . The accumulation of free fatty acids and methyl taurine was also observed during decomposition of Igepon . The concentration of methyl taurine was below detection limit (0.2 nmol/ml) during the slow phase of Igepon degradation, and increased to 1-2 nmol/ml during the phase of rapid degradation . These findings support a degradation pathway involving initial hydrolysis of amide to release fatty acids and methyl taurine, and subsequent degradation of these intermediates . Published by Elsevier Science Ltd on behalf of COSPAR.

J Biomed Mater Res A, 2003 Mar 1, 64(3), 551 - 9
Controlled release of fibroblast growth factors and heparin from photocrosslinked chitosan hydrogels and subsequent effect on in vivo vascularization; Ishihara M et al.; Application of ultraviolet (UV) irradiation to a photocrosslinkable chitosan (Az-CH-LA) aqueous solution resulted within 10 s in an insoluble, flexible hydrogel . A low molecular weight acidic molecule like trypan blue and various high molecular weight molecules such as bovine serum albumin (BSA), heparin and protamine were all retained within the hydrogel, while a low molecular weight basic molecule like toluidine blue was rapidly released from the hydrogel . In the present work, we examined the retaining capability of the chitosan hydrogel for growth factors and controlled release of growth factors from the chitosan hydrogel in vitro and in vivo . Fibroblast growth factor-1 (FGF-1), fibroblast growth factor-2 (FGF-2), vascular endothelial growth factor(165) (VEGF(165)), heparin-binding epidermal growth factor (HB-EGF) in phosphate buffered saline (PBS) were mixed with Az-CH-LA aqueous solution to form growth factor-incorporated chitosan hydrogels . About 10-25% of the growth factor was released from a growth factor-incorporated chitosan hydrogel into PBS within the first day, after which no further substantial release took place . The growth factors interacted with Az-CH-LA molecules poly-ion complexation, and probably were unable to be released after the first day under the in vitro nondegradation conditions of the hydrogel . Although the FGF-1, FGF-2, and VEGF(165)-incorporated chitosan hydrogels on a culture plate significantly stimulated HUVEC growth, the stimulating activity of the growth factor-incorporated chitosan hydrogel was completely cancelled out by washing the hydrogel with PBS solution for 3 days or more . The stimulating activity on the HUVEC growth were however highly recovered by treating the washed growth factor-incorporated chitosan hydrogel during 7 days with chitinase and chitosanase to partly degrade the hydrogel, strongly suggesting that the growth factors within the hydrogel retained their biologically active forms . The chitosan hydrogel (100 microl) when implanted into the back of a mouse was biodegraded in about 10-14 days . When FGF-1- and FGF-2-incorporated chitosan hydrogels were subcutaneously implanted into the back of a mouse, significant neovascularization was induced near the implanted site of the FGF-1- and FGF-2-incorporated chitosan hydrogels . Furthermore, addition of heparin with either FGF-1 or FGF-2 into the hydrogel resulted in a significantly enhanced and prolonged vascularization effect . These results indicate that the controlled release of biologically active FGF-1 and FGF-2 with heparin is caused by biodegradation of the chitosan hydrogel, and subsequent induction of vascularization .

Water Sci Technol, 2003, 47(1), 291 - 6
The performance of a two-stage SBR system in treating dye containing wastewater; Won XH et al.; A two-stage SBR system treating the wastewater containing copper-phthalocyanin dye-Reactive Turquoise Blue KN-G (C . I . Reactive Blue 21, denoted by RTB) was investigated during a 200-cycle operation . The performance of the system, including pollutant removal rates, operating stability and sludge characteristics, may be a concern in the long-term run . The results shows that the system removed RTB efficiently despite the step-up RTB concentration from 13.1 to 107 mg/L in the influent . The average total removal rates of RTB were 81% to 92.5% due to the contribution of both anaerobic and aerobic stages, while stable effluent was produced with the help of the aerobic stage . The sludge in each reactor was in the steady state and of good activity on RTB removal . Moreover, the anaerobic sludge with the SVI value of 109.1 and the aerobic sludge with the SVI value of 103.2 had good settling properties, which was verified by hardly any presence of suspended solids in the effluent and an observation under an electron-scanning microscope . The adsorption and biodegradation were considered as the mechanism for the stability of the SBR system during the long-term run.

Water Sci Technol, 2003, 47(1), 113 - 20
Granular activated carbon (GAC) adsorption in tertiary wastewater treatment: experiments and models; Chaudhary DS et al.; Wastewater treatment has always been a major concern in the developed countries . Over the last few decades, activated carbon adsorption has gained importance as an alternative tertiary wastewater treatment and purification process . In this study, granular activated carbon (GAC) adsorption was evaluated in terms of total organic carbon (TOC) removal from low strength synthetic wastewater . This paper provides details on adsorption experiments conducted on synthetic wastewater to develop suitable adsorption isotherms . Although the inorganics used in the synthetic wastewater solution had an overall unfavourable effect on adsorption of organics, the GAC adsorption system was found to be effective in removing TOC from the wastewater . This study showed that equation of state (EOS) theory was able to fit the adsorption isotherm results more precisely than the most commonly used Freundlich isotherm . Biodegradation of the organics with time was the most crucial and important aspect of the system and it was taken into account in determining the isotherm parameters . Initial organic concentration of the wastewater was the determining factor of the model parameters, and hence the isotherm parameters were determined covering a wide range of initial organic concentrations of the wastewater . As such, the isotherm parameters derived using the EOS theory could predict the batch adsorption and fixed bed adsorption results of the multi-component system successfully . The isotherm parameters showed a significant effect on the determination of the mass transfer coefficients in batch and fixed bed systems.

Bioresour Technol, 2003 May, 88(1), 69 - 74
Kinetics of anaerobic biodegradation of resorcinol catechol and hydroquinone in upflow fixed film-fixed bed reactors; Latkar M et al.; Biodegradation of resorcinol, catechol and hydroquinone under anaerobic conditions was studied in identical upflow fixed film-fixed bed reactors . Kinetic constants; V(max) (maximum substrate utilization rate) and K(s) (Monod's half saturation constant) were determined for the three compounds using Lineweaver-Burk plot . V(max) for resorcinol was highest, followed by catechol and then by hydroquinone . When both resorcinol and catechol were fed to the resorcinol-acclimated reactor, resorcinol degradation was inhibited by catechol . The inhibition was of the uncompetitive type and V(max) for resorcinol was reduced by catechol.

Appl Environ Microbiol, 2003 Feb, 69(2), 909 - 16
Arthrobacter strain VAI-A utilizes acyl-homoserine lactone inactivation products and stimulates quorum signal biodegradation by Variovorax paradoxus; Flagan S et al.; Many Proteobacteria produce acyl-homoserine lactones (acyl-HSLs) and employ them as dedicated cell-to-cell signals in a process known as quorum sensing . Previously, Variovorax paradoxus VAI-C was shown to utilize diverse acyl-HSLs as sole sources of energy and nitrogen . We describe here the properties of a second isolate, Arthrobacter strain VAI-A, obtained from the same enrichment culture that yielded V . paradoxus VAI-C . Although strain VAI-A grew rapidly and exponentially on a number of substrates, it grew only slowly and aberrantly (i.e., linearly) in media amended with oxohexanoyl-HSL as the sole energy source . Increasing the culture pH markedly improved the growth rate in media containing this substrate but did not abolish the aberrant kinetics . The observed growth was remarkably similar to the known kinetics of the pH-influenced half-life of acyl-HSLs, which decay chemically to yield the corresponding acyl-homoserines . Strain VAI-A grew rapidly and exponentially when provided with an acyl-homoserine as the sole energy or nitrogen source . The isolate was also able to utilize HSL as a sole source of nitrogen but not as energy for growth . V . paradoxus, known to release HSL as a product of quorum signal degradation, was examined for the ability to support the growth of Arthrobacter strain VAI-A in defined cocultures . It did . Moreover, the acyl-HSL-dependent growth rate and yield of the coculture were dramatically superior to those of the monocultures . This suggested that the original coenrichment of these two organisms from the same soil sample was not coincidental and that consortia may play a role in quorum signal turnover and mineralization . The fact that Arthrobacter strain VAI-A utilizes the two known nitrogenous degradation products of acyl-HSLs, acyl-homoserine and HSL, begins to explain why none of the three compounds are known to accumulate in the environment.

J Biotechnol, 2003 Mar 6, 101(2), 119 - 30
Function and mechanism of a low-molecular-weight peptide produced by Gloeophyllum trabeum in biodegradation of cellulose; Wang W et al.; A special low-molecular-weight peptide named Gt factor, was isolated and purified via HPLC from the culture extract of the brown-rot fungus Gloeophyllum trabeum . It had high-affinity Fe(3+)-chelating ability and could reduce Fe(3+) to Fe(2+) . In the presence of O(2), it could produce hydroxyl radicals HO* . The effects of Gt factor on cellulose degradation suggested that Gt factor could disrupt inter- and intra- hydrogen bonds in cellulose chains by a HO*-involved mechanism . This resulted in depolymerization of cellulose chains, which produced more reducing and non-reducing ends, thus making cellulose accessible for further degradation . This pathway was quite different from the hydrolytic processes driven by cellulases, and Gt factor might play an important role in the early stage of cellulose depolymerization by brown-rot fungi .

J Agric Food Chem, 2003 Feb 12, 51(4), 947 - 56
Biodegradation of oak (Quercus alba) wood during growth of the shiitake mushroom (Lentinula edodes): a molecular approach; Vane CH et al.; The chemical transformations that occur during growth of the shiitake mushroom (Lentinula edodes) on oak (Quercus alba) were investigated to improve mushroom cultivation and utilization of the spent substrate . Oak logs were decayed by L . edodes over 8 years, during which time they were sampled at six intervals (30, 40, 66, 76, 77, and 101 months) . Fresh and decayed oak samples were analyzed using solid-state (13)C NMR and pyrolysis-gas chromatography-mass spectrometry as well as off-line thermochemolysis with tetramethylammonium hydroxide . Degraded oak exhibited lower carbon contents and increased oxygen content compared to the control . Solid-state (13)C NMR analysis revealed that polysaccharides were the major component of both fresh and decayed oak but that L . edodes mediated the preferential loss of cellulose and xylans as compared to lignin, which remained in an altered form . Several trends point toward the degradation of lignin, including a decrease in the proportion of syringyl units as compared to guaiacyl units and a reduction in side-chain length . An increase in guaiacyl and syringyl acid-to-aldehyde ratios occurred with growth, which suggested that the fungus had caused oxidation of Calpha-Cbeta bonds . The overall effect of L . edodes on oak is similar to that of many white-rot fungi, which simultaneously degrade all cell wall components.

Environ Sci Technol, 2003 Jan 15, 37(2), 321 - 7
Fate of nonylphenol ethoxylates and their metabolites in two Dutch estuaries: evidence of biodegradation in the field; Jonkers N et al.; The environmental behavior of nonylphenol ethoxylates (A9PEO) and their metabolites was investigated in field studies in the two Dutch estuaries Western Scheldt and the Rhine estuary . Using liquid chromatography-electrospray mass spectrometry (LC-ES-MS) analysis after solid-phase extraction, A9PEO, nonylphenol (NP), and the carboxylated metabolites (A9PEC) were determined in surface water and sediments . Maximum dissolved concentrations of 2.3, 0.9, and 8.1 microg L(-1), respectively, were found . In sediments, maximum concentrations of 242 and 1080 ng g(-1) for A9PEO and NP were observed . In almost half of the sediment samples, concentrations of A9PEC in sediments were below the detection limit . Occasionally relatively high values were observed, with a maximum of 239 ng g(-1) . Metabolites of the carboxy alkylphenoxy ethoxy acetic acids (CAPEC) type could not be detected in any of the sediment or water samples . In the Scheldt estuary, dissolved concentration profiles showed nonconservative behaviorfor all detected compound groups . While A9PEO and NP concentrations strongly decreased along the salinity gradient, this decrease was weaker for the A9PEC metabolites . The increasing concentration ratio of A9PEC/A9PEO clearly illustratesthe important role that aerobic biodegradation plays in the estuarine fate of these compounds . It is concluded that the oxidative hydrolytic degradation pathway is the main degradation route in this nonstratified estuary . At high salinities, where concentrations drop to background levels of around 50 ng L(-1), this ratio decreases to about unity . Simple model calculations show that this can be explained if continuous diffuse discharges (e.g . from the intensive shipping in the estuary) are assumed . For the stratified Rhine estuary the water concentration profiles are less pronounced, possibly due to more complicated and turbulent water flows and point sources from the Rotterdam harbors.

Biomaterials, 2003 Apr, 24(9), 1621 - 9
The properties of chitosan-gelatin membranes and scaffolds modified with hyaluronic acid by different methods; Mao JS et al.; The objective of the present study was to investigate the properties of chitosan-gelatin membranes or scaffolds, which were modified by incorporation of hyaluronic acid in the surface or bulk phase through co-crosslinking with N,N-(3-dimethylamino-propyl)-N'-ethyl carbodiimide (EDC) and N-hydroxysuccinimide (NHS) in 2-morpholinoethane sulfonic acid (MES) buffer . The comparative study on properties of surface modification (HA(S)) and polyblend membranes (HA(C)) revealed that gelatin was enriched on the surface of HA(C), while hyaluronic acid was enriched on the surface of the HA(S) . The HA(S) membranes made by surface modification method had a characteristic surface morphology . The corresponding scaffolds were prepared through freeze-drying . The incorporation of hyaluronic acid improved flexibility and fibroblasts adhesion, while slowing down the rate of biodegradation of chitosan-gelatin scaffold . Human fibroblasts adhered and proliferated well on the membranes or scaffolds in vitro.

Environ Toxicol Chem, 2003 Feb, 22(2), 272 - 5
Quantitative structure-biodegradation relationship study for biodegradation rates of substituted benzenes by river bacteria; Lu GH et al.; The biodegradation rate constant (K) of 21 substituted phenols, anilines, and benzoic acids was determined by using bacteria from the Songhua River (Jilin Province, China) as an inoculum . All of the compounds studied are readily biodegradable chemicals, as shown by their high K values . The quantitative structure-biodegradation relationship results showed that the biodegradation rate of the studied compounds is related mainly to the heat of formation (Hf) and the negative logarithm of the ionization constant (pKa), whereas no simple relationship exists with the n-octanol-water partition coefficients . The equation K = - 1.127 x 10(-3)Hf - 0.0388pKa + 0.859 was found to fit well (r2(adj) = 0.805), and the correlation coefficient between the predicted and the experimental K values was up to 0.908.

Wei Sheng Wu Xue Bao, 1999 Apr, 39(2), 127 - 31
{Comparison of lignocellulolytic enzyme profiles secreted by Panus conchatus and Phanerochaete chrysosporium during solid state cultures}; Wang C et al.; Most of white-rot fungi, such as Phanerochaete chrysosporium, can cause severe concomitant cellulose degradation during biodegradation of lignocellulose . Panus conchatus, a white-rot fungus, can cause efficient delignification of straw with only limited concomitant cellulose degradation . The results in comparison of lignocellulolytic enzyme profiles secreted by P . conchatus and P . chrysosporium during solid state cultures have shown that laccase and Mn-dependent peroxidase are main lignin-degrading enzymes of these two fungi respectively; high activities of xylanase are secreted by both fungi; and much lower activities of cellulases i.e . endo-glucanase, avicelase and cellobiase, especially endo-glucanase, are produced by P . conchatus during the whole cultures . The results further confirm that Panus conchatus has ability of strong selective delignification of lignocellulose.

Sheng Wu Yi Xue Gong Cheng Xue Za Zhi, 1998 Dec, 15(4), 323 - 4
{Preparation of chitosan-gelatin mixed film and study on it's biodegradability}; Lu F et al.; A chitosan-gelatin film is prepared and the biodegradability and biocompatibility of the film are investigated by animal experiments . Results suggest that chitosan-gelatin film may be biodegraded faster and it has good biocompatibility . Lysozyme may promote biodegradation of the mixed film.

Waste Manag Res, 2002 Dec, 20(6), 514 - 28
Modelling for environmental assessment of municipal solid waste landfills (part II: biodegradation); Garcia de Cortazar AL et al.; The biodegradation module of a simulation program for municipal solid waste landfills (MODUELO) was developed . The biodegradation module carries out the balance of organic material starting with the results of the hydrologic simulation and the waste composition . It simulates the biologic reactions of hydrolysis of solids and the gasification of the dissolved biodegradable material . The results of this module are: organic matter (COD, BOD and elemental components such as carbon, hydrogen, nitrogen, oxygen, sulfur and ash), ammonium nitrogen generated with the gas and transported by the leachates and the potential rates of methane and carbon dioxide generation . The model was calibrated by using the general tendency curves of the pollutants recorded in municipal solid waste landfills, fitting the first part of them to available landfill data . Although the results show some agreement, further work is being done to make MODUELO a useful tool for real landfill simulation.

J Environ Qual, 2003 Jan-Feb, 32(1), 40 - 6
Transport and biodegradation of perchlorate in soils; Tipton DK et al.; Perchlorate (ClO4-) contamination of ground water and surface water is a widespread problem, particularly in the western United States . This study examined the effect of biodegradation on perchlorate fate and transport in soils . Solute transport experiments were conducted on two surface soils . Pulses of solution containing perchlorate and Br- were applied to saturated soil columns at steady state water flow . Perchlorate behaved like a nonreactive tracer in Columbia loam (coarse-loamy, mixed, superactive, nonacid, thermic Oxyaquic Xerofluvent) but was degraded in Yolo loam (fine-silty, mixed, superactive, nonacid, thermic Mollic Xerofluvent) . Batch experiments demonstrated that perchlorate removal from solution in Yolo loam was caused by biodegradation . Other batch experiments with Yolo loam surface and subsurface soils, Columbia loam surface soil, and dredge tailings demonstrated that perchlorate biodegradation required anaerobic conditions, an adequate carbon source, and an active perchlorate-degrading microbial population . The sequential reduction of perchlorate and NO3- by an indigenous soil microbial community in Yolo loam batch systems was also studied . Nitrate reduction occurred much sooner than perchlorate reduction in soils that had not been previously exposed to perchlorate, but NO3- and perchlorate were simultaneously reduced in soils previously exposed to perchlorate . The results of this study have implications for in situ remediation schemes and for agricultural soils that have been contaminated by perchlorate-tainted irrigation water.

Wei Sheng Wu Xue Bao, 1998 Feb, 38(1), 63 - 9
{The biodegradation of trichloroethylene by a methanotrophic bacterium}; Shen R et al.; A Methylomonas (strain GYJ3) isolated in our laboratory was identified as the type II methanotroph on the basis of the intractytoplasmic membrane of the ultrastructure . The optimal culture conditions for production of the soluble from of methane monooxygenase (MMO) were determined, in which the ratio of methane to air in atmosphere was 2 to 1 and Cu2+ concentration was 1.5 mumol/L . The biodegradation of trichoroethylene(TCE) by the resting cells of the strain GYJ3 was studied . All experiments were performed with cells grown under above conditions and thus expressing soluble MMO . This results showed that TCE at the high concentration of 30 mg/L did not inhibit to the enzymes in the cells . Addition of formate increased the initial specific TCE degradation rates . The product of TCE oxidation was found to be toxic to the cells . The degree of inactivation of MMO was proportional to the amount of TCE degraded . The TCE degradation capacities(Tc) of resting cells was determined . In no-formate and formate-fed experiments, the TCE degradation capacities were found to be 0.0778 and 0.0851 mg of TCE/mg of dry cell, respectively.

Sheng Wu Yi Xue Gong Cheng Xue Za Zhi, 1998 Jun, 15(2), 183 - 5
{Biodegradation and biocompatibility of a chitosan film}; Lu F et al.; The biodegradability and biocompatibility of a chitosan film were investigated in mice . The results showed that chitosan films had a mild inflammatory reaction in the early days of grafting, and after 16 weeks the inflammation basically subsided . Chitosan films were easily biodegraded . Chitosan is a novel natural absorbable medical film material and has a good developmental prospect.

Hua Xi Yi Ke Da Xue Xue Bao, 2000 Sep, 31(3), 367 - 9
{Study on biodegradation of phenols in river water}; Zhao J et al.; This study on the biodegradation of phenols (phenol, o-methylphenol, o-chlorophenol and resorcinol) in river water was conducted by changing the main influential factors respectively . The results of experiment showed the phenols were greatly degradated in mild temperature, neutral pH and plenty of oxygen and the rank of the phenols biodegradation from great to small was resorcinol, phenol, o-methylphenol and o-chlorophenol . Presented in this paper is also a discussion on the biodegradation mechanism of phenols.

J Ind Microbiol Biotechnol, 2003 Jan, 30(1), 70 - 4 Epub 2003 Jan 03.
Degradation of polyvinyl alcohol by Sphingomonas sp . SA3 and its symbiote; Kim BC et al.; A total of 800 samples was taken from Taegu province, Korea, where many textile factories provide a source of polyvinyl alcohol (PVA) waste . These samples were screened for PVA-degrading bacteria . A new strain, SA3, was discovered which formed yellow colonies and used PVA as the sole carbon and energy source . Strain SA3 was identified as a Sphingomonas sp., based on the partial nucleotide sequence analysis of 16S ribosomal RNA, the presence of 2-hydroxymyristic acid (14:O 2-OH) and sphingolipids with d-17:0, d-18:0, d-19:1, and d-20:1 as the main dihydrosphingosines . This genus has not previously been reported as a PVA-degrading bacterium . Sphingomonas sp . SA3 needs a symbiote strain, SA2, for PVA degradation as a growth factor producer . In mixed cultures of these strains, the optimum temperature for PVA biodegradation ranged from 30 degrees C to 35 degrees C . The optimum pH was 8.0 and the most effective nitrogen source was NH(4)(+).

Hunan Yi Ke Da Xue Xue Bao, 2001 Jun 28, 26(3), 223 - 6
{Experimental study of pBMP/MPTCP in bone defects therapy}; Yi WH et al.; To develop a new substitute of bone graft, which is composed of porcine bone morphogenetic protein (pBMP) and the magnetic porous tricalcium phosphate (MPTCP), we investigated the effects of pBMP/MPTCP (Group A), autologous red bone marrow/porus tricalcium phosphate (BM/PTCP) (Group B), pBMP/PTCP(Group C) on the repair of bone defects created surgically in rabbits . By gross inspection, roentgenography examination, histological examination, immunohistochemistry test of osteocalcim, quantitive histological measurement of new bone formation and biomechanical test, three kinds of substitutes were proved to be biocompatible . Group A induced more new bone formation than other two groups, and showed a better biomechanical function(P < 0.01) . It is believed that pBMP/MPTCP has characteristics of strong osteoinductive capacity, good biocompatibility, excellent filling of bone defects and gradual biodegradation.

Appl Microbiol Biotechnol, 2003 Jan, 60(5), 594 - 600 Epub 2002 Dec 14.
Functional and structural analyses of trichloroethylene-degrading bacterial communities under different phenol-feeding conditions: laboratory experiments; Futamata H et al.; The effects of different phenol-feeding conditions on trichloroethylene (TCE) biodegradation and bacterial population structure in an aquifer soil community were studied . The soil sample, minerals, phenol, and TCE were mixed in glass bottles, which were then incubated under three different phenol-feeding conditions . First, phenol was supplied only once at 0.2 mM (condition 0.2P); second, it was added at 2.0 mM (condition 2.0P); and third, it was periodically supplied ten times at 0.2 mM (condition 0.2PS) . TCE concentrations remained stable under conditions 0.2P and 2.0P . In contrast, TCE was completely degraded under condition 0.2PS . TCE/phenol-degrading bacteria were enumerated indirectly and functionally by quantitative PCR . The low- K(s) (half saturation constant) group of phenol-degrading bacteria, exhibiting high TCE-degrading activity, yielded a 50-fold higher population under condition 0.2PS than under condition 2.0P . The bacterial community structure under condition 0.2PS was studied by denaturing gradient gel electrophoresis targeting the genes encoding 16S rRNA and the largest subunit of multicomponent phenol hydroxylase . Sequence analysis of the major bands detected indicated the predominance of the low- K(s) group of TCE/phenol-degrading bacteria belonging to beta-Proteobacteria . These results suggest that continuous supplementation with phenol at a low concentration increases the population of the low- K(s) group of TCE/phenol-degrading bacteria.

Chemosphere, 2003 Mar, 50(8), 1069 - 74
Biodegradation of 2,4-dichlorophenol in sequencing batch reactors augmented with immobilized mixed culture; Quan X et al.; 2,4-Dichlorophenol (2,4-DCP) degrading mixed culture was immobilized in polyvinyl alcohol jel beads and supplemented to sequencing batch reactors (SBR) to treat 2,4-DCP containing wastewater . Impacts of bioaugmentation level on the performance of bioaugmented systems were studied . Results show that inoculum size affected the start-up time of the SBR systems . For the non-augmented SBR system, nine days was needed for the system to start-up, whereas it only took six, four, three and two days for the SBRs with 1.9%, 3.7%, 5.6% and 9.3% immobilized culture, respectively . In addition, bioaugmented SBR systems demonstrated stronger capacity to cope with high 2,4-DCP shock loading than the control system . The control SBR failed to treat 2,4-DCP at 166 mg/l in influent, while the SBR with 1.9% inoculation could successfully cope with 2,4-DCP at 166 mg/l, but failed at 250 mg/l, and the SBR with 3.7%, 5.6% and 9.3% immobilized culture could successfully degrade 250 mg/l 2,4-DCP in feed . Furthermore, the contributions to the removal of 2,4-DCP by the introduced and indigenous culture in an augmented SBR system at various operation stages were investigated . It was found that augmented culture played the primary role in degrading 2,4-DCP at the beginning of system start-up, but after one-month operation, both the indigenous and the introduced culture posed strong ability to degrade 2,4-DCP .

Environ Pollut, 2003, 122(2), 195 - 203
The dissipation, distribution and fate of a branched 14C-nonylphenol isomer in lake water/sediment systems; Lalah JO et al.; A single tertiary isomer which is believed to be one of the major branched isomers of the isomeric nonylphenol was synthesized for use in investigations on its metabolism and estrogenicity in aquatic organisms . The physico-chemical properties of the isomer were determined to enable the prediction of its behaviour in aquatic environments . From laboratory investigations on its dissipation and distribution in lake water, which are reported in this paper, it was found that it had a half-life of dissipation of 38.1 days and 20.1 days in an open lake water and in an open lake water/ sediment system, respectively, and to be rapidly partitioned in to sediment giving a high concentration factor of 1.76 after 28 days with an initial dose concentration of 2.52 ppm . The main dissipation route was found to occur through volatilization and co-distillation . The isomer was, however, found to be resistant to biodegradation in both the lake water and sediment, showing only a slight 9% loss (after 56 days) and 4.2% loss (after 28 days), of the 14C-residues in lake water and lake water/sediment systems, respectively, by microbial activity . Transformation to other more polar metabolites possibly by hydroxylation was also found to be minimal in both lake water and sediment samples after 14 days by HPLC analysis . After 7 days, only 2.25 and 7.4% transformation to a more polar metabolite was detected in lake water and sediment samples, respectively.

J Control Release, 2003 Jan 17, 86(2-3), 223 - 34
Poly(ethylene oxide)-modified poly(beta-amino ester) nanoparticles as a pH-sensitive biodegradable system for paclitaxel delivery; Potineni A et al.; The main objective of this study was to develop and characterize a pH-sensitive biodegradable polymeric nanoparticulate system for tumor-selective paclitaxel delivery . A representative hydrophobic poly(beta-amino ester) (poly-1) was synthesized by conjugate addition of 4,4'-trimethyldipiperidine with 1,4-butanediol diacrylate . Poly-1 (M(n) 10,000 daltons) nanoparticles were prepared by the controlled solvent displacement method in an ethanol-water system in the presence of Pluronic) F-108, a poly(ethylene oxide) (PEO)-containing non-ionic surfactant . Control and PEO-modified nanoparticles were characterized by Coulter counter, scanning electron microscopy (SEM), zeta potential measurements, and electron spectroscopy for chemical analysis (ESCA) . Polymer degradation studies were performed in phosphate-buffered saline (PBS, pH 7.4) at 37 degrees C . Paclitaxel loading capacities and efficiencies were determined and release studies were performed in Tween)-80 (0.1%, w/v)-containing PBS at 37 degrees C . Control and PEO-modified nanoparticles, labeled with rhodamine-123, were incubated with BT-20 cells to examine the uptake and cellular distribution as a function of time . PEO-modified nanoparticles with an average size of 100-150 nm and a positive surface charge of 37.0 mV were prepared . SEM analysis showed distinct smooth, spherical particles . The ether (-C-O-) peak of the C(1s) envelope in ESCA confirmed the surface presence of PEO chains . Polymer biodegradation studies showed that almost 85% of the starting material degraded after 6 days . The maximum paclitaxel loading efficiency attained was 97% at 1.0% (w/w) of the drug . Paclitaxel release studies showed that approximately 10% was released in the first 24 h, 80% after 3 days, and the entire content was released in approximately 5 days . After 1 h of incubation, a large fraction of the administered control and PEO-modified poly-1 nanoparticles was internalized in BT-20 cells . Results of this study demonstrate that PEO-modified poly-1 nanoparticles could provide increased therapeutic benefit by delivering the encapsulated drug to solid tumors.

Mar Pollut Bull, 2002 Nov, 44(11), 1236 - 42
Weathering of an Arctic oil spill over 20 years: the BIOS experiment revisited . Baffin Island Oil Spill; Prince RC et al.; A small experimental oil spill was conducted on the northern tip of Baffin Island Nunavut, Canada (72 degrees 31' N, 79 degrees 50' W) in August 1981, and the natural weathering of the oil has been followed by periodic visits . This paper reports on the chemical composition of oil collected in August 2001 . The vast majority of the initial oil has gone, but small patches remain . Some samples remain essentially unaltered despite their 20 years of exposure to the elements, while others show that biodegradation and photooxidation can play important roles in removing the majority of the components of the oil . Using 17alpha(H)21beta(H)hopane as a conserved marker within the oil, we show that the most biodegraded sample has lost more than 87% of the hydrocarbons initially present, while another has lost a substantial proportion of its initial chrysene and alkylated congeners . Potential explanations for the different weathering patterns seen in samples collected from this small site are briefly discussed.

Environ Sci Technol, 2002 Dec 1, 36(23), 5139 - 46
Use of compound-specific stable carbon isotope analyses to demonstrate anaerobic biodegradation of MTBE in groundwater at a gasoline release site; Kolhatkar R et al.; Currently it is unclear if natural attenuation is an appropriate remedial approach for groundwater impacted by methyl tertiary butyl ether (MTBE) . Site-characterization data at most gasoline release sites are adequate to evaluate attenuation in MTBE concentrations over time or distance . But, demonstrating natural biodegradation of MTBE requires laboratory microcosm studies, which could be expensive and time-consuming . Recently, compound-specific carbon isotope ratio analyses (13C/12C expressed in delta13C notation) have been used to demonstrate aerobic biodegradation of MTBE in laboratory incubations . This study explored the potential of this approach to distinguish MTBE biodegradation from other abiotic processes in an anaerobic groundwater plume that showed extensive decrease in MTBE concentrations . To our knowledge, this is the first study to use delta13C of MTBE data in groundwater and laboratory microcosms to demonstrate anaerobic biodegradation of MTBE . The delta13C of MTBE in monitoring wells increased by up to 31 per thousand (-25.5 per thousand to +5.5 per thousand) along with a 40-fold decrease in MTBE concentrations . Anaerobic incubations in laboratory microcosms indicated up to 20-fold reduction in MTBE concentrations with a corresponding increase in delta13C of MTBE of up to 33.4 per thousand (-28.7 per thousand to +4.7 per thousand) in live microcosms . Little enrichment was observed in autoclaved controls . These results demonstrate that anaerobic biodegradation was the dominant natural attenuation mechanism for MTBE at this site . The estimated isotopic enrichment factors (epsilon(field) = -8.10 per thousand and epsilon(lab) = -9.16 per thousand) were considerably larger than the range (-1.4 per thousand to -2.4 per thousand) previously reported for aerobic biodegradation of MTBE in laboratory incubations . These observations strongly suggest that delta13C of MTBE could be potentially useful as an "indicator" of in-situ MTBE biodegradation.

Environ Sci Technol, 2002 Dec 1, 36(23), 5106 - 16
Field demonstration of successful bioaugmentation to achieve dechlorination of tetrachloroethene to ethene; Major DW et al.; A laboratory microcosm study and a pilot scale field test were conducted to evaluate biostimulation and bioaugmentation to dechlorinate tetrachloroethene (PCE) to ethene at Kelly Air Force Base . The site groundwater contained about 1 mg/L of PCE and lower amounts of trichloroethene (TCE) and cis-1,2-dichloroethene (cDCE) . Laboratory microcosms inoculated with soil and groundwater from the site exhibited partial dechlorination of TCE to cDCE when amended with lactate or methanol . Following the addition of a dechlorinating enrichment culture, KB-1, the chlorinated ethenes in the microcosms were completely converted to ethene . The KB-1 culture is a natural dechlorinating microbial consortium that contains phylogenetic relatives of Dehalococcoides ethenogenes . The ability of KB-1 to stimulate biodegradation of chlorinated ethenes in situ was explored using a closed loop recirculation cell with a pore volume of approximately 64,000 L The pilot test area (PTA) groundwater was first amended with methanol and acetate to establish reducing conditions . Under these conditions, dechlorination of PCE to cDCE was observed . Thirteen liters of the KB-1 culture were then injected into the subsurface . Within 200 days, the concentrations of PCE, TCE, and cis-1,2-DCE within the PTA were all below 5 microg/L, and ethene production accounted for the observed mass loss . The maximum rates of dechlorination estimated from field date were rapid (half-lives of a few hours) . Throughout the pilot test period, groundwater samples were assayed for the presence of Dehalococcoides using both a Dehalococcoides-specific PCR assay and 16S rDNA sequence information . The sequences detected in the PTA after bioaugmentation were specific to the Dehalococcoides species in the KB-1 culture . These sequences were observed to progressively increase in abundance and spread downgradient within the PTA . These results confirm that organisms in the KB-1 culture populated the PTA aquifer and contributed to the stimulation of dechlorination beyond cDCE to ethene.

Biodegradation, 2002, 13(4), 285 - 95
Microbial activity in soils following steam treatment; Richardson RE et al.; Steam enhanced extraction (SEE) is an aquifer remediation technique that can be effective at removing the bulk of non-aqueous phase liquid (NAPL) contamination from the subsurface, particularly highly volatile contaminants . However, low volatility compounds such as polynuclear aromatic hydrocarbons (PAHs) are less efficiently removed by this process . This research evaluated the effects of steam injection on soil microbial activity, community structure, and the potential for biodegradation of contaminants following steam treatment . Three different soils were evaluated: a laboratory-prepared microbially-enriched soil, soil from a creosote contaminated field site, and soil from a chlorinated solvent and waste oil contaminated field site . Results from field-scale steaming are also presented . Microbial activity before and after steam treatment was evaluated using direct epifluorescent microscopy (DEM) using the respiratory activity dye 5-cyano-2,3, ditolyl tetrazolium chloride (CTC) in conjunction with the fluorochrome 5-(4,6-dichlorotriazinyl) aminofluorescein (DTAF) to yield a quantitative assessment of active and total microbial numbers . DEM results indicate that steamed soils that were analyzed while still hot exhibited microbial activity levels that were below detection . However, soil samples that were slowly cooled, more closely reflecting the conditions of applied SEE, exhibited microbial activity levels that were comparable to presteamed soils . Samples from a field-site where steam was applied continuously for 6 weeks also showed high levels of microbial activity following cooling . The metabolic capabilities of the steamed communities were investigated by measuring cell growth in enrichment cultures on various substrates . These studies provided evidence that organisms capable of biodegradation were among the mesophilic populations that survived steam treatment . Fluorescent in situ hybridization (FISH) analysis of the soils with domain-level rRNA probes suggest that both Archaea and Bacteria survived steam exposure.

Biodegradation, 2002, 13(4), 251 - 60
Application of a reverse transcription-PCR assay to monitor regulation of the catabolic nahAc gene during phenanthrene degradation; Marlowe EM et al.; Biodegradation of polycyclic aromatic hydrocarbons (PAH), such as phenanthrene, in environmental samples is often limited by low bioavailability which results from a combination of low aqueous solubility and/or high sorption . The purpose of this study was to investigate the influence of agents that increase PAH bioavailability on expression of the PAH catabolic gene nahAc . Phenanthrene was used as a model PAH and Pseudomonasputida PpG7, which contains the NAH7 plasmid that encodes the genes responsible for naphthalene and phenanthrene degradation, was used as a model degrader . PAH bioavailability was altered by the addition of two biosurfactants, rhamnolipid and hydroxypropyl-beta-cyclodextrin (HPCD) . Gene expression was determined by extraction of bacterial mRNA followed by RT-PCR amplification of two transcripts; nahAc, a naphthalene dioxygenase gene, and rpoD, a housekeeping gene . Results indicate that the lag period preceding nahAc gene induction decreased from 312 to 48 h in the presence of biosurfactants . Expression of the nahAc gene, as measured by RT-PCR, in the presence of surfactants was bimodal on a temporal basis, indicating that induction stopped briefly during biodegradation . Cessation of induction could have resulted from the up-regulation of alternate pathways or the accumulation of toxic intermediates . In contrast, expression of the rpoD gene was maintained throughout the duration of each experiment . This research demonstrates that the use of a gene expression assay to monitor the impact of substrate bioavailability on substrate utilization provides unique information concerning the biodegradation process that cannot be obtained from more traditional biodegradation assays such as cell growth or substrate disappearance . Gene expression assays also have the potential for use in assessing the impact of other environmental factors on biodegradation.

Biodegradation, 2002, 13(4), 239 - 50
Mathematical modeling of precipitation and dissolution reactions in microbiological systems; Rittmann BE et al.; We expand the biogeochemical model CCBATCH to include a precipitation/dissolution sub-model that contains kinetic and equilibrium options . This advancement extends CCBATCH's usefulness to situations in which microbial reactions cause or are affected by formation or dissolution of a solid phase . The kinetic option employs a rate expression that explicitly includes the intrinsic kinetics for reaction or mass-transport control, the difference from thermodynamic equilibrium, and the aqueous concentration of the rate-limiting metal or ligand . The equilibrium feature can be used alone, and it also serves as check that the kinetic rate never is too fast and "overshoots" equilibrium . The features of the expanded CCBATCH are illustrated by an example in which the precipitation of Fe(OH)3(s) allows the biodegradation of citric acid, even though complexes are strong and not bioavailable . Precipitation releases citrate ligand, and biodegradation of the citrate increases the pH.

Nucleic Acids Res, 2003 Jan 1, 31(1), 262 - 5
The University of Minnesota Biocatalysis/Biodegradation Database: post-genomic data mining; Ellis LB et al.; The University of Minnesota Biocatalysis/Biodegradation Database (UM-BBD, provides curated information on microbial catabolism and related biotransformations, primarily for environmental pollutants . Currently, it contains information on over 130 metabolic pathways, 800 reactions, 750 compounds and 500 enzymes . In the past two years, it has increased its breath to include more examples of microbial metabolism of metals and metalloids; and expanded the types of information it includes to contain microbial biotransformations of, and binding interactions with many chemical elements . It has also increased the ways in which this data can be accessed (mined) . Structure-based searching was added, for exact matches, similarity, or substructures . Analysis of UM-BBD reactions has lead to a prototype, guided, pathway prediction system . Guided prediction means that the user is shown all possible biotransformations at each step and guides the process to its conclusion . Mining the UM-BBD's data provides a unique view into how the microbial world recycles organic functional groups . UM-BBD users are encouraged to comment on all aspects of the database, including the information it contains and the tools by which it can be mined . The database and prediction system develop under the direction of the scientific community.

Appl Environ Microbiol, 2003 Jan, 69(1), 275 - 84
Degradation of polycyclic aromatic hydrocarbons at low temperature under aerobic and nitrate-reducing conditions in enrichment cultures from northern soils; Eriksson M et al.; The potential for biodegradation of polycyclic aromatic hydrocarbons (PAHs)at low temperature and under anaerobic conditions is not well understood, but such biodegradation would be very useful for remediation of polluted sites . Biodegradation of a mixture of 11 different PAHs with two to five aromatic rings, each at a concentration of 10 micro g/ml, was studied in enrichment cultures inoculated with samples of four northern soils . Under aerobic conditions, low temperature severely limited PAH biodegradation . After 90 days, aerobic cultures at 20 degrees C removed 52 to 88% of the PAHs . The most extensive PAH degradation under aerobic conditions at 7 degrees C,53% removal, occurred in a culture from creosote-contaminated soil . Low temperature did not substantially limit PAH biodegradation under nitrate-reducing conditions . Under nitrate-reducing conditions,naphthalene, 2-methylnaphthalene, fluorene, and phenanthrene were degraded . The most extensive PAH degradation under nitrate-reducing conditions at 7 degrees C, 39% removal, occurred in a culture from fuel-contaminated Arctic soil . In separate transfer cultures from the above Arctic soil, incubated anaerobically at 7 degrees C, removal of 2-methylnaphthalene and fluorene was stoichiometrically coupled to nitrate removal . Ribosomal intergenic spacer analysis suggested that enrichment resulted in a few predominant bacterial populations,including members of the genera Acidovorax,Bordetella, Pseudomonas, Sphingomonas, and Variovorax . Predominant populations from different soils often included phylotypes with nearly identical partial 16S rRNA gene sequences (i.e., same genus) but never included phylotypes with identical ribosomal intergenic spacers (i.e., different species or subspecies) . The composition of the enriched communities appeared to be more affected by presence of oxygen, than by temperature or source of the inoculum.

Appl Environ Microbiol, 2003 Jan, 69(1), 191 - 8
Carbon and hydrogen isotopic fractionation during anaerobic biodegradation of benzene; Mancini SA et al.; Compound-specific isotope analysis has the potential to distinguish physical from biological attenuation processes in the subsurface . In this study, carbon and hydrogen isotopic fractionation effects during biodegradation of benzene under anaerobic conditions with different terminal-electron-accepting processes are reported for the first time . Different enrichment factors (epsilon ) for carbon (range of -1.9 to -3.6 per thousand ) and hydrogen (range of -29 to -79 per thousand ) fractionation were observed during biodegradation of benzene under nitrate-reducing, sulfate-reducing, and methanogenic conditions . These differences are not related to differences in initial biomass or in rates of biodegradation . Carbon isotopic enrichment factors for anaerobic benzene biodegradation in this study are comparable to those previously published for aerobic benzene biodegradation . In contrast, hydrogen enrichment factors determined for anaerobic benzene biodegradation are significantly larger than those previously published for benzene biodegradation under aerobic conditions . A fundamental difference in the previously proposed initial step of aerobic versus proposed anaerobic biodegradation pathways may account for these differences in hydrogen isotopic fractionation . Potentially, C-H bond breakage in the initial step of the anaerobic benzene biodegradation pathway may account for the large fractionation observed compared to that in aerobic benzene biodegradation . Despite some differences in reported enrichment factors between cultures with different terminal-electron-accepting processes, carbon and hydrogen isotope analysis has the potential to provide direct evidence of anaerobic biodegradation of benzene in the field.

Appl Environ Microbiol, 2003 Jan, 69(1), 146 - 53
Novel approach to the improvement of biphenyl and polychlorinated biphenyl degradation activity: promoter implantation by homologous recombination; Ohtsubo Y et al.; To improve the capabilities of microorganisms relevant for biodegradation, we developed a new genetic approach and applied it to the bph operon (bphEGF{orf4}A1A2A3CD{orf1}A4R) of Pseudomonas sp . strain KKS102 to enhance its biphenyl- and polychlorinated biphenyl (PCB)-degrading activity . A native promoter of the bph operon, which was under control, was replaced through homologous recombination by a series of promoters that had constitutive activity . By testing a series of promoters with various strengths, we were able to obtain strains that have enhanced degradation activity for biphenyl and PCBs . This strategy removes the rate-limiting factor associated with transcription and has the potential to improve the degradation activity of a wide variety of microorganisms involved in biodegradation.

Bioresour Technol, 2003 May, 87(3), 299 - 303
Effect of propionate toxicity on methanogenesis of night soil at phychrophilic temperature; Dhaked RK et al.; The effect of propionate concentrations on biodegradation of human waste (night soil) was studied at 10 degrees C . Propionate was toxic for the biomethanation at all the pH tested (6.0, 7.0 and 8.0) . The maximum reduction in biogas production in presence of 200 mM propionate was observed at pH 7.0 followed by 8.0 . The methane content in biogas also followed a similar trend and at pH 7.0 an 11.5% decrease was observed . Propionate caused the reduction of methanogenic count by an approximately 2log value . Total volatile fatty acids increased with the increase in propionate concentration and particularly accumulation of propionate was observed . The results were also compared with the 30 degrees C fermentation.

J Contam Hydrol, 2003 Feb, 60(3-4), 287 - 305
Modelling biodegradation of hydrocarbons in aquifers: when is the use of the instantaneous reaction approximation justified?
Koussis AD, Pesmajoglou S, Syriopoulou D.
In-situ bio-remediation is a viable cleanup alternative for aquifers contaminated by hydrocarbons such as BTEX . Transport models of varying complexity and capabilities are used to quantify their degradation . A model that has gained wide acceptance in applications is BIOPLUME II, which assumes that oxygen-limited biodegradation takes place as an instantaneous reaction . In this work we have employed theoretical analysis, using non-dimensional variables, and numerical modelling to establish a quantitative criterion demarcating the range of validity of the instantaneous reaction approximation against biodegradation kinetics . Oxygen was the limiting species and sorption was ignored . This criterion relates <Da>(o), the Dahmkohler number at oxygen depletion, to O(o)*, the ratio of initial to input oxygen concentration, <Da>(o) > or = 0.7(O(o)*)(2) + 0.1O(o)* + 1.8 . The derived <Da>(o) reflects the intrinsic characteristics of the physical transport and of the biochemical reaction, including the effect of biomass density . Relative availability of oxygen and hydrocarbons exerts a small influence on results . Theory, verified and refined via numerical simulations, showed that significant deviations of instantaneous reactions from kinetics are to be expected in the space-time region s<L(d), t<T(d) ('near source' and 'initial period') . Under the assumptions considered, numerical simulations also verified the wide applicability of the computationally efficient, stoichiometry-based (algebraic) BIOPLUME concept . Kinetic modelling is required only in active (engineered) bio-remediation cases, with high velocities (e.g., near pumped wells), and for short distances from the source .

J Contam Hydrol, 2003 Feb, 60(3-4), 229 - 49
Laboratory evidence of MTBE biodegradation in Borden aquifer material; Schirmer M et al.; Mainly due to intrinsic biodegradation, monitored natural attenuation can be an effective and inexpensive remediation strategy at petroleum release sites . However, gasoline additives such as methyl tert-butyl ether (MTBE) can jeopardize this strategy because these compounds often degrade, if at all, at a slower rate than the collectively benzene, toluene, ethylbenzene and the xylene (BTEX) compounds . Investigation of whether a compound degrades under certain conditions, and at what rate, is therefore important to the assessment of the intrinsic remediation potential of aquifers . A natural gradient experiment with dissolved MTBE-containing gasoline in the shallow, aerobic sand aquifer at Canadian Forces Base (CFB) Borden (Ontario, Canada) from 1988 to 1996 suggested that biodegradation was the main cause of attenuation for MTBE within the aquifer . This laboratory study demonstrates biologically catalyzed MTBE degradation in Borden aquifer-like environments, and so supports the idea that attenuation due to biodegradation may have occurred in the natural gradient experiment . In an experiment with batch microcosms of aquifer material, three of the microcosms ultimately degraded MTBE to below detection, although this required more than 189 days (or >300 days in one case) . Failure to detect the daughter product tert-butyl alcohol (TBA) in the field and the batch experiments could be because TBA was more readily degradable than MTBE under Borden conditions .

Chemosphere, 2003 Feb, 50(7), 929 - 37
Biodegradation of linear alkylbenzene sulfonates in sulfate-leached soil mesocosms; Elsgaard L et al.; Aromatic sulfonates (R-SO(3)(-)) can be used as sulfur sources by sulfate-starved bacteria in laboratory cultures and the corresponding phenols are excreted from the cells . The present study was conducted to demonstrate whether such desulfonation reactions also occur in sulfate-leached agricultural soil, where desulfonation of organic sulfur compounds may have agronomic importance as a S source for plants . Xenobiotic linear alkylbenzene sulfonates (LAS) were added to nominal concentrations of 0, 10 and 100 mgkg(-1) dry weight in a sandy soil that was depleted in sulfate by leaching the soil with water (sulfate depletion, approximately 75%) . The soil was incubated at 20 degrees C in duplicate 3-dm(3) mesocosms for 8 weeks . Primary degradation of LAS was rapid with half-lives of 1-4 days . Sulfophenylcarboxylates were identified and quantified as intermediates, whereas linear alkylphenols (the expected primary desulfonation products) were not detected by high-pressure liquid chromatography coupled with both fluorescence and electrospray ionization-mass spectrometry . Thus, LAS was used by the bacteria as a source of energy and carbon, rather than as a source of sulfur . Measurements of soil pH, fluorescein diacetate (FDA) hydrolysis and arylsulfatase activity showed that stable microbial conditions prevailed in the soil mesocosms . FDA hydrolysis (a measure of total microbial activity) was transiently inhibited at the highest LAS concentrations . Arylsulfatase activity (i.e., hydrolysis of aromatic sulfate esters) was not significantly affected by the soil incubation, although arylsulfatases may be upregulated in sulfate-starved bacteria . However, an increased production of arylsulfatase may be difficult to detect due to the background of extracellular arylsulfatases stabilised in the soil . Therefore, the present data does not exclude a regulatory response to sulfate depletion by the soil microorganisms . However, the importance of desulfonation reactions in natural environments still needs to be demonstrated.

J Agric Food Chem, 2003 Jan 1, 51(1), 218 - 23
Enzymic release of reducing sugars from oat hulls by cellulase, as influenced by Aspergillus ferulic acid esterase and trichoderma xylanase; Yu P et al.; Hydroxycinnamic acids, mainly ferulic and p-coumaric acids, are believed to be inhibitory to ruminal biodegradability of complex cell wall materials such as oat hulls . Previous studies have shown that a novel enzyme, Aspergillus ferulic acid esterase, and Trichoderma xylanase act synergistically to break the ester linkage between ferulic acid and the attached sugar of feruloyl polysaccharides, releasing ferulic acid from oat hulls . In this paper, we examined the enzymic release of reducing sugars from oat hulls by the actions of individual enzymes (Aspergillus ferulic acid esterase at 13 mU, 6.4 U, and 4678.4 U/assay; cellulase at 20 levels, ranging from 7.8 mU to 2772.7 U/assay; Trichoderma xylanase at 20 levels, ranging from 7.8 mU to 4096 U/assay) and by the combined action of cellulase at six levels (62.5 mU, 2 U, 16 U, 128 U, 1024 U, and 2772.7 U/assay), Aspergillus ferulic acid esterase at 13 mU/assay, and Trichoderma xylanase at two levels (1 U and 256 U/assay) . The amount of total acid-extractable reducing sugars in the oat hulls used in this study was 793.8 +/- 8.0 microg/mg . The results show that after a 24-h incubation with Aspergillus ferulic acid esterase alone, no reducing sugars were observed to be released from oat hulls . With cellulase as the sole enzyme, as the concentration increased from 7.8 mU to 2772.7 U/assay, the release of reducing sugars increased (P < 0.01) from 0 to 39% of the total present, with the highest release at 512 U/assay . With Trichoderma xylanase alone, as the concentration increased from 7.8 mU to 4096 U/assay, the release of reducing sugars increased (P < 0.01) from 4.9 to 33%, with the highest release at 2048 U/assay . When incubated together with Trichoderma xylanase (1 U or 256 U/assay) and Aspergillus ferulic acid esterase (13 mU/assay), cellulase at all six levels (62.5 mU, 2 U, 16 U, 128 U, 1024 U and 2772.7 U/assay) significantly increased the release of reducing sugars (P < 0.01) from 8 to 69% . These results indicate that the synergistic interaction between Aspergillus ferulic acid esterase and Trichoderma xylanase on the release of ferulic acid from feruloyl polysaccharides of oat hulls makes the remainder of the polysaccharides open for further hydrolytic attack and facilitates the accessibility of the main chain of polysaccharides to cellulase . This action extends the cell wall hydrolysis, thus releasing a higher yield of reducing sugars . Such enzymic pretreatment of oat hulls may provide a unique advantage to rumen microorganisms for the biodegradation of the complex cell walls of byproduct feeds such as oat hulls.

J Gen Appl Microbiol, 1997 Apr, 43(2), 97 - 103
Biodegradation of the mixture of 2,4,6-trichlorophenol, 4-chlorophenol, and phenol by a defined mixed culture; Bae HS et al.; Two new strains, Pseudomonas sp . TCP114 degrading 2,4,6-trichlorophenol (TCP) and Arthrobacter sp . CPR706 degrading 4-chlorophenol (4-CP), were isolated through a selective enrichment procedure . Both strains could also degrade phenol . The degradability of one component by a pure culture was strongly affected by the presence of other compounds in the medium . For example, when all three components (TCP, 4-CP, and phenol) were present in the medium, a pure culture of CPR706 could not degrade any of the components present . This restriction on degradability could be overcome by employing a defined mixed culture of the two strains . The mixed culture could degrade all three components in the mixture through cooperative activity . It was also demonstrated that the mixed culture could be immobilized by using calcium alginate for the semi-continuous degradation of the three-component mixture . Immobilization not only accelerates the degradation rate, but also enables reuse of the cell mass several times without losing the cells' degrading capabilities.

J Hazard Mater, 2003 Jan 31, 96(2-3), 277 - 90
Optimisation of Fenton's reagent usage as a pre-treatment for fermentation brines; Rivas FJ et al.; Pre-treatment of fermentation brines from green olives has been carried out by the Fe(II)/Fe(III)/H(2)O(2) system . Reagent concentration exerted a positive influence on chemical oxygen demand (COD) removal . Hydrogen peroxide uptake showed values in the range 0.3-1.6mol of COD eliminated per mol of H(2)O(2) consumed depending on operating conditions . The optimum working pH was found to be in the interval 2.0-3.5 . Reaction temperature increased the COD degradation rate, although similar COD conversion values were obtained after 5h of treatment regardless of the value of this parameter . An analysis of the biodegradability of this type of effluent demonstrated the beneficial effect of the chemical pre-oxidation . According to the experimental results, it is suggested that there is an inhibitory effect of the wastewater due to its COD content and nature rather than attributable to the presence of high amounts of sodium chloride . Biodegradation efficiency increased as temperature was raised up to 30 degrees C . A further increase of this parameter up to 40 degrees C resulted in the death of the microorganisms.

J Environ Sci (China), 2002 Oct, 14(4), 524 - 9
Biodegradation of acetanilide herbicides acetochlor and butachlor in soil; Ye CM et al.; The biodegradation of two acetanilide herbicides, acetochlor and butachlor in soil after other environmental organic matter addition were measured during 35 days laboratory incubations . The herbicides were applied to soil alone, soil-SDBS (sodium dodecylbenzene sulfonate) mixtures and soil-HA (humic acid) mixtures . Herbicide biodegradation kinetics were compared in the different treatment . Biodegradation products of herbicides in soil alone samples were identified by GC/MS at the end of incubation . Addition of SDBS and HA to soil decreased acetochlor biodegradation, but increased butachlor biodegradation . The biodegradation half-life of acetochlor and butachlor in soil alone, soil-SDBS mixtures and soil-HA mixtures were 4.6 d, 6.1 d and 5.4 d and 5.3 d, 4.9 d and 5.3 d respectively . The biodegradation products were hydroxyacetochlor and 2-methyl-6-ethylaniline for acetochlor, and hydroxybutachlor and 2,6-diethylaniline for butachlor.

J Environ Sci (China), 2002 Oct, 14(4), 474 - 81
A two-stage anaerobic system for biodegrading wastewater containing terephthalic acid and high strength easily degradable pollutants; Li XM et al.; The high strength easily biodegradable pollutants (represented by CODE) are strong inhibitors of terephthalic acid (TA) anaerobic biodegradation . At the same time, TA can inhibit easily biodegradable pollutants removal under anaerobic conditions to a limited extent . This mutual inhibition could happen and cause a low removal efficiency of both TA and CODE, when the effluent from TA workshops containing TA and easily biodegradable pollutants are treated by a single anaerobic reactor system . Based upon the treatment kinetics analysis of both TA degradation and CODE removal, a two-stage up-flow anaerobic sludge blanket and up-flow fixed film reactor(UASB-UAFF) system for dealing with this kind of wastewater was developed and run successfully at laboratory scale . An UASB reactor with the methanogenic consortium as the first stage removes the easily biodegradable pollutants(CODE) . An UAFF reactor as the second stage is mainly in charge of TA degradation . At a CODE loading of 15.3 g/(L.d) and a TA loading of 1.4 g/(L.d), HRT 18.5 h, the CODE and TA removal rate of the system reached 89.2% and 71.6%, respectively.

Chemosphere, 2002 Dec, 49(10), 1257 - 65
Laboratory shake flask batch tests can predict field biodegradation of aniline in the Rhine; Torang L et al.; The aim of this study was to compare degradation rates of aniline in laboratory shake flask simulation tests with field rates in the river Rhine . The combined events of a low flow situation in the Rhine and residual aniline concentrations in the effluent from the BASF treatment plant in Ludwigshafen temporarily higher than normal, made it possible to monitor aniline at trace concentrations in the river water downstream the wastewater outlet by means of a sensitive GC headspace analytical method . Aniline was analyzed along a downstream gradient and the dilution along the gradient was calculated from measurements of conductivity, sulfate and a non-readily biodegradable substance, 1,4-dioxane . Compensating dilution, field first-order degradation rate constants downstream the discharge of BASF were estimated at 1.8 day(-1) for two different dates with water temperatures of 21.9 and 14.7 degrees C, respectively . This field rate estimate was compared with results from 38 laboratory shake flask batch tests with Rhine water which averaged 1.5 day(-1) at 15 degrees C and 2.0 day(-1) at 20 degrees C . These results indicate that laboratory shake flask batch tests with low concentrations of test substance can be good predictors of degradation rates in natural water bodies--at least as ascertained here for short duration tests with readily degradable compounds among which aniline is a commonly used reference.

Cad Saude Publica, 2002 Nov-Dec, 18(6), 1599 - 607
{A study of groundwater contamination with organic fuels and potential public health impact in Itaguaí, Rio de Janeiro State, Brazil}; Silva RL et al.; Increasing attention is current focused on urban groundwater contamination with gasoline hydrocarbon compounds in Brazil . The compounds benzene, toluene, ethylbenzene, and xylenes (BTEX) contained in fuels are highly toxic and can have severe public health consequences, besides posing the risk of intake from the water table by way of contamination . After two years of a steady gasoline storage tank leak, water samples from private household wells in the district of Brisa Mar, Itaguai, Rio de Janeiro State, were analyzed and the concentration of BTEX compounds was evaluated . Two out of ten water samples from the study area presented BTEX concentrations above the National Water Quality Standard (Brazilian Health Ministry Ruling No . 1469/2000), in which the maximum permissible benzene concentration is 5 micro g.L-1 . Four others wells were also contaminated with nitrate, responsible for the induction of methemoglobinemia . Natural attenuation (intrinsic biodegradation) mechanisms through electron acceptors was also investigated in this study.

J Gen Appl Microbiol, 2001 Aug, 47(4), 181 - 186
Strain improvement of Aspergillus niger for enhanced lipase production; Sandana Mala JG et al.; The enhancement of lipase production from Aspergillus niger was attempted by ultraviolet (UV) and nitrous acid mutagenesis, and the mutants were selected on media containing bile salts . Nitrous acid mutants exhibited increased efficiency for lipase production when compared with UV mutants in submerged fermentation . The hyperproducing UV and nitrous acid mutants were further subjected to a second step of mutagenesis to devise an economical and ecofriendly technique for lipase production by the effective use of hydrocarbons . One percent kerosene was found to be optimal for lipase production, and one of the mutant strains NAII exhibited 2.53 times more increased lipase activity than the parental strain did . This investigation indicates a possible role for the A . niger mutant strains in the biodegradation of oil-polluted environments for the development of ecofriendly technologies.

J Gen Appl Microbiol, 2000 Apr, 46(2), 79 - 84
Cometabolic biodegradation of methyl tert-butyl ether by a soil consortium: Effect of components present in gasoline; Garnier PM et al.; A soil consortium was tested for its ability to degrade reformulated gasoline, containing methyl tert-butyl ether (MTBE) . Reformulated gasoline was rapidly degraded to completion . However, MTBE tested alone was not degraded . A screening was carried out to identify compounds in gasoline that participate in cometabolism with MTBE . Aromatic compounds (benzene, toluene, xylenes) and compounds structurally similar to MTBE (tert-butanol, 2,2-dimethylbutane, 2,2,4-trimethylpentane) were unable to cometabolize MTBE . Cyclohexane was resistant to degradation . However, all n-alkanes tested for cometabolic activity (pentane, hexane, heptane) did enable the biodegradation of MTBE . Among the alkanes tested, pentane was the most efficient (200 &mgr;g/day) . Upon the depletion of pentane, the consortium stopped degrading MTBE . When the consortium was spiked with pentane, MTBE degradation continued . When the ratio of MTBE to pentane was increased, the amount of MTBE degraded by the consortium was higher . Finally, diethylether was tested for cometabolic degradation with MTBE . Both compounds were degraded, but the process differed from that observed with pentane.

J Control Release, 2002 Dec 13, 85(1-3), 1 - 15
Sustained-release injectables formed in situ and their potential use for veterinary products; Matschke C et al.; The controlled drug delivery of hydrophilic and lipophilic drug substances via the parenteral route has gained increasing importance in the development of pharmaceutical dosage forms . In particular, the animal health industry has generated strong interest in long-term drug delivery for both companion and farm animals during the past few years . At present sustained-release injectables formed in situ for s.c./i.m . administration have become an attractive alternative to common slow release technologies such as microspheres or standard implants . In this context, technologies based on PLA/PLGA, sucrose acetate isobutyrate (SAIB) and the amphipathic molecules Poloxamer, glycerol monooleate or PEG-PLA-PEG copolymers, are discussed . Release periods from hours to months can be obtained by choosing one of these drug delivery technologies . The release times are strongly dependent on the biodegradation of the polymers and the physico-chemical properties of the drug substance used . Furthermore, the use of different solvents for the matrix-forming agents and the individual loading capacity are critically assessed . Additionally acceptance of the excipients for parenteral use by the regulatory authorities is closely considered . Scientific articles as well as patent publications are reviewed to give a wide overview of the existing approaches and their future potential for animal health products.

Chem Commun (Camb), 2002 Dec 7, (23), 2884 - 5
Towards biodegradable polyolefins: strategy of anchoring minute quantities of monosaccharides and disaccharides onto functionalized polystyrene, and their effect on facilitating polymer biodegradation; Galgali P et al.; A hypothesis was developed, and successfully tested, to greatly increase the rates of biodegradation of polyolefins, by anchoring minute quantities of glucose, sucrose or lactose, onto functionalized polystyrene (polystyrene-co-maleic anhydride copolymer) and measuring their rates of biodegradation, which were found to be significantly improved.

Environ Pollut, 2003, 121(1), 147 - 51
Effect of soil aggregation on the biodegradation of phenanthrene aged in soil; Nam K et al.; A study was conducted to determine the possible role of soil aggregates in the sequestration of phenanthrene and thus in the declined biodegradation of the hydrocarbon . Phenanthrene aged in Lima loam (2-mm aggregates) showed declined biodegradation with time of aging to the test bacterium P5-2 capable of using sorbed phenanthrene . In contrast, the compound aged in a soil reconstructed with 68% clay-silt and 32% sand that had been separated from the Lima loam was readily mineralized . The percentages of each fraction used were the same as those of the original soil . Biodegradation of aged phenanthrene was not affected significantly by varying the ratios of each fraction in reconstructed mixtures . In experiments with Lima loam, its clay-silt fraction, and its sand fraction, mineralization extent was much lower in soil aggregates compared with the other samples while all had similar organic carbon content of ca . 1.51% . This suggests that aggregation may be another important determinant in the reduced biodegradation of aged phenanthrene.

J Environ Qual, 2002 Nov-Dec, 31(6), 1824 - 30
Biodegradation during contaminant transport in porous media: V . The influence of growth and cell elution on microbial distribution; Yolcubal I et al.; This study investigated the interaction between microbial growth and cell elution, and their influence on resultant microbial distribution between the aqueous and solid phases during solute transport in a sandy, low-organic-carbon-content porous medium . Miscible displacement experiments were conducted with salicylate as the model compound, and with different initial conditions (e.g., substrate concentrations and cell densities) to attain various degrees of microbial growth . For each experiment, salicylate and dissolved oxygen concentrations as well as cell densities were monitored in the column effluent . Cell densities were also measured in the porous medium at the beginning and end of each experiment . Total microbial growth was determined in two ways, one based on a cell mass balance for the system and the other based on total amount of salicylate degraded . For conditions yielding a considerable amount of microbial growth, the majority of the biomass was associated with the aqueous phase (68-90%) . Conversely, under minimal-growth conditions, most cells (approximately 60-70%) were attached to particle surfaces . Significant cell elution was observed for most conditions, the rate of which increased in the presence of the substrate . The results suggest that the increase in aqueous-phase cells observed for the experiments exhibiting the greatest growth is associated with the production of new cells, and that under appropriate conditions aqueous-phase biomass can contribute significantly to contaminant biodegradation.

J Environ Qual, 2002 Nov-Dec, 31(6), 1809 - 23
Transport and degradation of toluene and o-xylene in an unsaturated soil with dipping sedimentary layers; Sovik AK et al.; A lysimeter trench was established at the Gardermoen delta (50 km north of Oslo, Norway) to study the flow of water and transport and degradation of aromatic jet fuel components (toluene and o-xylene) in the undisturbed unsaturated zone . Site investigations with ground-penetrating radar revealed the presence of dipping sedimentary layers within the foreset unit . This study has shown that the foreset bed of the Gardermoen delta structure provided a preferential flow path for the transport of the solute plumes, but did not have dramatic effects on the degradation potential under the current conditions . The degradation potential for toluene and o-xylene in the unsaturated zone at Gardermoen was very high and almost all of the injected hydrocarbons were biodegraded before reaching the saturated zone . However, the horizontal displacement of the plume showed that knowledge about sedimentary structures in the unsaturated zone is important for a sufficient monitoring of contaminant transport and for remediation purposes . Carbon dioxide and O2 were measured in situ simultaneously with extraction of water samples, and indicated aerobic biodegradation of toluene and o-xylene . Overall, first-order degradation coefficients were calculated to be in the range of 0.19 to 0.21 d(-1) and 0.10 to 0.11 d(-1) for toluene and o-xylene, respectively.

Environ Technol, 2002 Oct, 23(10), 1197 - 201
A self-regulated fed-batch reactor . Part II--Results obtained with a ready biodegradable substrate and an acclimatized mixed culture; Sequeira AS et al.; Following the development of the self-regulated fed-batch reactor, a few experiments were carried out with performance demonstration purposes . Results indicate that biodegradation kinetic constants are quite easy and that a large range of possibilities for the reactor application can be envisaged.

Environ Toxicol Chem, 2002 Dec, 21(12), 2640 - 8
Degradation and persistence of metolachlor in soil: effects of concentration, soil moisture, soil depth, and sterilization; Rice PJ et al.; The present study evaluated the influence of soil depth, soil moisture, and concentration on the persistence and degradation of metolachlor in soil . Greater percentages of metolachlor persisted in subsurface soils than in surface soil regardless of the soil moisture or initial herbicide concentration . Larger quantities of bound residues and extractable degradation products were found in the surface soils as a result of the increased soil sorption and biodegradation of metolachlor associated with the surface soil, which had more organic matter . Saturated soil favored the dissipation of metolachlor and the formation of soil-bound residues . Significantly greater quantities of a dechlorinated metabolite were measured in the saturated surface soil compared to the unsaturated soil . Mineralization of metolachlor to CO2 and volatilization of metolachlor or metolachlor degradates was minimal in surface and subsurface soils at both soil moistures and herbicide concentrations . Increased metolachlor concentrations did not inhibit microbial activity; however, the greater rate of application did result in the reduced percentage of applied {14C}metolachlor that was bound to surface or subsurface soil . A significant reduction in the quantity of extractable metolachlor degradates and unextractable soil-bound residues in sterile soil revealed the significance of biodegradation to the dissipation of metolachlor in soil.

Environ Toxicol Chem, 2002 Dec, 21(12), 2623 - 30
Investigation of an onsite wastewater treatment system in sandy soil: modeling the fate of surfactants; McAvoy DC et al.; Field monitoring data for three common laundry detergent surfactants were used to test the applicability of a mathematical model that was developed as a screening-level tool for predicting the fate and transport of consumer product ingredients in septic systems . This model takes into account the simultaneous effects of sorption and biodegradation on the transport of chemicals through a septic system . Predicted groundwater concentrations of alcohol ethoxylate (AE) and alcohol ethoxy sulfate (AES) surfactants were in excellent agreement with measured values . This good agreement was to some extent due to the fact that the biodegradation rates of AE and AES do not vary significantly as a function of the degree of oxygenation of the soil . However, using laboratory-measured soil biodegradation rates for linear alkylbenzene sulfonate (LAS), the model underpredicted measured LAS concentrations in groundwater downgradient from the drainage field . This underprediction was due to the fact that the groundwater beneath the drainage field was anoxic during certain parts of the year and LAS is not degradable under this condition . Measured LAS concentrations were consistent with an assumed in situ soil biodegradation rate that was lower than the rate measured under fully oxygenated laboratory conditions . A limitation of the model is that only one soil biodegradation rate can be input for the saturated zone, even though biodegradation rates may vary seasonally or with distance from the drainage field . However, the model was appropriate and useful as a screening tool for the sorbable organic compounds studied . The applicability of the model to other classes of compounds should be assessed before broader application.

Environ Toxicol Chem, 2002 Dec, 21(12), 2617 - 22
Investigation of an onsite wastewater treatment system in sandy soil: sorption and biodegradation of linear alkylbenzene sulfonate; Doi J et al.; The objective of this work was to determine the sorptive and biodegradable characteristics of linear alkylbenzene sulfonate (LAS) in a soil below a Florida, USA, septic system drainfield . Three distinct soil samples were collected from the septic system drainfield study site . These soils were used in laboratory sorption and biodegradation studies . Different concentrations of LAS were added, in radiolabeled and unlabeled forms, to a series of test vessels that contained upgradient groundwater and the soils collected from the study site . The sorption test was designed to determine the partitioning of LAS between groundwater and soil in each sample . Results indicated that the sorption distribution coefficient (Kd) decreased from 4.02 to 0.43 L/kg and that the rate of ultimate biodegradation (first-order rate constant, k1) decreased from 2.17 to 0.08/d with increasing distance (0.7-1.2 m vertically below ground surface {BGS} and 0 to 6.1 m horizontally) from the drainfield . The three soils showed 49.8 to 83.4% LAS mineralization (percentage of theoretical CO2) over 45- or 59-d test periods . These results demonstrate that subsurface soils in this system have the potential to sorb and biodegrade LAS.

Environ Toxicol Chem, 2002 Dec, 21(12), 2606 - 16
Investigation of an onsite wastewater treatment system in sandy soil: site characterization and fate of anionic and nonionic surfactants; Nielsen AM et al.; This study reports on the fate of linear alkylbenzene sulfonate (LAS), alcohol ethoxylate (AE), and alcohol ether sulfate (AES) surfactants in a home septic system near Jacksonville (FL, USA) that has been used since 1976 . The drainfield at this site resides in fine sand (< 6% silt and clay) with an unsaturated zone that ranges from 0 to 1.3 m . During the wettest times of the year, it is likely that effluent from the septic system passes directly into the groundwater without exposure to an unsaturated zone of soil . Groundwater was collected during two sampling events, representing seasonal high and low groundwater table levels, and analyzed for the surfactants LAS, AES, and AE . During the wet season, the unsaturated zone was approximately 0.01 m beneath the drainfield . During the dry season, the unsaturated zone was about 0.4 m below the drainfield . Alcohol ethoxylate was not detected in any groundwater samples during either sampling . Alcohol ether sulfate was not found in the dry season sampling, but traces of AES had migrated downgradient about 4.7 m horizontally and 1.8 m vertically in the wet season . Linear alkylbenzene sulfonate was detected in some dry season samples and had moved downgradient some 11.7 m horizontally and 3.7 m vertically in the wet season . These observations demonstrate that these surfactants were removed to a great extent; otherwise, they would have traveled more than 260 m downgradient, which is the calculated distance that a conservative tracer like bromide would have moved downgradient over the life of the system . The most likely removal mechanisms for these surfactants were biodegradation and sorption . Therefore, this study indicates that LAS, AE, and AES are readily removed from groundwater in soils below septic system drainfields even in situations with minimal unsaturated soil zones.

Environ Toxicol Chem, 2002 Dec, 21(12), 2526 - 35
The potential for estradiol and ethinylestradiol to sorb to suspended and bed sediments in some English rivers; Holthaus KI et al.; The endocrine-disrupting impact of steroid estrogens on fish will be strongly influenced by their distribution between sediment and water . Laboratory studies were performed to investigate the potential for sorption of 17beta-estradiol (E2) and 17alpha-ethinylestradiol (EE2) to bed and suspended sediments taken from five British rivers . Sediment material was collected from the Rivers Aire and Calder (located in urban and industrialized areas in Yorkshire, UK), the River Thames (at a relatively rural site in Oxfordshire, UK), and from the estuaries of the Rivers Tees and Tyne . Using anaerobic conditions to inhibit biodegradation, it was found that 80 to 90% of binding to bed sediments was complete within 1 d, but that an equilibrium had not been reached after 2 d . Bed sediments gave distribution coefficients (Kd) ranging from 4 to 74 L/kg for E2 and from 8 to 121 L/kg for EE2 for samples taken over a range of seasons and locations . Sorption to suspended sediment gave Kd values ranging from 21 to 122 L/kg for E2 and 19 to 260 L/kg for EE2 . However, these Kd values suggest less than 1% removal of the steroid estrogens from the aqueous phase given the ambient suspended sediment concentration . In the bed sediments, higher Kd values were associated with smaller particle size and higher organic carbon content . In most cases, the Kd values obtained for EE2 were higher than those for E2 by a factor of up to three.

Vet Hum Toxicol, 2002 Dec, 44(6), 358 - 61
Microbial binding and biodegradation of mycotoxins; Styriak I et al.; This contribution provides an overview of literature data on the microbial binding and biodegradation of mycotoxins . These data and preliminary results from our own laboratory suggest that mycotoxin-bacterial binding or biodegradation is a realistic process and encourages the screening of bacterial strains and their biodegradation potential.

J Appl Microbiol, 1997 Mar, 82(3), 310 - 6
Kinetic studies of biodegradation of insoluble compounds by continuous determination of oxygen consumption; Bouchez M et al.; Continuous determination of oxygen consumption by electrolytic respirometry has been experimented as a means to study the biodegradation kinetics of scarcely soluble environmental pollutants . The substrates used were the polycyclic aromatic hydrocarbons (PAH), naphthalene, phenanthrene, anthracene, fluoranthene and pyrene . The definition of an appropriate mode of PAH supply, either as crystals or more generally as a solution in a water non-miscible solvent, was found essential for yielding reproducible biodegradation kinetics . In these conditions, for all compounds tested, oxygen determination was found suitable for quantitative evaluation of PAH biodegradation and formation of biomass and soluble metabolites . The study of biodegradation kinetics with this methodology showed that a first phase of exponential growth could be characterized in most cases, followed by a phase of limited growth . Possible mechanisms involved in insoluble substrate uptake are discussed . During exponential growth, the bacteria utilized (although not necessarily exclusively) the PAH solubilized in the aqueous medium.

J Agric Food Chem, 2002 Dec 4, 50(25), 7493 - 6
Biodegradation of ochratoxin A by fungi isolated from grapes; Abrunhosa L et al.; Ochratoxin A is a mycotoxin present in several food products for which levels should be reduced . Chemical, physical, and biological methods have been proposed for the detoxification of mycotoxins, biological methods being the more promising ones . In this report, filamentous fungi isolated from Portuguese grapes were assessed for ochratoxin A degradation capabilities . It was observed that 51 of the 76 tested strains, predominantly aspergillus species, were able to degrade more than 80% of ochratoxin A added to the culture medium and that the most potent species (more than 95% of initial amount) were the black aspergilli, A . clavatus, A . ochraceus, A . versicolor, and A . wentii . Other fungi frequently isolated from grapes, such as Alternaria, Botrytis, Cladosporium, and Penicillium, also showed significant degradation capabilities . It was observed that the compounds obtained from the degradation of ochratoxin A by black aspergilli and by A . ochraceus and A . wentii strains were different.

J Appl Microbiol, 1997 Feb, 82(2), 186 - 90
Anaerobic biodegradation of pentachlorophenol in a liquor obtained after extraction of contaminated chips and wood powder; Beaudet R et al.; Recovery of 97.5% of the pentachlorophenol (PCP) in contaminated wood powder was obtained after extraction with 0.1% KOH solution at 60 degrees C for 75 min . Extraction with NaOH and Na2CO3 was less effective than KOH . The neutralized extract was treated using a methanogenic consortium in an upflow anaerobic fixed-film reactor . The reactor was operated at 29 degrees C for over 600 d . The best performance of the reactor was observed when the PCP liquor was supplemented with glucose and formate . Complete dechlorination of PCP and phenol removal was obtained for a PCP loading rate of 13.3-18.0 mg l(-1) of reactor volume d(-1) with recirculation of the effluent and a hydraulic retention time (HRT) of 0.5-0.6 d.

Appl Environ Microbiol, 2002 Dec, 68(12), 6162 - 71
Phylogenetic and kinetic diversity of aerobic vinyl chloride-assimilating bacteria from contaminated sites; Coleman NV et al.; Aerobic bacteria that grow on vinyl chloride (VC) have been isolated previously, but their diversity and distribution are largely unknown . It is also unclear whether such bacteria contribute to the natural attenuation of VC at chlorinated-ethene-contaminated sites . We detected aerobic VC biodegradation in 23 of 37 microcosms and enrichments inoculated with samples from various sites . Twelve different bacteria (11 Mycobacterium strains and 1 Nocardioides strain) capable of growth on VC as the sole carbon source were isolated, and 5 representative strains were examined further . All the isolates grew on ethene in addition to VC and contained VC-inducible ethene monooxygenase activity . The Mycobacterium strains (JS60, JS61, JS616, and JS617) all had similar growth yields (5.4 to 6.6 g of protein/mol), maximum specific growth rates (0.17 to 0.23 day(-1)), and maximum specific substrate utilization rates (9 to 16 nmol/min/mg of protein) with VC . The Nocardioides strain (JS614) had a higher growth yield (10.3 g of protein/mol), growth rate (0.71 day(-1)), and substrate utilization rate (43 nmol/min/mg of protein) with VC but was much more sensitive to VC starvation . Half-velocity constant (K(s)) values for VC were between 0.5 and 3.2 micro M, while K(s) values for oxygen ranged from 0.03 to 0.3 mg/liter . Our results indicate that aerobic VC-degrading microorganisms (predominantly Mycobacterium strains) are widely distributed at sites contaminated with chlorinated solvents and are likely to be responsible for the natural attenuation of VC.

Appl Environ Microbiol, 2002 Dec, 68(12), 5860 - 9
Cork taint of wines: role of the filamentous fungi isolated from cork in the formation of 2,4,6-trichloroanisole by o methylation of 2,4,6-trichlorophenol; Alvarez-Rodriguez ML et al.; Cork taint is a musty or moldy off-odor in wine mainly caused by 2,4,6-trichloroanisole (2,4,6-TCA) . We examined the role of 14 fungal strains isolated from cork samples in the production of 2,4,6-TCA by O methylation of 2,4,6-trichlorophenol (2,4,6-TCP) . The fungal strains isolated belong to the genera Penicillium (four isolates); Trichoderma (two isolates); and Acremonium, Chrysonilia, Cladosporium, Fusarium, Mortierella, Mucor, Paecilomyces, and Verticillium (one isolate each) . Eleven of these strains could produce 2,4,6-TCA when they were grown directly on cork in the presence of 2,4,6-TCP . The highest levels of bioconversion were carried out by the Trichoderma and Fusarium strains . One strain of Trichoderma longibrachiatum could also efficiently produce 2,4,6-TCA in liquid medium . However, no detectable levels of 2,4,6-TCA production by this strain could be detected on cork when putative precursors other than 2,4,6-TCP, including several anisoles, dichlorophenols, trichlorophenols, or other highly chlorinated compounds, were tested . Time course expression studies with liquid cultures showed that the formation of 2,4,6-TCA was not affected by a high concentration of glucose (2% or 111 mM) or by ammonium salts at concentrations up to 60 mM . In T . longibrachiatum the O methylation of 2,4,6-TCP was catalyzed by a mycelium-associated S-adenosyl-L-methionine (SAM)-dependent methyltransferase that was strongly induced by 2,4,6-TCP . The reaction was inhibited by S-adenosyl-L-homocysteine, an inhibitor of SAM-dependent methylation, suggesting that SAM is the natural methyl donor . These findings increase our understanding of the mechanism underlying the origin of 2,4,6-TCA on cork, which is poorly understood despite its great economic importance for the wine industry, and they could also help us improve our knowledge about the biodegradation and detoxification processes associated with chlorinated phenols.

Biodegradation, 2002, 13(2), 131 - 40
Priming effect as determined by adding 14C-glucose to modified controlled composting test; Tuomela M et al.; The development of new biodegradable packaging materials, especially biodegradable plastics, has created a need for biodegradability testing . The European standard for controlled composting test was used in this study for assessing if the addition of a test material results in excess CO2 production in compost . This effect, designated as the priming effect, would give an erroneous result for biodegradation, which is based on CO2 formation from the test material . Glucose was selected as a test substrate because it is the degradation product of starch and cellulose, which are major compounds of many packaging materials . Both 14C-glucose and non-labelled glucose was applied to nine compost samples of variable stability and age from two weeks to 1.5 years . CO2 and 14CO2 evolution were measured during the incubation . Biodegradation of glucose in unstable composts (age <6 months) was negative and 14CO2 evolution was poor, although the respective composts without glucose produced relatively high amounts of CO2 . It was concluded that a negative priming effect was observed in unstable composts, in which glucose remained mostly non-degraded and apparently inhibited the mineralization of native organic matter in the compost . In stable composts (age > or = 6 months), biodegradation of glucose was high and approximately equal to 14C-glucose mineralization, i.e., the composts showed no priming effect . Young composts were unsuitable for controlled composting test due to lack of stability . It is important to ensure that the compost inoculum used for the test is sufficiently stable.

Antonie Van Leeuwenhoek, 2002 Aug, 81(1-4), 99 - 106
Effects of resource supplies on the structure and function of microbial communities; Smith VH; The supplies of nutrients, and their elemental stoichiometry, can have significant impacts upon the structure and function of microbial communities . This review focuses on the effects of nutrient supplies on the biodegradation of organic matter, and on the dynamics of host-pathogen interactions . Analyses of data from the literature suggest significant effects of nitrogen:phosphorus supply ratios on the microbial decomposition of organic matter, and it is argued that these stoichiometric effects may have important implications for the fate and fluxes of carbon in natural ecosystems . In addition, it is shown that the supplies of nitrogen and phosphorus to the host can strongly influence the outcome of infections in both terrestrial and aquatic plants, suggesting that resource availability and resource supply ratios potentially may have significant effects on the health of many plant communities.

Water Sci Technol, 2002, 46(9), 137 - 45
Study on self-purification capacity for organic pollutants in stagnant water; Saito M et al.; Polluted water is abandoned or stored untreated in many places . Especially, small water bodies such as ditches, ponds, wastewater tanks, etc . have not yet well been considered . The self-purification stabilizes the wastewater, but oxygen supply limits the biodegradation process . In the natural environment, approximately 3 g oxygen can be dissolved per m2 per day if the water is completely deprived from dissolved oxygen; this is the magnitude of self-purification capacity . To improve the quality of polluted water with higher oxygen demand than natural reaeration capacity, enhanced aeration is required . The laboratory experiment disclosed that water trickling onto the water surface or shallow stirring of water less than 10 mm in depth increased the mass transfer rate significantly . At the same time, the methods were found more efficient than bubbling aeration of large-scale treatment plant in terms of energy input against oxygen supply . Though it is an efficient method, elaborate application will be necessary since the mass transfer rate is not as high as bubbling aeration.

Pediatr Radiol, 2002 Dec, 32(12), 839 - 43 Epub 2002 Oct 10.
Biodegradation of tungsten embolisation coils used in children; Kampmann C et al.; BACKGROUND: It has been suggested that tungsten coils (TCs) may corrode 30 months after transcatheter embolisation (TCE) . The aim of this study was to follow up children after TCE of aorto-pulmonary collaterals (APCs) with TCs . MATERIALS AND METHODS: Successful TCE of 99 APCs was performed in children using 152 TCs . Chest radiographs were obtained on the day after the procedure, after 3-6 months and 9-12 months, and yearly thereafter . RESULTS: Mean follow-up was 39.3 months . After 9-12 months, radiographs revealed a decrease in radio-opacity and reduction of coil width in 29 (37.6%) of 77 APCs . After a mean of 25 months (range 13-51 months), there was loss of visibility in 44 (57.2%) of 77 TCs and a reduction in 29 (37.6%) of 77 . After a mean of 39.3 months, all TCs showed decrease or loss of radio-opacity . Exponential function predicts complete biodegradation of 95% of TCs within 10 years after TCE (r2= 0.923) . After a mean of 28.4 months, repeat catheterisation was performed in 24 APCs with TCs with decreased or lost radio-opacity . Recanalisation had occurred in 58.3% . CONCLUSIONS: Dissolution occurred in 57.2% of TCs within a mean of 25 months, and within 39.3 months all TCs showed decrease or loss of radio-opacity . Recanalisation of closed APCs occurred in 58.3%.

J Biotechnol, 2003 Feb 13, 100(3), 261 - 5
Monitoring of two-stage anaerobic biodegradation using a BOD biosensor; Liu J et al.; A previously developed biosensor for fast estimation of short-term biochemical oxygen demand (BOD(st)) was used for off-line monitoring of intermediate products from the initial step of an anaerobic process in laboratory scale . Good agreement was generally achieved between the results from the biosensor method and the conventional 5-day test except for samples with high content of organic polymers . During the period of agreement between the measurement principles, good correlation was achieved between the biogas production rate and the organic loading rate . The results from this study demonstrate that BOD(st) can be a successful monitoring parameter to achieve a better process control.

Rapid Commun Mass Spectrom, 2002, 16(23), 2179 - 83
Technical considerations for RNA-based stable isotope probing: an approach to associating microbial diversity with microbial community function; Manefield M et al.; An ongoing challenge within microbial ecology is the development of methodologies that attribute microbial community functions to microbial diversity . One approach, involving the incorporation of stable isotopes from labelled tracer compounds into biological signature molecules (biomarkers), may overcome this current limitation . To examine the potential of RNA as the biomarker in stable isotope probing we have generated a series of atom % (13)C-enriched RNA samples through exploitation of the anabolic abilities of a phenol-degrading environmental isolate . Isotope ratio mass spectrometry was used to determine the atom % (13)C of each RNA sample (ca . 1-100%) . The corresponding buoyant density (1.755-1.795 g mL(-1)) was determined by equilibrium density gradient centrifugation and agarose gel electrophoresis . This empirically defined relationship between the atom % (13)C of RNA and its buoyant density suggests ribonucleic acids with atom % (13)C enrichments greater than 10% can be isolated by equilibrium density centrifugation . The processing and analysis of isolated RNA by reverse transcription polymerase chain reaction, denaturing gradient gel electrophoresis, cloning and sequencing are discussed . The RNA-based stable isotope probing protocol presented here will find particular utility in assessing the roles of microbial community members in the biodegradation of natural and anthropogenic xenobiotic compounds .

Appl Microbiol Biotechnol, 2002 Nov, 60(3), 361 - 6 Epub 2002 Sep 26.
Kinetics of biodegradation of mixtures of polycyclic aromatic hydrocarbons; Lotfabad SK et al.; The kinetics of biodegradation of polycyclic aromatic hydrocarbons (PAHs) by a mixed culture were determined in a creosote-contaminated soil and in a pristine soil . A competitive-inhibition model was able to represent the kinetics of degradation of PAHs from the creosote-contaminated soil, from the lag phase through to active degradation, but not data from pristine soil with the same PAHs alone and in mixtures . The presence of phenanthrene introduced a lag phase of 4.5 days in the degradation of fluoranthene and 5 days for chrysene . Rapid degradation of pyrene followed a lag phase of circa 5 days, regardless of the presence of other PAHs . These results show that even when kinetics of PAH degradation by mixed cultures appear to follow competitive-inhibition kinetics, the underlying mechanisms may be more complex.

Int J Pharm, 2002 Dec 5, 249(1-2), 127 - 38
Biodegradable poly(epsilon -caprolactone) nanoparticles for tumor-targeted delivery of tamoxifen; Chawla JS et al.; To increase the local concentration of tamoxifen in estrogen receptor (ER) positive breast cancer, we have developed and characterized nanoparticle formulation using poly(epsilon -caprolactone) (PCL) . The nanoparticles were prepared by solvent displacement method using acetone-water system . Particle size analysis, scanning electron microscopy, zeta potential measurements, and differential scanning calorimetry (DSC) were used for nanoparticle characterization . Biodegradation studies were performed in the presence and absence of Pseudomonas lipase in phosphate-buffered saline (PBS, pH 7.4) at 37 degrees C . Tamoxifen loading over different concentrations was analyzed by high-performance liquid chromatography (HPLC) and the optimum loading concentration was determined . In vitro release studies were performed in 0.5% (w/v) sodium lauryl sulfate (SLS) containing PBS at 37 degrees C . Cellular uptake and distribution of fluorescent-labeled nanoparticles was examined in MCF-7 breast cancer cells . SEM micrographs and Coulter analysis showed nanoparticles with spherical shape and uniform size distribution (250-300 nm), respectively . Zeta potential analysis revealed a positive surface charge of +25 mV on the tamoxifen-loaded formulation . Being hydrophobic crystalline polyester, PCL did not degrade in PBS alone, but the degradation was enhanced by the presence of lipase . The maximum tamoxifen loading efficiency was 64% . Initial burst release of tamoxifen was observed, probably due to significant surface presence of the drug on the nanoparticles . A large fraction of the administered nanoparticle dose was taken up by MCF-7 cells through non-specific endocytosis . The nanoparticles were found in the perinuclear region after 1 h . Results of the study suggest that nanoparticle formulations of selective ER modulators, like tamoxifen, would provide increased therapeutic benefit by delivering the drug in the vicinity of the ER.

Environ Sci Technol, 2002 Nov 1, 36(21), 4585 - 92
Aerobic biodegradation of hopanes and other biomarkers by crude oil-degrading enrichment cultures; Frontera-Suau R et al.; The degradation of petroleum biomarkers was examined using mixed cultures of microorganisms enriched from surface soils at four different hydrocarbon-contaminated sites . These cultures degraded C30 17alpha(H),21beta(H)-hopane and the C31-C34 extended hopanes in Bonny Light crude oil after 21 days of incubation at 30 degrees C . The C35 extended hopanes were conserved, and no 25-norhopanes were detected during the incubation . Denaturing gradient gel electrophoresis (DGGE) analysis of the enrichment cultures demonstrated distinct microbial community profiles . Additional studies with the LC culture demonstrated a consistent biomarker degradation pattern after growth on three crude oils: a Nigerian Bonny Light crude, a Venezuelan crude oil, and Alaskan North Slope 521 . The onset of biomarker degradation was observed between days 14 and 21 but only at 30 degrees C and at oil concentrations below 6 mg/mL . The biomarker profiles following degradation by these enrichment cultures are similar to numerous field observations and may represent the dominant biodegradation pattern found in many hydrocarbon-contaminated aerobic surface environments.

Bioresour Technol, 2003 Jan, 86(1), 21 - 3
Biodegradation of wastepaper by cellulase from Trichoderma viride; van Wyk JP et al.; Environmental issues such as the depletion of non-renewable energy resources and pollution are topical . The extent of solid waste production is of global concern and development of its bioenergy potential can combine issues such as pollution control and bioproduct development, simultaneously . Various wastepaper materials, a major component of solid waste, were treated with the cellulase enzyme from Trichoderma viride, thus bioconverting their cellulose component into fermentable sugars . All wastepaper materials exhibited different susceptibilities towards the cellulase as well as the production of non-similar sugar releasing patterns when increasing amounts of paper were treated with a fixed enzyme concentration . The hydrolysis of wastepaper with changing enzyme concentrations and incubation periods also resulted in dissimilar sugar-producing tendencies . A general decline in hydrolytic efficiency was observed when increasing sugar concentrations were produced during biodegradation of all wastepaper materials.

Bioresour Technol, 2003 Jan, 86(1), 1 - 5
Starch-based plastic polymer degradation by the white rot fungus Phanerochaete chrysosporium grown on sugarcane bagasse pith: enzyme production; Roldan-Carrillo T et al.; In this study, starch metabolites and enzymes were determined during starch-based plastic polymer biodegradation by the white rot fungus Phanerochaete chrysosporium, grown in sugarcane bagasse pith in tubular reactors . Various metabolites, amylase, ligninase and cellulase production were measured during P . chrysosporium growth on sugarcane bagasse pith with added glucose and starch polymer . On-line respirometric analyses followed during 32 days confirmed the P . chrysosporium capability of growing on sugarcane bagasse pith with starch polymer degradation . Enzyme activity during secondary metabolism increased, and a 70% and 74% starch degradation was reached with and without glucose addition, generating low molecular weight metabolites (e.g.) dextrin, maltotriose, maltose and glucose that were detected by high performance liquid chromatography.

J Biomed Mater Res, 2002, 63(6), 772 - 9
Tissue reaction and biodegradation of implanted cross-linked high amylose starch in rats; Desevaux C et al.; The biocompatibility and degradation characteristics of cross-linked high amylose starch (Contramid were investigated in rats over 4 months . Contramid pellets (3-mm diameter and thickness) obtained by direct compression, were implanted subcutaneously and intramuscularly . On sequential time points, macroscopic observations of implantation sites were performed and tissue samples were removed, fixed, and histologically evaluated . No macroscopic inflammatory reaction was observed with Contramid. . Upon histologic examination, inflammatory reaction produced by Contramid was moderate and restricted to implantation sites . The sequence of inflammatory events with Contramid was similar regardless of implantation site . Degradation of Contramid pellets was characterized by fragmentation with formation of fibrovascular septa and phagocytosis by macrophages . Finally Contramid was mostly absorbed by the end of the 4-month period and substituted by adipocytes . It has been demonstrated that Contramid is a biocompatible and absorbable material .

Biomaterials, 2003 Jan, 24(1), 121 - 30
The influence of protein adsorption and surface modifying macromolecules on the hydrolytic degradation of a poly(ether-urethane) by cholesterol esterase; Jahangir R et al.; Previous investigations have demonstrated that the inflammatory cell derived enzyme, cholesterol esterase (CE) could degrade polyurethanes (PUs) by hydrolyzing ester and urethane bonds . Studies that have investigated the development of protective coatings for PUs have reported that the polymer degradation of polyester-urethanes (PESUs) can be reduced with the use of fluorine containing surface modifying macromolecules (SMMs) . Since these latter studies were carried out in the presence of relatively pure enzyme, it has not been shown if SMMs would still provide an enhanced inhibitory effect if surfaces were pre-exposed to plasma proteins . This would be more representative of the in vivo scenario since protein adsorption would occur before the appearance of monocyte-derived macrophages which would be a primary source of esterase activities . The current investigation has focused on studying the influence of fibrinogen (Fg) as a simple model of protein adsorption in order to assess the effect of CE in combination with protein on polyether-urethane (PEU) surfaces . The materials were prepared with and without SMMs, and were pre-coated with Fg prior to carrying out biodegradation studies . The pre-adsorption of Fg onto the modified and non-modified surfaces provided a significant delay in the hydrolytic action of CE onto the PEU substrates . However, the effect was gone by 70 days and by the 126th day of incubation, both Fg coated and non-Fg coated groups had the same level of degradation . The difference between Fg coated and non-coated substrates was much smaller for materials containing SMMs . In addition, the pre-adsorption of Fg did not alter the SMMs' ability to provide a more biostable surface over the 4 month incubation period .

J Environ Sci Health A Tox Hazard Subst Environ Eng, 2002 Nov, 37(10), 1871 - 8
The role of pH in mesophilic anaerobic sludge solubilization; Gomec CY et al.; The effect of pH on anaerobic solubilization of synthetic sludge (dog food) and domestic primary sludge was investigated and compared . Anaerobic solubilization was carried out in Continuously Stirred Anaerobic Reactors at mesophilic temperature (35 degrees C) and pH was fixed at 6.5 (pH-controlled) . The aim of pH control in the reactors consisting of synthetic and primary sludge, was the evaluation of retardation in hydrolysis/acidogenesis at low pH values . Since synthetic and primary sludge have different biodegradation characteristics, the results were compared . In both sludges, acetic acid was the main Volatile Fatty Acids (VFAs) produced . Volatile Suspended Solid (VSS) reduction was found as 67% in about 20 days in the anaerobic digestion of synthetic sludge . whereas for the same interval VSS reduction could only be achieved by 32% in primary sludge at 35 degrees C in the pH-controlled reactors . When both types of sludges were used as substrates, the reactors removed VSS with a corresponding production of VFAs and Soluble Chemical Oxygen Demand (SCOD) . However, in the pH-controlled reactors production of VFAs and SCOD was ceased after 5 days in primary sludge whereas VFAs and SCOD production continued after 5 days in synthetic sludge which indicated that hydrolysis and fermentation in the anaerobic solubilization reactors were not complete and continued longer . On the other hand, in the pH-controlled reactor of primary sludge, methanogenic phase could operate after 5 days of operation as hydrolysis/acidogenesis stopped.

J Hazard Mater, 2002 Nov 11, 95(1-2), 91 - 106
Biodegradation of RDX within soil-water slurries using a combination of differing redox incubation conditions; Waisner S et al.; Biodegradation of 14C-tagged hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) was studied in aerobic, anaerobic, and anaerobic/aerobic slurries to identify the conditions maximizing RDX-mineralization in Cornhusker Army Ammunition Plant (CAAP, NE) groundwater . Supplementation with phosphate and adequate quantities of acetate caused 25% mineralization of RDX in 3 weeks by microorganisms native to CAAP . Under anaerobic conditions, the same supplementation resulted in 20% mineralization in 3 weeks and 30% mineralization in 6 weeks . The highest degree of mineralization (50%) was obtained under aerobic conditions when the contaminated groundwater was augmented with a consortium of three microbes isolated from another RDX contaminated soil (Hastings, NE) in addition to supplemented with phosphate and acetic acid . Use of complex organic sources (potato or corn starch) slowed down the rates of mineralization under anaerobic conditions, but rapid mineralization ensued as soon as the aerobic conditions were created . Final RDX concentrations in aqueous phase were below detection limit under most conditions . Assimilation of RDX by the cells was negligible.

J Contam Hydrol, 2002 Oct, 58(3-4), 191 - 207
pH-Dependent fate and transport of NTA-complexed cobalt through undisturbed cores of fractured shale saprolite; Brooks SC et al.; The codisposal of toxic metals and radionuclides with organic chelating agents has been implicated in the facilitated transport of the inorganic contaminants away from primary waste disposal areas . We investigated the transport of Co(II)NTA through undisturbed cores of fractured shale saprolite . Experiments were conducted across the pH range 4 to 8 by collecting cores from different locations within the weathering profile . Aqueous complexation, adsorption, dissociation and oxidation reactions influenced Co(II)NTA transport . The suite of reaction products identified in column effluent varied with experimental pH . At low pH and in the presence of abundant exchangeable aluminum, Co transport occurred predominantly as the Co2+ ion . At higher pH, Co was transported primarily as Co(II)NTA and the Co(III) species Co(III)(HNTA)2 and Co(III)(IDA)2 . The formation of the geochemical oxidation products (Co(III) species) has far reaching implications as these compounds are kinetically and thermodynamically stable, are transported more rapidly than Co(II)NTA, and are resistant to biodegradation . These results demonstrate that natural minerals, in the physical structure encountered naturally, can be more important in the formation of mobile, stable contaminant forms than they can be for the retardation and dissociation of the contaminants.

Mar Pollut Bull, 2002, 45(1-12), 316 - 24
Preliminary study on biodegradation of phenanthrene by bacteria isolated from mangrove sediments in Hong Kong; Tam NF et al.; Elevated concentrations of polycyclic aromatic hydrocarbons (PAHs) have been found in mangrove sediments due to anthropogenic pollution, and microbial degradation has been suggested as the best way to remove PAHs from contaminated sediments . The degradation of phenanthrene, a model PAH compound by bacteria, either the enriched mixed culture or individual isolate isolated from surface mangrove sediments was examined . The effects of salinity, initial phenanthrene concentrations and the addition of glucose on biodegradation potential were also investigated . Results show that surface sediments collected from four mangrove swamps in Hong Kong had different degree of PAH contamination and had different indigenous phenanthrene-degrading bacterial consortia . The enriched bacteria could use phenanthrene as the sole carbon source for growth and degrade this PAH compound accordingly . A significant positive relationship was found between bacterial growth and percentages of phenanthrene degradation . The phenanthrene biodegradation ability of the enriched mixed bacterial culture was not related to the degree of PAH contamination in surface sediments . The growth and biodegradation percentages of the enriched mixed culture were not higher than that of the individual isolate especially at low salinity (0 and 10 ppt) . High salinity (35 ppt) inhibited growth and biodegradation of phenanthrene of a bacterial isolate but less inhibitory effect was found on the mixed culture . The inhibitory effects of salinity could be reduced with the addition of glucose.

J Microencapsul, 2002 Jul-Aug, 19(4), 523 - 35
Poly(DL-lactide-co-glycolide) microporous microsphere-based depot formulation of a peptide-like antineoplastic agent; Shenoy DB et al.; In the present investigation, a poly(DL-co-glycolide) (PLGA)-based, microspheric depot system for bleomycin (BLM) has been formulated, and the same has been evaluated in-vivo in C57BL/6J mice bearing transplantable melanoma B16F1 murine solid tumour . The microparticulate delivery systems were formulated employing a water-in-oil-in-water (W/O/W) emulsion-solvent evaporation technique and characterized in-vitro . The microspheres were injected subcutaneously to form a drug depot at the site of injection in mice bearing experimental tumours and the drug was continuously infused into the systemic circulation with progressive biodegradation . The drug-loaded microspheres exhibited improved pharmacodynamic efficacy, as evidenced by retarded tumour growth kinetics . Preliminary pharmacokinetic studies illustrated controlled release of the drug into the systemic circulation over the study period to exert an anti-neoplastic action . These studies demonstrated the feasibility of employing a PLGA-based microparticulate system as an effective biodegradable, injectable, depot-forming therapeutic system for long-term administration of anti-neoplastic agents.

J Appl Microbiol, 2002, 93(5), 810 - 6
Kytococcus sedentarius, the organism associated with pitted keratolysis, produces two keratin-degrading enzymes; Longshaw CM et al.; AIMS: To determine characteristics of the extracellular enzyme activity of Kytococcus sedentarius on human callus . METHODS AND RESULTS: A concentrate of a continuous culture supernatant fluid of K . sedentarius, which had callus-degrading activity, was subjected to a series of chromatographic purification procedures . The enzyme activity was found to be attributable to two proteases . These were capable of degrading both native callus and extracted keratin polypeptides and were purified to homogeneity, as shown by SDS-PAGE with silver staining . The enzymes P1 and P2 were 30 kDa and 50 kDa in size with isoelectric points of 4.6 and 2.7, respectively . The optimum conditions for callus-degrading activity were 40 degrees C, pH 7.1 for P1 and 50 degrees C, pH 7.5 for P2 . P2 displayed increased activity in the presence of 800 mmol l(-1) NaCl and both enzymes were inhibited by PMSF (1 mmol(-1) Phenylmethylsulphoryl fluoride) and 1 mmol l(-1) EDTA . The main enzyme cleavage sites were Lys-Trp, Val-Lys, Gly-Asp and Asp-Arg, as determined after incubation of P1 and P2 with the beta-chain of insulin . CONCLUSIONS: K . sedentarius produces two extracellular enzymes that independently degrade natural, insoluble human callus . Both enzymes are serine proteases and have cleavage preference sites that are present in a range of human keratins . SIGNIFICANCE AND IMPACT OF THE STUDY: The identification, in K . sedentarius cultures, of two enzymes which can degrade human callus strengthens the hypothesis that this organism is responsible for the pitting in human epidermis observed in pitted keratolysis . These enzymes may be of commercial use in the biodegradation of a range of keratin polymers, biological washing powders and in the treatment of unwanted callus on human skin.

Adv Drug Deliv Rev, 2002 Oct 16, 54(7), 933 - 61
Toxicity, biodegradation and elimination of polyanhydrides; Katti DS et al.; Although originally developed for the textile industry, polyanhydrides have found extensive use in biomedical applications due to their biodegradability and excellent biocompatibility . Polyanhydrides are most commonly synthesized from diacid monomers by polycondensation . Efficient control over various physicochemical properties, such as biodegradability and biocompatibility, can be achieved for this class of polymers, due to the availability of a wide variety of diacid monomers as well as by copolymerization of these monomers . Biodegradation of these polymers takes place by the hydrolysis of the anhydride bonds and the polymer undergoes predominantly surface erosion, a desired property to attain near zero-order drug release profile . This review examines the mode of degradation and elimination of these polyanhydrides in vivo as well as the biocompatibility and toxicological aspects of various polyanhydrides.

Adv Drug Deliv Rev, 2002 Oct 18, 54(8), 1075 - 91
Genetically engineered silk-elastinlike protein polymers for controlled drug delivery; Megeed Z et al.; The silk-elastinlike class of genetically engineered protein polymers is composed of tandemly repeated silk-like (Gly-Ala-Gly-Ala-Gly-Ser) and elastin-like (Gly-Val-Gly-Val-Pro) amino acid blocks . The precision with which these polymers can be synthesized, as well as the ability to incorporate motifs that allow for gel-formation, stimuli-sensitivity, biodegradation, and biorecognition have stimulated interest in their use for controlled drug and gene delivery . This review will focus on the synthesis and characterization of silk-elastinlike polymers as related to controlled drug delivery . The design and biological synthesis of the copolymers, by recombinant DNA techniques, are reviewed . The characterization of the polymers is discussed . Finally, biocompatibility of the polymers and recent studies to determine their potential utility for controlled drug and gene delivery are reviewed.

Water Sci Technol, 2002, 46(6-7), 317 - 24
Onsite wastewater differential treatment system: modeling approach; Lopez Zavala MA et al.; In this paper, the Onsite Wastewater Differential Treatment System (OWDTS), a new approach for improving the traditional onsite wastewater treatment systems (OWTS), is proposed based on differential management and treatment of household wastewater effluents . Three fractions of household wastewater have been differentiated, reduced-volume blackwater, higher-load graywater and lower-load graywater . Based on this differentiation, different treatment processes required for each fraction are discussed . The procedure adopted for treatment of toilet wastes (reduced-volume blackwater) is shown . In the case of graywater, a sketch of treatment processes is provided . The OWDTS seems to be a new approach with higher potential for improvement of traditional OWTS, dry ecological sanitation, recycling of resources (toilet wastes and water), conservation of water resources, etc . Aerobic biodegradation of toilet wastes by using sawdust as a matrix is an essential treatment process of the OWDTS . Membrane technology seems to be the most effective process to treat higher-load gray water . Natural biodegradation of lower-load gray water by soil bacteria needs to be deeply studied.

Environ Toxicol Chem, 2002 Oct, 21(10), 2052 - 8
Aerobic degradation of ethyl-tert-butyl ether by a microbial consortium: selection and evaluation of biodegradation ability; Kharoune M et al.; A microbial consortium that degrades ethyl-tert-butyl ether (ETBE) as the sole source of carbon and energy under aerobic conditions was selected from a gasoline-polluted soil . This consortium consists of a variety of microorganisms with a predominance of filamentous morphology . Degradation of ETBE was found to be solely related to bacterial activity . After prolonged cultivation followed by successive transfers, the consortium's degradation ability was improved and reached a specific degradation rate of 95 mg/g(protein)/h (about 146 mg/g(dry wt)/h) . This exceeds the previously reported rates in the literature for ETBE-degrading microorganisms as pure or mixed cultures . Furthermore, a stoichiometric balance of chemical oxygen demand (COD) removal and oxygen uptake with ETBE removal provides indirect evidence of complete degradation . The consortium's activity was not inhibited by high ETBE concentrations (< or = 1,600 mg/L), and large inoculum sizes (> or = 120 mg(protein)/L) were desirable for a faster and complete degradation of ETBE . The enriched consortium was also able to completely degrade methyl-tert-butyl ether (MTBE), tert-amyl methyl ether (TAME), and tert-butyl alcohol (TBA) . both alone and in mixture with ETBE, without any measurable release of major degradation intermediates . In each case, MTBE and TAME exhibited the most significant resistance to degradation while TBA was rapidly degraded.

Water Res, 2002 Sep, 36(15), 3821 - 33
Behavior of a chemically dispersed oil in a wetland environment; Page CA et al.; An experiment was conducted at a wetland research facility, investigating the behavior and effects of chemically dispersed oil (CDO) using an oil-spill dispersant . The research site is located on the San Jacinto River near Houston, TX . The replicated treatments included oiled control, "high-dose" CDO (1:10 dispersant-to-oil ratio (DOR)), "low-dose" CDO (1:20 DOR), as well as an unoiled control . Known amounts of oil or dispersed oil were added to the respective plots . Sediment samples were taken over a 99-day period using a 5-cm-diameter coring device . The GC/MS results for both "total target saturate hydrocarbons" and "total target aromatic hydrocarbons" were plotted over time and data were modeled using nonlinear regression . The overall (including abiotic and biotic) petroleum loss rates for the dispersed-oil treatments were not statistically different when compared to the oiled control . However, the initial concentrations for the dispersed-oil treatments were statically lower (95% confidence) than for the oiled control . From this, it can be inferred that the dispersed oil was more prone to flush off the sediments, as was visually observed . Biodegradation rates were also determined for all treatments; it was concluded that there were no differences when comparing each dispersed-oil treatment to the oiled control . The sediments from each plot were also analyzed for microbial population numbers (most-probable-number) and acute toxicity (Microtox 100% Test) . Statistical analyses for both sets of data found no significant differences for the dispersed-oil treatments when compared to the oiled control.

Water Res, 2002 Sep, 36(15), 3739 - 46
Effect of ethanol on BTEX biodegradation kinetics: aerobic continuous culture experiments; Lovanh N et al.; The use of ethanol as an automotive fuel oxygenate represents potential economic and air-quality benefits . However, little is known about how ethanol may affect the natural attenuation of petroleum product releases . Chemostat experiments were conducted with four pure cultures (representing archetypes of the known aerobic toluene degradation pathways) to determine how ethanol affects benzene, toluene, ethylbenzene, and xylene (BTEX) biodegradation kinetics . In all cases, the presence of ethanol decreased the metabolic flux of toluene (measured as the rate of toluene degradation per cell) . This negative effect was counteracted by an ethanol-supported increase in biomass, which is conducive to faster degradation rates . When the influent total organic carbon (TOC) of the toluene-ethanol mixture was kept constant, the metabolic flux of toluene was proportional to its relative contribution to the influent TOC . This empirical relationship was used to derive a mathematical model that simulated effluent benzene concentrations as a function of the influent mixed-substrate composition, the dilution rate, and Monod kinetic coefficients . Under carbon-limiting conditions (1 mg/L influent benzene), the data and model simulations showed an increase in benzene removal efficiency when ethanol was fed at low concentrations (ca . 1 mg/L) because its positive effect on cell growth outweighed its negative effect on the metabolic flux of benzene . High ethanol concentrations, however, had a negative effect, causing oxygen limitation and increasing effluent benzene concentrations to higher levels than when benzene was fed alone . The slower BTEX degradation rates expected at sites with high ethanol concentrations (e.g., at gasohol-contaminated sites) could result in longer BTEX plumes and a greater risk of exposure.

Bioresour Technol, 2002 Dec, 85(3), 263 - 72
A potential resource for bioconversion of domestic wastewater sludge; Molla AH et al.; Twenty seven filamentous fungal strains representing five genera; Aspergillus, Penicillium, Trichoderma, Myriodontium and Pleurotus were isolated from four sources; domestic wastewater sludge cake (SC) from IWK (Indah Water Konsortium) wastewater treatment plant, palm oil mill effluent compost from Sri Ulu palm Oil Processing Mill, compost of plant debris, and fungal fruiting bodies from a rotten wood stump . Thirty-three strains/isolates were tested for their ability to convert domestic wastewater sludge into compost by assessing biomass production and growth rate on sludge enriched media . The strains/isolates Aspergillus niger, SS-T2008, WW-P1003 and RW-P1 512 produced the highest dry biomass at higher sludge supplemented culture media from their respective group (Aspergillus, Trichoderma, Penicillium and Basidiomycetes, respectively) . This implied these strains are better adapted for growth at higher sludge rich substances, and subsequently may be efficient in bioconversion/biodegradation of sludge . The fungi isolated from ecological closely related sources were more amendable to adaptation in a sludge rich culture media.

Chemosphere, 2002 Nov, 49(5), 493 - 8
Effects of bacterial counts and temperature on the biodegradation of bisphenol A in river water; Kang JH et al.; Total 15 surface river waters were collected from thirteen different rivers to investigate a relationship of bacterial counts and temperature to the degradation of bisphenol A (BPA) . Autoclaved and non-autoclaved river water samples were spiked with 0.2 mg/l BPA . The spiked samples were placed at temperatures of 4, 20, and 30 degrees C and analyzed by high performance liquid chromatography . BPA was degraded at all temperatures in the non-autoclaved samples . However, BPA in the autoclaved samples was not changed at all temperatures for 20 d . These results show that the primary factor of BPA degradation in river water is bacteria . Moreover, three groups {group A (> 10000 CFU/ml), group B (2000-10000 CFU/ml), and group C (< 2000 CFU/ml)}, were made on the basis of bacterial counts of the samples . Half-lives for BPA degradation in groups A, B, and C were 2, 3, and 6 d at 30 degrees C and were 4, 5, and 7 d at 20 degrees C, respectively . But at 4 degrees C, the loss of BPA was about 40%, 20%, and 10% in groups A, B, and C for 20 d, respectively . Bacterial counts exerted an influence on BPA degradation in river water with temperature . Our results also show that BPA-degrading bacteria are widely distributed in river waters.

Chemosphere, 2002 Oct, 49(3), 297 - 306
Biodegradation of aromatic compounds by white rot and ectomycorrhizal fungal species and the accumulation of chlorinated benzoic acid in ectomycorrhizal pine seedlings; Dittmann J et al.; The capability of different white rot (WR, Heterobasidion annosum, Phanerochaete chrysosporium, Trametes versicolor) and ectomycorrhizal (ECM, Paxillus involutus, Suillus bovinus) fungal species to degrade different aromatic compounds and the absorption of 3-chlorobenzoic acid (3-CBA) by ECM pine seedlings was examined . The effect of aromatic compounds on the fungal biomass development varied considerably and depended on (a) the compound, (b) the external concentration, and (c) the fungal species . The highest effect on the fungal biomass development was observed for 3-CBA . Generally the tolerance of WR fungi against aromatic compounds was higher than that of the biotrophic fungal species . The capability of different fungi to degrade aromatic substances varied between the species but not generally between biotrophic and saprotrophic fungi . The highest degradation capability for aromatic compounds was detected for T . versicolor and H . annosum, whereas for Phanerochaete chrysosporium and the ECM fungi lower degradation rates were found . However, Paxillus involutus and S . bovinus showed comparable degradation rates at low concentrations of benzoic acid and 4-hydroxybenzoic acid . In contrast to liquid cultures, where no biodegradation of 3-CBA by S . bovinus was observed, mycorrhizal pines inoculated with S . bovinus showed a low capability to remove 3-CBA from soil substrates . Additional X-ray microanalytical investigations showed, that 3-CBA supplied to mycorrhizal plants was accumulated in the root cell cytoplasm and is translocated across the endodermis to the shoot of mycorrhizal pine seedlings.

Environ Technol, 2002 Sep, 23(9), 1075 - 9
A self-regulated fed-batch reactor part I--the principle; Santana FJ et al.; A new fed-batch reactor was developed to conduct aerobic biodegradation studies . Its unique feature lies in the ability to self-regulate feed addition, according to the evolution of the degradation process, which is proportional to gaseous products formed, mainly CO2 . The reactor is particularly well suited to evaluate intrinsic biokinetic parameters, since it allows to be reached equilibrium states (substrate-biomass) . Application to kinetic studies of inhibitory or toxic compounds seems to be quite promising given that feed is made dependent on the capacity and pace of the biomass to handle the degradation of such compounds.

Water Sci Technol, 2002, 46(4-5), 215 - 21
Start-up of a pilot-scale anaerobic fixed film reactor at low temperature treating slaughterhouse wastewater; del Pozo R et al.; A pilot-scale anaerobic fixed film reactor (AFFR) with vertically arranged PVC tubes as biomass carrier, treating poultry slaughterhouse wastewater was started-up in 74 days at temperatures between 20-24 degrees C . The start-up process consisted of a long acclimatization phase followed by a low loaded growth phase, a gradual increase of OLR upto 9.2 kg COD/m3d, and a final maturation phase at moderated loads of 2.7 kg COD/m3d at which total COD removal efficiencies of 57% were achieved . Alkalinity ratio IA:PA was found to be the best control parameter to avoid VFA accumulation . OLR increase based on pH control was not satisfactory because changes in CO2 solubility caused daily by temperature and flow variations led to pH oscillations of 0.2 units . The low wastewater alkalinity, 260 mg/l CaCO3 was insufficient to buffer the pH system, therefore the pH decrease associated with the VFA accumulation was not easily detected and could not be used as a way of OLR control . Organic matter removal took place by accumulation and biodegradation processes . Limitation in the reactor hydrodynamics and particulate fraction hydrolysis was detected at high flow rates.

Biochem Biophys Res Commun, 2002 Oct 4, 297(4), 918 - 23
A selective lignin-degrading fungus, Ceriporiopsis subvermispora, produces alkylitaconates that inhibit the production of a cellulolytic active oxygen species, hydroxyl radical in the presence of iron and H(2)O(2); Watanabe T et al.; A cellulolytic active oxygen species, hydroxyl radicals (.OH), play a leading role in the erosion of wood cell walls by brown-rot and non-selective white-rot fungi . In contrast, selective white-rot fungi have been considered to possess unknown systems for the suppression of .OH production due to their wood decay pattern with a minimum loss of cellulose . In the present paper, we first report that 1-nonadecene-2,3-dicarboxylic acid, an alkylitaconic acid (ceriporic acid B) produced by the selective white-rot fungus Ceriporiopsis subvermispora intensively inhibited .OH production by the Fenton reaction by direct interaction with Fe ions, while non-substituted itaconic acid promoted the Fenton reaction . Suppression of the Fenton reaction by the alkylitaconic acid was observed even in the presence of the Fe(3+) reductants, cysteine and hydroquinone . The inhibition of .OH production by the diffusible fungal metabolite accounts for the extracellular system of the fungus that attenuates the formation of .OH in the presence of iron, molecular oxygen, and free radicals produced during lignin biodegradation.

Lett Appl Microbiol, 2002, 35(4), 296 - 300
The characterization of oil-degrading microorganisms from lubricating oil contaminated (scale) soil; Jirasripongpun K; AIMS: To isolate and characterize oil-degrading microorganisms from contaminated (scale) soil . METHODS AND RESULTS: Oil-degrading microorganisms were isolated from enrichment cultures of scale soil . Each isolate was identified using 16S rDNA gene and oil degradability was determined on both unused and used lubricating oil . The weight of the extracted remaining oil revealed that most isolates degraded unused lubricating oil more than used lubricating oil . Chemical composition of oil analysed by TLC-FID and GC-MS demonstrated that Nocardia simplex W9 degraded used oil the best, and resulted in a decrease in saturates, aromatics and resins to 52.46, 38.13 and 18.81%, respectively . CONCLUSIONS:Nocardia simplex W9 is the best degrader, among all the isolates, on both used and unused lubricating oil . SIGNIFICANCE AND IMPACT OF THE STUDY: The presence of Nocardia simplex W9 in scale soil enables iron to be recycled by biodegradation.

Hypotenuse . 1985 May-Jun;:2-5.
Capronor; Research Triangle Institute; PIP: In 1979, after 6 years of research, development, and testing, the Research Triangle Institue (RTI) was awarded a patent for the contraceptive implant, Capronor . The implant's inch long tube is filled with levonorgestrel, a synthetic progestogen, and is injected into a woman's upper arm or hip . It delivers a steady levonorgestrel dose for 1 year, then begins to decompose . Its advantages include 1) user ease, and 2) steady drug release levels . 1 month trials show no discomfort and constant hormone level maintenance . This initial trial will be followed by month long clinical studies in London, Bangkok, and Rome, and by 1 year long tests by 400 women at 20 research centers around the world . The capsule's polymer is ideally suited for implant use, unlike some nonbiodegradable implants in use, since it slowly disintegrates after a year and is excreted from the body . Clinical trials since 1980 show Capronor to be safe and effective; after future tests, Capronor can be submitted to the US Federal Drug Administration for approval . Controlled drug release systems work in 1 of 3 ways: 1) diffusion through a semipermeable polymer membrane (which is how Capronor works), 2) use of a porous polymer, and 3) biodegradation . Some researchers are now working on self-regulated systems which release drugs in response to biological need, instead of a steady, predetermined, unchangeable rate . Biological delivery systems differ from synthetic devices because they can target specific tissues and automatically regulate the supply of the active agent in proportion to the biological need . RTI researchers are currently testing 2 approaches to self-regulated drug delivery: 1) using antibodies and binding proteins to control polymer membrane permeability and biodegradability, and 2) using chelation (a process that forms a ring structure containing a metal ion) functioning drugs whose release is controlled by a target metal . Continuing research will allow existing drugs to be delivered in new, different, more effective, and safer ways .

Appl Environ Microbiol, 2002 Oct, 68(10), 5181 - 5
Free-living heterotrophic nitrogen-fixing bacteria isolated from fuel-contaminated antarctic soils; Eckford R et al.; Five bacterial isolates enriched from fuel-contaminated Antarctic soils fixed nitrogen in the dark heterotrophically and nonsymbiotically . Two isolates utilized jet fuel vapors and volatile hydrocarbons for growth but not in N-deficient medium . Bacteria such as these may contribute to in situ biodegradation of hydrocarbons in Antarctic soils.

Appl Environ Microbiol, 2002 Oct, 68(10), 4841 - 6
Identification of a hydratase and a class II aldolase involved in biodegradation of the organic solvent tetralin; Hernaez MJ et al.; Two new genes whose products are involved in biodegradation of the organic solvent tetralin were identified . These genes, designated thnE and thnF, are located downstream of the previously identified thnD gene and code for a hydratase and an aldolase, respectively . A sequence comparison of enzymes similar to ThnE showed the significant similarity of hydratases involved in biodegradation pathways to 4-oxalocrotonate decarboxylases and established four separate groups of related enzymes . Consistent with the sequence information, characterization of the reaction catalyzed by ThnE showed that it hydrated a 10-carbon dicarboxylic acid . The only reaction product detected was the enol tautomer, 2,4-dihydroxydec-2-ene-1,10-dioic acid . The aldolase ThnF showed significant similarity to aldolases involved in different catabolic pathways whose substrates are dihydroxylated dicarboxylic acids and which yield pyruvate and a semialdehyde . The reaction products of the aldol cleavage reaction catalyzed by ThnF were identified as pyruvate and the seven-carbon acid pimelic semialdehyde . ThnF and similar aldolases showed conservation of the active site residues identified by the crystal structure of 2-dehydro-3-deoxy-galactarate aldolase, a class II aldolase with a novel reaction mechanism, suggesting that these similar enzymes are class II aldolases . In contrast, ThnF did not show similarity to 4-hydroxy-2-oxovalerate aldolases of other biodegradation pathways, which are significantly larger and apparently are class I aldolases.

Eur J Vasc Endovasc Surg, 2002 Oct, 24(4), 314 - 21
Fresh arterial homograft transplantation: a novel concept for critical limb ischaemia; Prager M et al.; INTRODUCTION: homografts have been used since the early days of vascular surgery, but have failed to provide long-term success . Arteries supplying organ transplants seldom show signs of biodegradation . We therefore introduced fresh arterial homograft repair with consecutive immunosuppression (ATX) . AIM: to assess feasibility and clinical usefulness of ATX . SETTING: university teaching hospital . MATERIAL AND METHOD: conduits were harvested during multi-organ procurement and stored in Custodiol . Implantation followed immediately . Viability of the transplant was documented in all cases . Patients received immunosuppression for the duration of bypass function . RESULTS: thirteen patients received ATX for critical limb ischaemia (M/F: 11/2, age: 62yr, previous revascularisations: 4.5 (1-8), median run-off index 5, previous organ transplant: n=2 . Most bypasses were anastomosed to single tibial or pedal vessels . There was no early failure . Within an average follow up of 12 months there were 6 graft thromboses in 5 patients, successfully revised in 4 . Three limbs were lost after 2, 5 and 6 months due to graft failure . Graft rejection was shown in 1 out of 3 explanted grafts . CONCLUSION: we report a concept, which may circumvent the problem of biologic graft degeneration . Limb salvage was possible in 75% at 12 months in otherwise difficult circumstances.

Biomaterials, 2002 Dec, 23(23), 4621 - 31
Synthesis and biodegradation of arabinogalactan sponges prepared by reductive amination; Ehrenfreund-Kleinman T et al.; The synthesis of polysaccharide-based sponges for the use in tissue engineering was systematically investigated . A comparison study of the branched polysaccharide arabinogalactan (AG) and the linear polysaccharide dextran in the formation of sponges by the reaction with diamines or polyamines was conducted . Three AG-based sponges were synthesized from the crosslinking reaction with different amine molecules . The sponges obtained were highly porous, rapidly swelled in water, and were stable in vitro for at least 11 weeks in aqueous media at 37 degrees C . AG-chitosan sponges were chosen as most suitable to serve as scaffolds for cell growth in tissue engineering . The biocompatibility in vivo of these sponges was evaluated by histological staining and non-invasive MRI technique after implantation in BALB/c mice . The sponge evoked an inflammatory response with vascularization of the implant . The inflammatory reaction decreased with time, indicating a healing process.

Biomaterials, 2002 Dec, 23(23), 4591 - 600
Skeletal repair in rabbits with calcium phosphate cements incorporated phosphorylated chitin; Wang X et al.; The effects of phosphorylated chitin (P-chitin) on the tissue responses to two kinds of calcium phosphate cements (CPCs) were investigated using experimental rabbits . One of them consisting of monocalcium phosphate monohydrate, calcium oxide, 1 M phosphate buffer (pH: 7.4) and different amounts of P-chitin (CPC-I or P-CPC-I) with relatively neutral initial pH was filled as paste into tibial defects of the rabbits for 1, 4, 12 and 22 weeks . The other kind of cement made from dicacium phosphate dihydrate/calcium hydroxide/1 M Na2HPO4/different amounts of P-chitin (CPC-II or P-CPC-II) with relatively higher initial pH was implanted as prehardened cylinders into the radial defects of the rabbits for the same periods . Pure CPC-I and CPC-II were used as controls . Histological and histomorphological studies were performed on thin un-decalcified and decalcified sections . Three different bone formation types in the resorption lacuna of the P-CPCs were found during this study . The biodegradation rate of the P-CPCs had a negative relationship with the P-chitin content . Most of the low P-chitin-containing samples were bioabsorbed in 16 weeks, while the high P-chitin-containing samples disappeared in 22 weeks . The newly formed bone was identified with back scattered scanning electron microscopy and X-ray energy-dispersive spectrometry . The results show that with P-chitin component in a certain range, the P-CPCs are biocompatible, bioabsorbable and osteoinductive and could be used as promising candidates of bone repair materials.

Biomaterials, 2002 Dec, 23(23), 4459 - 62
Novel sustained-release implant of herb extract using chitosan; Zhao HR et al.; Chitosan (CS), a naturally occurring high-molecule polymer, which is stable in vivo, has proved to be a useful biomaterial . The extract of danshen (Radix Salviae miltiorrhizae), a medicinal herbal, was developed with CS-gelatin as an implant for the promotion of anastomosing and healing on muscles and tissues at the organic incision site in abdominal cavities . Measurements were made of the sustained release of tanshinone IIa, a marker component, from the material in vitro . The dissolution medium was assayed with an high-performance liquid chromatography method . Biodegradation studies of the material were also conducted both in vitro and in vivo . The film made of this material exhibited a sustained release effect . The release profile confirms to the Higuchi equation . At most about 20% of the incorporated drug were released over 15 days in a CS-gelatin (1:2) matrix . Drug release was found to be effectively controlled by the drug-amount loaded in the matrix . The improved film (CS/gelatin ratio: 1:16) can be hydrolyzed by lysozymes in vitro in 4 days . This film of 0.5 cm2 was implanted and degraded completely in rats over 28 days and the animals' wounds of abdominal incision healed well.

Aquat Toxicol, 2002 Nov 13, 61(1-2), 127 - 40
Tolerance to biodegraded crude oil in marine invertebrate embryos and larvae is associated with expression of a multixenobiotic resistance transporter; Hamdoun AM et al.; The toxicity of water-soluble fractions of biodegraded crude oil (BWSF) to embryos and larvae of two marine invertebrates, the white sea urchin (Lytechinus anamesus) and the fat innkeeper (Urechis caupo), was studied . Santa Barbara Channel crude oil was artificially weathered and subjected to biodegradation using a mixed microbe culture obtained from natural oil seep sites . The degradation culture inoculated with seep sediment microbes accumulated 43.7 microg/l water-soluble hydrocarbons . In contrast water-soluble fractions from the non-degraded cultures (NWSF) only accumulated 3.05 microg/l . BWSF proved deleterious to Lytechinus embryo development at low concentrations (EC50 = 0.33 mg/l) but was essentially non-toxic to Urechis embryos/larvae up to 3.0 mg/l . An established mechanism for handling of a wide array of xenobiotics in Urechis embryos is the multixenobiotoic resistance transporter multixenobiotic response (MXR, also known as multidrug resistance, MDR) . This mechanism is primarily mediated by ATP-dependent, efflux pumps that extrude a wide array of xenobiotic compounds . In this study, we show that Lytechinus larvae do not appear to express MXR efflux protein nor MXR mediated dye efflux capacity . In contrast, BWSF acts as a competitive inhibitor of MXR transport-mediated dye efflux in Urechis larvae . These results suggest that MXR may be an important mechanism for extrusion of the by-products of crude oil degradation by microbes, and that the level of its expression may determine the susceptibility of organisms to degraded oil hydrocarbons .

Artif Organs, 2002 Oct, 26(10), 883 - 90
Biodegradation and biocompatibility of polyorganophosphazene; Kawakami H et al.; We investigated biodegradation and biocompatibility of poly(organophosphazenes) . We prepared poly(organophosphazenes) having different side chain groups . The blood compatibility of poly(organophosphazenes) containing fluorinated side groups, poly(bis{trifluoroethoxy}phosphazene) (PbFP) and poly({trifluoroethoxy}{ethyl glycinate}phosphazene) (PFGP), without heparinization were evaluated in vitro . The deformation and aggregation of platelets adhered on PbFP and PFGP were not observed and they suppressed platelet activation . Additionally, PbFP and PFGP showed a higher degradation rate, despite their high hydrophobic nature . We found that the high mobility of water in PbFP and PFGP was one of the important factors facilitating their degradation . Their polymer structures were formed in a more open nature, indicating that water easily attacked the backbone of the phosphorus and nitrogen atoms in the poly(organophosphazene) . On the other hand, the proliferation of HeLa cells cultured on poly(organophosphazene) was reduced compared with that on the control tissue culture polystyrene.

Int J Artif Organs, 2002 Aug, 25(8), 777 - 82
Biodegradable polymer (D,L-lactide-epsilon-caprolactone) in aortic vascular prosthesis: morphological evaluation in an animal model; Valente M et al.; Biodegradable D,L-Lactide-epsilon-caprolactone copolymer was used in substitution to bovine collagen to seal porosity in nine Dacron vascular Sorin Carbografts . One served as control and 8 were implanted in mini-pigs as vascular by-pass in the thoracic aorta . The grafts were explanted at 7 days (4 animals), 30 (2 animals) and at 90 days (2 animals), and submitted to gross examination, X-ray, histology and electron microscopy . Aim of the study was to assess the safety and the reliability of these polyester vascular prostheses impregnated with the copolymer in terms of containment of the bleeding in the perioperative period, host inflammatory response, copolymer biodegradation and prostheses "healing" All the grafts were patent at angiographic and X-ray examination . At 7 days blood infiltration between Dacron and copolymer lining was detected . Inflammatory granulocyte infiltrates and granulomatous reaction with polymer degradation was observed at 30 days and fibrous tissue healing at 90 days . Luminal surface was covered by thin thrombi at 7 and by a neointima at 30 and 90 days . We conclude that D,L-Lactide-epsilon-caprolactone copolymer is effective in preventing perigraft bleeding, even though an early hematoma between Dacron and the copolymer coating occurs . Copolymer is degraded through a mild inflammatory reaction, with eventual evolution to fibrous healing.

Mar Pollut Bull, 2002 Aug, 44(8), 789 - 806
Toxicological and chemical assessment of ordinance compounds in marine sediments and porewaters; Nipper M et al.; Toxicological and chemical studies were performed with a silty and a sandy marine sediment spiked with 2,6-dinitrotoluene (2,6-DNT), 2,4,6-trinitrophenylmethylnitramine (tetryl), or 2,4,6-trinitrophenol (picric acid) . Whole sediment toxicity was analyzed by the 10-day survival test with the amphipod Ampelisca abdita, and porewater toxicity tests assessed macro-algae (Ulva fasciata) zoospore germination and germling growth, sea urchin (Arbacia punctulata) embryological development, and polychaete (Dinophilus gyrociliatus) survival and reproduction . Whole sediments spiked with 2,6-DNT were not toxic to amphipods . The fine-grained sediment spiked with tetryl was also not acutely toxic . The tetryl and picric acid LC50 values in the sandy sediment were 3.24 and 144 mg/kg dry weight, respectively . The fine-grained sediment spiked with picric acid generated a U-shaped concentration-response curve in the amphipod test, with increased survival both in the lowest and highest concentration . Grain-size distribution and organic carbon content strongly influenced the behavior of ordnance compounds in spiked sediments . Very low concentrations were measured in some of the treatments and irreversible binding and biodegradation are suggested as the processes responsible for the low measurements . Porewater toxicity varied with its sedimentary origin and with ordnance compound . The sea urchin embryological development test tended to be the least sensitive . Tetryl was the most toxic chemical in all porewater tests, and picric acid the least toxic . Samples spiked with 2,6-DNT contained a degradation product identified as 2-methyl-3-nitroaniline (also known as 2-amino-6-nitrotoluene), and unidentified peaks, possibly degradation products, were also seen in some of the picric acid- and tetryl-spiked samples . Degradation products may have played a role in observed toxicity.

Mar Pollut Bull, 2002 Aug, 44(8), 739 - 47
Biodegradation of petroleum hydrocarbons at low temperature in the presence of the dispersant Corexit 9500; Lindstrom JE et al.; Our study examined the effects of Corexit 9500 and sediment on microbial mineralization of specific aliphatic and aromatic hydrocarbons found in crude oil . We also measured gross mineralization of crude oil, dispersed crude oil and dispersant by a marine microbial consortium in the absence of sediment . When provided as carbon sources, our consortium mineralized Corexit 9500 the most rapidly, followed by fresh oil, and finally weathered oil or dispersed oil . However, mineralization in short term assays favored particular components of crude oil (2-methyl-naphthalene > dodecane > phenanthrene > hexadecane > pyrene) and was not affected by addition of nutrients or sediment (high sand, low organic carbon) . Adding dispersant inhibited hexadecane and phenanthrene mineralization but did not affect dodecane and 2-methyl-naphthalene mineralization . Thus, the effect of dispersant on biodegradation of a specific hydrocarbon was not predictable by class . The results were consistent for both high and low oiling experiments and for both fresh and weathered oil . Overall, our results indicate that environmental use of Corexit 9500 could result in either increases or decreases in the toxicity of residual oil through selective microbial mineralization of hydrocarbons.

Contracept Deliv Syst . 1984 Jul;5(3):15 p.
Different approaches in contraception; Runnebaum B et al.; PIP: Female contraception methods -- inhibiting ovulation (suppression of ovulation), inhibiting fertilization (fusion of the oocyte and the spermatozoa), inhibiting implantation (prevention of the nidation of the fertilized oocyte), and abortion pregnancy wastage); and male contraception methods -- spermatogenesis inhibition (disruption of spermatocyte formation) and methods acting on fertilization (fusion of sperm and oocyte) are reviewed . Ovulation can be inhibited by steroid hormones including synthetic estrogens and progestins and by releasing hormone analogs . Steroidal contraception is now used by approximately 60 million women worldwide . The objective in developing new contraceptives is to reduce the side effect rate . This might be possible by the detection of risk groups, the lowering of the steroid dose per cycle, and the introduction of new application schemes, the development of new steroids, and the improvement of steroid release . Oral contraceptives (OCs) should be applicable during lactation . This is possible by the development of substances which will not be transferred to the maternal milk or completely metabolized by the fetus . Due to the cardiovascular risks associated with both estrogens and progestins, the estrogen and progestin content of OCs has been reduced . Drugs with ovulatory inhibitory potency can be injected in the form of microcapsules or subcutaneously implanted or possibly applied as local plaster contraceptives . For implantables new technologies allow a slow release of substances from deposits by biodegradation of thecarriers . LHRH analogs (luteinizing hormone-releasing hormone) administered as nasal sprays, implantables, or injectables could not fulfill the hopes they had raised . The high rate of menstural cycle disturbances can only be prevented by progestins given in the 2nd part of the menstrual cycle . For the inhibition of fertilization of oocyte various different behavioral methods can prevent contact between oocyte and spermatozoa due to the time-dependent course of the menstrual cycle, e.g., symptothermal methods (e.g., Billings method, ovulation method) are gaining more acceptance . For immunological contraception both active and passive immunization can be applied . Implantation can be prevented by IUDs steroid hormones synthetic compounds, and immunological methods . For abortion, surgical methods, hormonal methods, plant extracts, and enzyme inhibitors can be used . In the male, spermatogenesis can be successfully inhibited by a large number of steroid hormones which lead to a fall of peripheral testicular levels . The solution of this problem would be to discover a substance which inhibits locally the testicular testosterone synthesis and would not influence peripheral androgen levels which are necessary for secondary sexual characteristics and the maintenance of libido . On the post testicular level, the ripening of the spermatozoa in the epididymis and sperm transport can be disturbed .

Chemosphere, 2002 Oct, 49(1), 61 - 73
An examination of the physical properties, fate, ecotoxicity and potential environmental risks for a series of propylene glycol ethers; Staples CA et al.; Propylene glycol ethers (PGEs) are comprised of mono-, di- and tri-PGEs and several of their acetate esters . The nature of the range of applications that use PGEs suggests that there is a potential for both intentional and unintentional entry of the materials into the environment . Selected physical/chemical properties, fate characteristics, aquatic toxicity data and calculated environmental concentrations were used to assess potential risks from the manufacture, handling, use, and disposal of PGEs . In general, the PGEs are low to moderately volatile, have high aqueous solubilities, low octanol-water partition coefficients (Kow), and bioconcentration factor values of <10, which indicate they are unlikely to accumulate in aquatic food chains . Both abiotic and biological degradation processes reduce environmental concentrations of PGEs . In air, vapor-phase PGEs react with photo-chemically produced hydroxyl radicals and have half-lives ranging from 5.5 to 34.4 h . A variety of ready and inherent biodegradation test methods, as well as tests that simulate biodegradation in wastewater treatment plants, surface water and soil have been conducted on PGEs . Significant aerobic biodegradation was generally observed, with a range of biodegradation half-lives on the order of 5-25 d . Acute aquatic toxicity studies with PGEs resulted in LC50 values ranging from approximately >100 to >20,000 mg/l for freshwater fish, the pelagic invertebrate Daphnia magna, green algae Selenastrum capricornutum (now called Pseudokirchneriella capricornutum) and bacteria . Level 3 multi-media modeling (EQC model of Mackay) was used to simulate regional-scale concentrations of PGEs in air, soil, water, and sediment . Toxicity thresholds were then compared with regional-scale water, soil and sediment concentrations to determine hazard quotients . Based upon this analysis, concentrations of PGEs are unlikely to pose adverse risks to the environment.

Environ Toxicol, 2002 Oct, 17(5), 457 - 61
Acute toxicity, mutagenicity, and estrogenicity of biodegradation products of bisphenol-A; Ike M et al.; Biodegradation of bisphenol-A (BPA), which is known as an estrogenic chemical, proceeds via complicated metabolic routes and leads to formation of several kinds of biodegradation products . Through the major route BPA can be completely mineralized; however, p-hydroxyacetophenone (p-HAP), p-hydroxybenzaldehyde (p-HBAL), and p-hydroxybenzoic acid (p-HBA) are transiently accumulated at relatively high concentrations . On the other hand, degradation of BPA through the minor route tends to cause the accumulation of 2,3-bis(4-hydroxyphenyl)-1,2-propanediol and p-hydroxyphenacyl alcohol as the dead-end products . To fully assess the impact of BPA discharge into the environment, the considerable BPA degradation products p-HAP, p-HBAL, and p-HBA and the mixture of the dead-end products were examined for their acute toxicity, mutagenicity, and estrogenicity using the Daphtoxkit (Creasel Ltd.), umu test system, and yeast two-hybrid system, respectively . BPA was moderately toxic to Daphnia magna (48-h EC(50) was 10 mg/L) and weakly estrogenic, with activity that was 5 orders of magnitude lower than that of 17beta-estradiol in the yeast screen, though no mutagenicity was observed . All the tested BPA biodegradation products showed very low acute toxicity compared with BPA, and none was mutagenic . A slight estrogenic activity was detected only for p-HAP among the tested degradation products . It was concluded that biodegradation can remarkably reduce the toxic effects of BPA .

Bioconjug Chem, 2002 Sep-Oct, 13(5), 952 - 7
Biodegradable, endosome disruptive, and cationic network-type polymer as a highly efficient and nontoxic gene delivery carrier; Lim YB et al.; The success of gene therapy is largely dependent on the delivery vector system . Efficient transfection and nontoxicity are two of the most important requirements of an ideal gene delivery vector . To generate both an efficient and nontoxic vector, we rationally constructed polymeric vectors to have simultaneous multiple functions, i.e., controlled degradation, an endosome disruptive function, and positive charges . Remarkably, the transfection efficiency of network poly(amino ester) (n-PAE) synthesized in this manner was comparable to that of polyethylenimine (PEI), one of the most efficient polymeric gene delivery vectors reported to date . However, there was a marked difference in cytotoxicity between the polymers . The majority of PEI-transfected cells were granulated and dead, whereas most of the cells transfected with n-PAE were viable and healthy . Successive events of efficient endosome escape of n-PAE/DNA polyplex and n-PAE biodegradation should result in high transfection efficiency and favorable cell viability response . The n-PAE-mediated transfection was also very efficient in the presence of serum . These data show that the approach we applied is a very appropriate way of making an ideal gene delivery carrier.

Res Microbiol, 2002 Jul-Aug, 153(6), 361 - 8
Relationship of chemical structures of textile dyes on the pre-adaptation medium and the potentialities of their biodegradation by Phanerochaete chrysosporium; Martins MA et al.; Azo dye derivatives of azobenzene constitute the largest group of dyes used in the textile industry and possess recalcitrant chemical groups, such as those of azo and sulphonic acid . Some microorganisms are able to degrade these aromatic compounds . In the present work, decolourisation of culture media containing azo dyes by the ligninolytic fungus Phanerochaete chrysosporium was achieved under nitrogen-limited conditions . The dyes used in the study are derivatives of meta- or para-aminosulphonic or aminobenzoic acids and include in their structures groups such as guaiacol or syringol, which are bioaccessible to the lignin degrading fungus P . chrysosporium . The aim of this study was to pre-adapt the microorganism to the structure of the dyes and to establish the relationships of the chemical structure of the dye present in the pre-adaptation medium with the chemical structure of the dye to be degraded . The azo dye used in the pre-adaptation medium that gave the best overall decolourisation performance was a meta-aminosulphonic acid and guaiacol derivative . The azo dye derivative of a meta-aminobenzoic acid and syringol showed a better performance in the decolourisation assays . Preliminary GC-MS studies indicated the formation of a nitroso substituted catechol metabolite, a precursor of aromatic ring cleavage, which was confirmed to occur by an enzymatic assay . The presence of this type of metabolite allows the establishment of a possible metabolic pathway towards mineralisation.

Plant Physiol, 1993 Mar, 101(3), 999 - 1004
Identification and Characterization of a Biodegradative Form of Threonine Dehydratase in Senescing Tomato (Lycopersicon esculentum) Leaf; Szamosi I et al.; Threonine dehydratase (TD; EC.4.2.1.16) is a key enzyme involved in the biosynthesis of isoleucine . Inhibition of TD by isoleucine regulates the flow of carbon to isoleucine . We have identified two different forms of TD in tomato (Lycopersicon esculentum) leaves . One form, present predominantly in younger leaves, is inhibited by isoleucine . The other form of TD, present primarily in older leaves, is insensitive to inhibition by isoleucine . Expression of the latter enzyme increases as the leaf ages and the highest enzyme activity is present in the old, chlorotic leaves . The specific activity of the enzyme present in older leaves is much higher than the one present in younger leaves . Both forms can use threonine and serine as substrates . Whereas TD from the older leaves had the same Km (0.25 mM) for both substrates, the enzyme from the young leaves preferred threonine (Km = 0.25 mM) over serine (Km = 1.7 mM) . The molecular masses of TD from the young and the old leaves were 370,000 and 200,000 D, respectively . High levels of the isoleucine-insensitive form of threonine dehydratase in the older leaves suggests an important role of threonine dehydratase in nitrogen remobilization in senescing leaves.

Water Res, 2002 Aug, 36(14), 3533 - 42
Passive dissolution of hydrogen gas into groundwater using hollow-fiber membranes; Fang Y et al.; A new hollow-fiber membrane remediation system has recently been developed to passively supply groundwater with dissolved hydrogen (H2) to stimulate the biodegradation of chlorinated solvents . Understanding the mass transfer behavior of membranes under conditions of creeping flow is critical for the design of such systems . Therefore, the objectives of this research were to evaluate the gas transfer behavior of hollow-fiber membranes under conditions typical of groundwater flow and to assess the effect of membrane configuration on gas transfer performance . Membrane gas transfer was evaluated using laboratory-scale glass columns operated at low flow velocities (8.6-12,973 cm/d) . H2 was supplied to the inside of the membrane fibers while water flowed on the outside and normal to the fibers (i.e . cross-flow) . Membrane configuration (single fiber and fabric) and membrane spacing for the fabric modules did not affect gas transfer performance . Therefore, the results from all of the experiments were combined to obtain the following dimensionless Sherwood number (Sh) correlation expressed as a function of Reynolds number (Re) and Schmidt number (Sc): Sh = 0.824Re(0.39)Sc(0.33) (0.0004<Re<0.6) . This correlation is useful for predicting the rate of transfer of any gas from clean membranes to flowing water at low Re . This correlation provides a basis for estimating the membrane surface area requirements for groundwater remediation as illustrated by a simple example.

Water Res, 2001 Nov, 35(16), 3791 - 800
Biodegradation of 1,4-dioxane in planted and unplanted soil: effect of bioaugmentation with Amycolata sp . CB1190; Kelley SL et al.; 1,4-Dioxane is one of the most recalcitrant and toxic contaminants in the subsurface . This study investigated the potential to enhance dioxane biodegradation in both planted and unplanted soil, by adding the dioxane-degrading actinomycete, Amycolata sp . CB1190 . Dioxane was not removed within 120 days in sterile controls or in viable microcosms not amended with CB 1190 . Poplar root extract (40 mg/L as COD) stimulated dioxane degradation in bioaugmented soil, and 100 mg/L dioxane were removed within 45 days . Other co-substrates that enhanced dioxane degradation by CB1190 include tetrahydrofuran (THF) and 1-butanol, while glucose and soil extract did not affect dioxane degradation . The stimulatory effect of THF was partly due to enhanced enzyme induction, while that of root extract and 1-butanol was attributed to additional growth of CB1190 . In another experiment with dioxane added at 10 mg/kg-soil . reactors planted with hybrid poplar trees removed (by evapotranspiration and biodegradation in the root zone) more dioxane within 26 days than unplanted reactors, regardless of whether CB1190 was added . Nevertheless, CB1190 enhanced mineralization of {14C}-dioxane in all experiments . This enhancement was more pronounced in unplanted soil because plant uptake reduced the availability of dioxane for microbial degradation . These results suggest that bioaugmented phytoremediation is an attractive alternative to remove dioxane from shallow contaminated sites.

Sheng Wu Yi Xue Gong Cheng Xue Za Zhi, 2002 Jun, 19(2), 315 - 9
{The advance of research for biocompatibility of medical polyurethanes}; Li J et al.; Polyurethanes are popularly used in cardiovascular and other biomedical fields due to their good biocompatibility as well as mechanical properties . But they are subject to biodegradation in vivo for a long time, and cause inflammation, so improving the biocompatibility of medical polyurethanes is an important subject of biomaterials . Recent researches have focused on biological modelling of biomaterials for improving the biocompatibility of polyurethanes . This paper reviews two main methods for improving biocompatibility of polyurethanes-endothelial cells seeding and mimic biomembrane (phospholipid surface), and summarizes the main procedures and questions of these two methods.

Ying Yong Sheng Tai Xue Bao, 2002 Apr, 13(4), 501 - 4
{Behaviors of polycylic aromatic hydrocarbons (PAHs) in the soil}; Gao X et al.; Adsorption equilibrium of PAHs in the soil can be reached by two mainly processes, "quick" and "slow" . Although PAHs with low molecular may be absorbed by the plant root, and transferred and transformed into other upper part of plant, the main accumulation pathway for PAHs in plant is from the air to the leaf surface . Microbial degradation of PAHs by its enzymatic capacity is the main process of the degradation of PAHs in nature . In addition, factors effecting the biodegradation of PAHs are analyzed in details in this review.

Environ Microbiol, 2002 Sep, 4(9), 532 - 7
Metabolic biomarkers for monitoring anaerobic naphthalene biodegradation in situ; Phelps CD et al.; During the anaerobic biodegradation of naphthalene and methylnaphthalene, unique metabolites are formed by specific microbial carboxylation and ring-reduction reactions . Groundwater samples from an anoxic, shallow aquifer contaminated with gasoline were examined for the presence of these metabolites by extraction, derivatization and gas chromatography coupled to mass spectroscopy . Several metabolites {2-naphthoic acid (2-NA), tetrahydro-2-naphthoic acid (TH-2-NA), hexahydro-2-naphthoic acid (HH-2-NA) and methylnaphthoic acid (MNA)} were found to be present in the groundwater samples . The concentration of 2-NA at each monitoring well was quantified and correlated to the zones of contamination . The presence of the other metabolites in the same wells as 2-NA was used as confirmation that the anaerobic pathway was indeed active . The distribution of metabolites at this site shows that they can be used as biomarkers for demonstrating in situ biodegradation.

Environ Toxicol Chem, 2002 Sep, 21(9), 1757 - 65
Aerobic biodegradation of aliphatic polyethoxylates: an 1H-nuclear magnetic resonance spectroscopy investigation; de Lazzari A et al.; Aerobic biodegradation tests of three blends representative of the most commonly marketed aliphatic alcohol polyethoxylates (AE) and a commercial polyethylene glycols (PEG) mixture were run under standard test conditions (Organization for Economic Cooperation and Development, Paris, France {OECD} 301 E protocol) . The test liquors were investigated using a 400-MHz proton-nuclear magnetic resonance (1H-NMR) spectrometer in order to elucidate the biodegradation mechanism . Diagnostic signals for both linear and branched AE homologs were identified by bidimensional homocorrelated spectroscopy (COSY) and by double quantum filter correlated spectroscopy (DQFCOSY) . The 1H-NMR allowed individually monitoring the fate of the alkyl and polyethoxyl fragments of the parent compounds and distinguishing between oxidative and nonoxidative polyethoxyl depolymerization, which could not be performed by other reported techniques such as high-peformance liquid chromatography (HPLC) or mass spectrometry (MS) or FAB spectroscopy . The AE biodegradation time profiles showed that under the test conditions, both alkyl and polyethoxyl chains of the linear and oxo-AE were biodegraded quite readily . The removal of the multibranched AE was slower when compared to that of linear and oxo-AE, while PEG exhibited a time profile characterized by a biodegradation rate significantly slower than that of PEG released by the microbial attack of linear and oxo-AE . In the case of linear AE, the alkyl chain was biodegraded much faster than the polyethoxyl chain, while in the case of oxo- and multibranched AE, both the alkyl and the polyethoxyl chains were biodegraded at similar rates.

Mar Environ Res, 2002 Aug, 54(2), 157 - 68
Bacterioplanktonic abundance, productivity and petroleum hydrocarbon biodegradation in marinas and other coastal waters in North Carolina, USA; Piehler MF et al.; The purpose of this study was to assess the differences in the abundance and activity of the bacterioplankton at sites with varied boating activity, and to determine the response of the communities to additional petroleum pollution . Three sites, including two marinas and a site on Bogue Sound in coastal North Carolina, were selected for monthly experiments . Seasonal patterns of bacterioplanktonic abundance and diesel fuel biodegradation for each site were examined, and possible correlations with intensity of boating activities were explored . Bacterioplanktonic communities at the three sites in this study were more similar in their structure and biodegradation potential than would have been expected from previous studies . We found no differences in the abundance and biodegradation potential of theses communities at the three sites, and only a slightly elevated number of hydrocarbon degraders at one of the marinas . Patterns of biodegradation were more closely related to total bacterial abundance, rather than number of petroleum hydrocarbon degraders . There was a strong seasonal pattern in bacterial abundance and biodegradation at all three sites . The bacterioplanktonic Community at all sites responded similarly to additions of diesel fuel . Bacterial abundance and productivity were both elevated to some extent, and number of petroleum hydrocarbon degraders changed relatively little . These data indicate that marinas may not profoundly after the bacterioplankton and that coastal waters often have resident bacterial communities capable of degrading petroleum hydrocarbon pollution.

Water Sci Technol, 2002, 46(1-2), 565 - 9
Anaerobic sequencing batch reactor as initiating stage in complete pentachlorophenol biodegradation; Ribarova I et al.; Biodegradation of pentachlorophenol (PCP) has been studied in a sequence of two completely mixed reactors . Investigation on the first anaerobic sequencing batch reactor (AnSBR) is discussed in detail in this paper . Key technological and microbiological features were studied: two different types of adaptation process of anaerobic sludge towards PCP detoxication; the influence of the sludge concentration upon the rate of PCP biodegradation; minimum retention time for PCP degradation in dependence on the PCP concentration; modeling of the PCP degradation process; effluent COD and SS concentrations; changes in the micro- and macrostructure of the sludge during acclimatization process.

Microbiology, 2002 Sep, 148(Pt 9), 2883 - 8
Assimilatory detoxification of herbicides by Delftia acidovorans MC1: induction of two chlorocatechol 1,2-dioxygenases as a response to chemostress; Benndorf D et al.; Proteome analysis of bacteria that can detoxify harmful organic compounds enables the discovery of enzymes involved in the biodegradation of these substances and proteins that protect the cell against poisoning . Exposure of Delftia acidovorans MC1 to 2,4-dichlorophenoxypropionic acid and its metabolites 2,4-dichlorophenol and 3,5-dichlorocatechol during growth on pyruvate as a source of carbon and energy induced several proteins . Contrary to the general hypothesis that lipophilic or reactive compounds induce heat shock or oxidative stress proteins, no induction of the GroEL, DnaK and AhpC proteins that were used as markers for the induction of heat shock and oxidative stress responses was observed . However, two chlorocatechol1,2-dioxygenases, identified by amino terminal sequence analysis, were induced . Both enzymes catalyse the conversion of 3,5-dichlorocatechol to 2,4-dichloro-cis,cis-muconate indicating that biodegradation is a major mechanism of resistance in the detoxifying bacterium D . acidovorans MC1.

Biotechnol Bioeng, 2002 Oct 5, 80(1), 100 - 13
Yield prediction and stoichiometry of multi-step biodegradation reactions involving oxygenation; Yuan Z et al.; Microorganisms can initiate the degradation of organic compounds by oxygenation reactions that require the investment of energy and electrons . This diversion of energy and electrons away from synthesis reactions leads to decreased overall cell yields . A thermodynamic method was developed that improves the accuracy of cell yield prediction for compounds degraded through pathways involving oxygenation reactions . This method predicts yields and stoichiometry for each step in the biodegradation pathway, thus enabling modeling a multi-step biodegradation process in which oxygenations occur and intermediates may persist . EDTA and benzene biodegradation are presented as examples . The method compares favorably with other yield prediction methods while providing additional information of yields for intermediates produced in the degradation pathway .

J Agric Food Chem, 2002 Sep 11, 50(19), 5373 - 7
Behavior of metalaxyl and its pure R-enantiomer in sunflower plants (Helianthus annus); Zadra C et al.; A possible stereospecific and/or stereoselective mechanism of biodegradation for metalaxyl and metalaxyl-M was studied to elucidate their behavior in sunflower plants and to compare their biodegradation . Greenhouse experiments were carried out to confirm the same efficacy of the two fungicides against infections by Plasmopara helianthi in sunflower plants . The two fungicides appear to have the same behavior regarding both the protection against plant infections and the mode of translocation and the rate and pathway of biotransformation, but we have evidence that this biotransformation process is enantioselective . Furthermore, we propose procedures for a chromatographic separation of enantiomers and acid metabolites of the fungicides and for the determination of the R:S ratio by HPLC chiral analyses . This study emphasizes the importance of examining the fate of both stereoisomers of a chiral agrochemical in an environmental system for the correct use of enantiomerically pure agrochemical compounds.

Biomol Eng, 2002 Aug, 19(2-6), 295 - 8
Biodegradable polymer networks based on oligolactide macromers: synthesis, properties and biomedical applications; Schnabelrauch M et al.; Novel linear and star-shaped oligolactide macromers were synthesized by ring-opening oligomerization of L-lactide in the presence of suitable initiators (di- and polyols, amino acid esters) and subsequent endgroup-functionalization of the formed oligolactides with methacrylate moities . The obtained liquid macromers are valuable building blocks for the preparation of biocompatible polymer networks . Based on these macromers, the fabrication and the material properties including biodegradation behaviour of highly porous polymer network devices will be described . The application of these materials as resorbable scaffolds in tissue engineering will be discussed.

Tissue Eng, 2002 Aug, 8(4), 649 - 59
Tissue compatibility of two biodegradable tubular scaffolds implanted adjacent to skin or buccal mucosa in mice; Aframian DJ et al.; Radiation therapy for cancer in the head and neck region leads to a marked loss of salivary gland parenchyma, resulting in a severe reduction of salivary secretions . Currently, there is no satisfactory treatment for these patients . To address this problem, we are using both tissue engineering and gene transfer principles to develop an orally implantable, artificial fluid-secreting device . In the present study, we examined the tissue compatibility of two biodegradable substrata potentially useful in fabricating such a device . We implanted in Balb/c mice tubular scaffolds of poly-L-lactic acid (PLLA), poly-glycolic acid coated with PLLA (PGA/PLLA), or nothing (sham-operated controls) either beneath the skin on the back, a site widely used in earlier toxicity and biocompatibility studies, or adjacent to the buccal mucosa, a site quite different functionally and immunologically . At 1, 3, 7, 14, and 28 days postimplantation, implant sites were examined histologically, and systemic responses were assessed by conventional clinical chemistry and hematology analyses . Inflammatory responses in the connective tissue were similar regardless of site or type of polymer implant used . However, inflammatory reactions were shorter and without epithelioid and giant cells in sham-operated controls . Also, biodegradation proceeded more slowly with the PLLA tubules than with the PGA/PLLA tubules . No significant changes in clinical chemistry and hematology were seen due to the implantation of tubular scaffolds . These results indicate that the tissue responses to PLLA and PGA/PLLA scaffolds are generally similar in areas subjacent to skin in the back and oral cavity . However, these studies also identified several potentially significant concerns that must be addressed prior to initiating any clinical applications of this device.

Appl Environ Microbiol, 2002 Sep, 68(9), 4672 - 5
Enzymatic degradation of chlorodiamino-s-triazine; Seffernick JL et al.; 2-Chloro-4,6-diamino-s-triazine (CAAT) is a metabolite of atrazine biodegradation in soils . Atrazine chlorohydrolase (AtzA) catalyzes the dechlorination of atrazine but is unreactive with CAAT . In this study, melamine deaminase (TriA), which is 98% identical to AtzA, catalyzed deamination of CAAT to produce 2-chloro-4-amino-6-hydroxy-s-triazine (CAOT) . CAOT underwent dechlorination via hydroxyatrazine ethylaminohydrolase (AtzB) to yield ammelide . This represents a newly discovered dechlorination reaction for AtzB . Ammelide was subsequently hydrolyzed by N-isopropylammelide isopropylaminohydrolase to produce cyanuric acid, a compound metabolized by a variety of soil bacteria.

Biomaterials, 2002 Nov, 23(21), 4167 - 76
Bone repair in radii and tibias of rabbits with phosphorylated chitosan reinforced calcium phosphate cements; Wang X et al.; Biocompatibility of two calcium phosphate cements (CPCs), reinforced with phosphorylated chitosan (P-chitosan), was investigated in rabbits in present study . The two CPCs are monocalcium phosphate monohydrate (MPCM) with calcium oxide (CaO) in 1 M phosphate buffer (i.e . MCPM/CaO/1 M phosphate buffer cement, CPC-I) and dicalcium phosphate dihydrate (DCPD) with calcium hydroxide {Ca(OH)2} in 1 M Na2HPO4 solution (i.e . DCPD/Ca(OH)2/1 M Na2HPO4 cement, CPC-II) . Different amount of P-chitosan was added to the liquid phase before the power phase was mixed with the liquid phase . The MCPM/CaO/1 M phosphate buffer/P-chitosan cements (P-CPC-I) with neutral pH were filled into the holey defects of rabbit tibias . While the DCPD/Ca(OH)2/1 M Na2HPO4/P-chitosan cements (P-CPC-II) shaped as prehardened cylinders were implanted into rabbit radial defects . After operation, the two serial groups and CPC-II controls were observed for 1, 4, 12 and 22 weeks, respectively . Histological and histomorphological studies proved that P-chitosan containing cements are biocompatible, bioabsorbable and osteoinductive . The biodegradation rate has a negative relationship with the P-chitosan content . Progressive substitution took place at the interface of implants and host bones . No adverse effects were found in tissues around the bone defects . Thus, they could be used as bone substitutes in clinic.

Arch Microbiol, 2002 Sep, 178(3), 208 - 17 Epub 2002 Jun 21.
Characterization of four olive-mill-wastewater indigenous bacterial strains capable of aerobically degrading hydroxylated and methoxylated monocyclic aromatic compounds; Di Gioia D et al.; Seven aerobic bacterial strains capable of degrading several of the monocyclic aromatic compounds occurring in the phenolic fraction of olive-mill wastewaters (OMWs) were isolated from an Italian OMW . The results of the 16S rDNA restriction analysis evidenced that these strains are distributed among four different groups . One strain of each group was taxonomically characterized by sequencing the amplified 16S rDNA, and the four strains were assigned to the genera Comamonas (strain AV1A), Ralstonia (strain AV5BG), Pseudomonas (strain AV2A) and Sphingomonas (strain AV6C) . The four strains, when checked for the ability to degrade nine monocyclic aromatic compounds abundant in OMWs, were found to significantly metabolize five to eight of them, both as resting cells and growing cells . Specific enzyme analyses of the same selected strains showed: (1) the occurrence of O-demethylating activities towards four methoxylated mono-aromatic acids in three of the four studied strains (strains AV1A, AV5BG and AV6C), (2) ring-cleavage activity towards protocatechuic acid in all of the strains, and (3) a ring-cleavage activity towards catechol in strain AV6C . The isolates described here exhibit a biodegradation potential towards monocyclic aromatic compounds of OMWs that is markedly broader and higher than that displayed by other aerobic bacteria described previously . These features make them excellent candidates for removing the low-molecular-weight phenolic compounds persisting in the effluent following anaerobic digestion of OMWs.

J Agric Food Chem, 2002 Aug 28, 50(18), 5070 - 6
Temperature and pH effects on biodegradation of hexachlorocyclohexane isomers in water and a soil slurry; Siddique T et al.; This study was conducted to monitor the biodegradation of alpha-, beta-, gamma-, and delta-hexachlorocyclohexane (HCH) isomers in liquid culture by a Pandoraea species and determine the influence of pH and temperature on the biodegradation of alpha- and gamma-HCH in liquid as well as in soil slurry cultures . The Pandoraea species degraded 79.4% delta-HCH and 34.3% gamma-HCH in liquid culture at 4 weeks of incubation . alpha- and beta-HCH exhibited almost identical rates (41.6 and 42.4%, respectively) of degradation . The highest degradation of alpha- and gamma-HCH (67.1 and 60.2%, respectively) was observed at an initial pH of 8.0 in liquid; 58.4 and 51.7% rates of degradation of alpha- and gamma-HCH, respectively, at an initial pH of 9.0 were found in soil slurry cultures . An incubation temperature of 30 degrees C was optimum for effective degradation of alpha- and gamma-HCH isomers (62.5 and 57.7%, respectively) in liquid culture, and 54.3 and 51.9% rates of degradation of alpha- and gamma-HCH isomers, respectively, were found in a soil slurry . Increasing the soil/water ratio decreased the extent of degradation of both HCH isomers . Degradation of HCH isomers occurred concomitant with bacterial growth . Byproducts of growth from Pandoraea species significantly decreased the pH of the liquid and the soil slurry during the growth on HCH isomers . The results of this study suggest that this bacterial strain may effectively be used for remediating polluted sites and water contaminated with different HCH isomers over a range of environmental conditions.

Environ Sci Technol, 2002 Aug 1, 36(15), 3284 - 9
Leaching and primary biodegradation of sulfonated naphthalenes and their formaldehyde condensates from concrete superplasticizers in groundwater affected by tunnel construction; Ruckstuhl S et al.; Sulfonated naphthalenes and their formaldehyde condensates (SNFC) are used as concrete superplasticizers fortunnel construction through aquifers.This paperdiscusses their primary biodegradation in groundwater affected by construction activities . The analyses of groundwater samples collected 5 m away from a construction site clearly indicated that components of the applied SNFC product leached into the groundwater . A maximum total concentration of these compounds of 233 microg/L was found, and it was shown that only the monomeric sulfonated naphthalenes andthe condensates uptothetetramerleached in substantial amounts . The decrease in concentration of several monomeric components could not be explained by mere dispersion but rather indicates a biological transformation in the aquifer . This was confirmed at a second field site and by laboratory degradation experiments with piezometer material as inoculum . Lag phases for the individually degradable sulfonated naphthalenes ranged from 0 to 96 d . Naphthalene-1,5-disulfonate and the oligomeric components were neither degraded in the aquifer nor in the laboratory experiments within an observation time of up to 195 d . This clearly indicates their persistence in subsurface waters.

SAR QSAR Environ Res, 2002 May-Jun, 13(3-4), 445 - 55
Quantitative prediction of biodegradability, metabolite distribution and toxicity of stable metabolites; Dimitrov S et al.; An evaluation of the capability of organic chemicals to mineralize is an important factor to consider when assessing their fate in the environment . Microbial degradation can convert a toxic chemical into an innocuous one, and vice versa, or alter the toxicity of a chemical . Moreover, primary biodegradation can convert chemicals into stable products that can be difficult to mineralize . In this paper, we present some new results obtained on the basis of a recently developed probabilistic approach to modeling biodegradation based on microbial transformation pathways . The metabolic transformations and their hierarchy were calibrated by making use of the ready biodegradability data from the MITI-I test and expert knowledge for the most probable transformation pathways . A model was developed and integrated into an expert software system named CATABOL that is able to predict the probability of biodegradation of organic chemicals directly from their structure . CATABOL simulates the effects of microbial enzyme systems, generates the most plausible transformation pathways, and quantitatively predicts the persistence and toxicity of the biodegradation products . A subset of 300 organic chemicals were selected from Canada's Domestic Substances List and subjected to CATABOL to compare predicted properties of the parent chemicals with their respective first stable metabolite . The results show that most of the stable metabolites have a lower acute toxicity to fish and a lower bioaccumulation potential compared to the parent chemicals . In contrast, the metabolites appear to be generally more estrogenic than the parent chemicals.

J Biomater Sci Polym Ed, 2002, 13(6), 691 - 711
Identification of biodegradation products formed by L-phenylalanine based segmented polyurethaneureas; Elliott SL et al.; The degradation of novel biodegradable segmented polyurethanes was investigated with a view to determining the cleavage points within the polymer backbones targeted by the enzyme chymotrypsin . While the materials were developed with specific enzyme cleavage sites designed into the polymer chains, the nature of their degradation had not yet been determined . In this work, two segmented polyurethaneureas containing L-phenylalanine residues in the chain extender and two control polymers were subjected to degradation in the presence of chymotrypsin . Samples were collected for analysis over a time period from 1 day to 8 weeks . The degradation products from these materials were isolated using solid phase extraction and reversed phase high pressure liquid chromatography, and identified using mass and tandem mass spectrometry . Three hard segment related degradation products were identified and provide important insight into the polyurethane backbone cleavage sites . Cleavage of urea, ester and urethane bonds were observed . The results confirmed that chymotrypsin was able to cleave ester bonds adjacent to phenylalanine residues contained within the novel chain extender.

J Biomater Sci Polym Ed, 2002, 13(6), 651 - 65
The effect of oxidation on the enzyme-catalyzed hydrolytic biodegradation of poly(urethane)s; Labow RS et al.; Although the biodegradation of polyurethanes (PU) by oxidative and hydrolytic agents has been studied extensively, few investigations have reported on the combination of their effects . Since neutrophils (PMN) arrive at an implanted device first and release HOCl, followed by monocyte-derived macrophages (MDM) which have potent esterase activities and oxidants of their own, the combined effect of oxidative and hydrolytic degradation on radiolabeled polycarbonate-polyurethanes (PCNU)s was investigated and compared to that of a polyester-PU (PESU) and a polyether-PU (PEU) . The PCNUs were synthesized with PCN (MW = 1,000), and butanediol (14C-BD) and one of two diisocyanates, hexane-1,6-diisocyanate (14C-HDI) or methylene bis-p-phenyl diisocyanate (MDI) . The PESU and PEU were synthesized using toluene-diisocyanate (14C-TDI), with polycaprolactone and polytetramethylene oxide as soft segments respectively, and ethylene diamine as the chain extender . The effect of pre-treatment with 0.1 mM HOC1 for 1 week on the HDI-based PCNUs and both TDI-based PUs resulted in a significant inhibition of radiolabel release (RR) elicited by cholesterol esterase (CE), when compared to buffer alone, whereas the MDI-based PCNU showed a small but significant increase . When PMN were activated on the HDI-based PCNU surface with phorbol myristate acetate (PMA), HOCl was released for 3 h, and was almost completely abolished by sodium azide (AZ) . Simultaneously, the PMN-elicited RR, shown previously to be due to the esterolytic cleavage by serine proteases, was inhibited approximately 75% by PMA-activation of the cells, but significantly increased relative to the latter when AZ was added . Both in vitro oxidation by HOCl and the release of HOCI by PMN were associated with the inhibition of RR and suggest perturbations between oxidative and hydrolytic mechanisms of biodegradation.

Int J Oral Maxillofac Implants, 2002 Jul-Aug, 17(4), 581 - 6
Bone response to plasma-sprayed hydroxyapatite and radiofrequency-sputtered calcium phosphate implants in vivo; Ong JL et al.; PURPOSE: The objective of this study was to evaluate the effect of radiofrequency- (RF) sputtered calcium phosphate (CaP) coating of titanium implants on bond strength at the bone-implant interface and percent bone contact length . MATERIALS AND METHODS: Cylindric sputtered CaP-coated and plasma-sprayed hydroxyapatite- (HA) coated implants (4.0 mm diameter and 8 mm length) were implanted in dog mandibles . Half the sputtered CaP-coated implants were heat-treated . RESULTS: Twelve weeks after implant placement, no statistical differences in the mean ultimate interfacial strengths were observed between as-sputtered CaP-coated, sputtered CaP-coated heat-treated, and control plasma-sprayed HA-coated implants . Histomorphometric evaluation indicated that the percent bone contact lengths for the plasma-sprayed HA-coated implants and the as-sputtered CaP-coated implants were similar and significantly greater than that for the sputtered CaP-coated heat-treated implants . Differences in the ultimate interfacial strength and percent bone contact length between different implant sites in the mandible were not observed . DISCUSSION: The results of this study, considered together with the results of previous studies, suggest that once early osseointegration is achieved, biodegradation of the thin CaP coatings is not detrimental to bone-coating-implant fixation, and does not compromise bone responses to the coated implant surfaces . CONCLUSION: The interfacial strength and histomorphometric data suggest that the CaP coatings applied using the sputtering process produce bone responses similar to those of HA coatings applied using plasma spraying.

Int Microbiol, 2002 Jun, 5(2), 53 - 63
Biodegradation and biological treatments of cellulose, hemicellulose and lignin: an overview; Perez J et al.; In nature, cellulose, lignocellulose and lignin are major sources of plant biomass; therefore, their recycling is indispensable for the carbon cycle . Each polymer is degraded by a variety of microorganisms which produce a battery of enzymes that work synergically . In the near future, processes that use lignocellulolytic enzymes or are based on microorganisms could lead to new, environmentally friendly technologies . This study reviews recent advances in the various biological treatments that can turn these three lignicellulose biopolymers into alternative fuels . In addition, biotechnological innovations based on natural delignification and applied to pulp and paper manufacture are also outlined.

Rev Argent Microbiol, 2002 Apr-Jun, 34(2), 72 - 6
Use of a CO2 electrode to monitor fermentations that use xenobiotic compounds as source of carbon; Englebienne P et al.; Bacterial strains were isolated from contaminated waters, mud or soils . They are capable of growing in mineral medium with different chemicals as carbon source, such as aliphatic or aromatic hydrocarbons and polychlorinated biphenyls (PCBs) . Most of these strains tolerate high concentrations (up to 30% v/v) of the xenobiotic substrates . This is particularly important for the development of fermenting processes to treat effluents or residues with a high content of contaminating compounds . An ion-specific potentiometric electrode (CO2) has been developed to measure CO2 production continuously . When the different strains were incubated in a mineral medium and in the presence of the corresponding substrate, a parallel between growth, substrate consumption and CO2 production was found . The developed system is suggested as an efficient and economical alternative to evaluate the potential of biodegradation by different microorganisms.

Res Front Fertil Regul, 1984 Dec, 3(2), 1 - 10
Long-acting injectable norethisterone contraceptive system: review of clinical studies; Beck LR et al.; PIP: This report summarizes research supported by the Program for Applied Research on Fertility Regulation (PARFR) to develop a long-acting, injectable, biodegradable miscrosphere delivery system for norethisterone (NET) . This delivery system consists of microspheres composed of a biodegradable polymer and NET . The polymer 1st evaluated for making NET microspheres was dl-polylactic acid (PLA) . This prototype system was tested in clinical trials involving 63 women at 3 centers . The results of these studies indicated that PLA microspheres are capable of delivering NET continously for about 6 months . The duration of ovarian suppression was dose dependent with a given microsphere formulation and size limit . The average number of bleeding and spotting days decreased with increasing time from injection . Up to 12 months was required for the PLA microspheres to completely degrade, however, and there was concern that repeated injections at 6-month intervals might allow an undesirable build-up of PLA in muscle tissues . Research efforts then centered on developing a polymer formulation that offered better synchronization between duration of NET release and biodegradation of the polymer . In the 2nd generation formulation, polyglycolic acid (PGA) was incorporated to achieve faster biodegradation . Phase II studies were based on a formulation that demonstrated improvements in the manufacturing process, pharmacokinetics of the NET microspheres, biodegradation kinetics of the polymer, and injectability . More precise control of release has been obtained, the drug loading and size distribution of the microspheres have been optimized, and the molar ratios of PLA and PGA have been changed . Although Phase II studies are still in progress, higher NET-loaded microspheres have been shown to product substantially faster release rates during the 1st 30 days post-treatment . In addition, increasing the NET concentration to 50% substantially improved formulation injectability . Few obstacles to eventual approval and widescale use of this injectable contraceptive system are anticipated . Studies are currently underway to provide better bleeding control .

Int J Pharm, 2002 Aug 21, 242(1-2), 247 - 9
Biodegradation and drug release studies of BSA loaded gelatin microspheres; Mladenovska K et al.; Certain variations in the process parameters (emulsification time, surfactant concentration) were performed in order to prepare BSA-loaded gelatin microspheres with high loading efficacy and particle size ranging from 1 to 10 microm using a procedure originally employed by Tabata and Ikada . The mathematical modelling of drug release in the presence of collagenase showed a biphasic release pattern, where the rate constant for the initial time release confirmed the influence of the particle size and/or enzymatic degradation rate on drug release rate.

Appl Microbiol Biotechnol, 2002 Aug, 59(4-5), 591 - 8 Epub 2002 Jun 08.
The influence of lignin content and temperature on the biodegradation of lignocellulose in composting conditions; Vikman M et al.; The aim of this research was to study the influence of lignin content and composting temperature on the biodegradation of lignin-containing pulp and paper products in a controlled composting test (European standard prEN 14046) . Lignin reduced the biodegradation of the samples, and there was a linear correlation between the lignin content and the biodegradation of pulp and paper products at 58 degrees C . The influence of incubation temperature (35, 50 and 58 degrees C) on biodegradation was studied using bleached kraft paper containing 0.2 wt% lignin and mechanical pulp (stone-ground wood) containing 24-27 wt% lignin . Mechanical pulp biodegraded better at lower temperatures, while kraft paper biodegraded well at all three temperatures . Microbial activity was evaluated by measuring CO(2) evolution and the change in ATP content, and fungal biomass by measuring the ergosterol content during the composting experiments . Kraft paper strongly increased microbial activity during the controlled composting test, but the activity returned to the background level at the end of the composting test . The proportion of sample carbon converted to microbial biomass carbon was considerably higher at lower incubation temperatures . Changes in microbial community structure during biodegradation of mechanical pulp and kraft paper at 50 degrees C were studied by the PCR-based technique denaturing gradient gel electrophoresis . Changes in the microbial community were observed during the intensive degradation phase of kraft paper.

Biomaterials, 2002 Oct, 23(19), 3969 - 75
Human macrophage-mediated biodegradation of polyurethanes: assessment of candidate enzyme activities; Labow RS et al.; A predominant cell type associated with explanted failed devices is the monocyte-derived macrophage (MDM) . However, there is still very little known about the specific cellular enzyme activities involved in interactions with these devices . The current study investigates the nature of candidate enzymes that may be involved in the degradation of polymeric biomaterials through the use of specific enzyme inhibitor agents . When MDM were incubated with a polycarbonate-based polyurethane (PCNU) synthesized with 14C-labeled hexane diisocyanate (HDI), polycarbonate diol and butanediol (BD) (referred to as 14C-HDI431), the radiolabel release (RR) measured was inhibited by phenylmethylsulfonyl fluoride, diethyl-p-nitrophenyl phosphate (serine protease/esterase inhibitors), and sodium fluoride (NaF) (a carboxyl esterase (CXE) inhibitor) . Sodium taurocholate (NaT) (a cholesterol esterase (CE) stimulator) had little effect on RR . The two candidate enzymes proposed were CE and CXE, based on the fact that both were identified by immunoblotting in the releasate of MDM following 48 h incubation with 14C-HDI431 . The effect of the above reagents on the RR caused by purified CE and CXE, was measured and compared to changes in their activity with p-nitrophenylbutyrate (PNB) . The effect of NaF on MDM was similar to that of purified CXE (inhibitory on both RR and lysate esterase activity), suggesting the involvement of CXE . However, NaT inhibited the PNB activity of purified CXE, but had no effect on MDM-mediated RR or PNB activity, implicating another esterase in the biomaterial degradation . Since NaT stimulated CE-mediated RR and PNB activity, it may also be involved in MDM-mediated biodegradation of PCNUs . The results of these studies point to both esterases as being candidates . However, the current methods were unable to determine the relative contribution of each one to the observed biodegradation.

J Biomater Sci Polym Ed, 2002, 13(4), 463 - 83
Influence of surface morphology and chemistry on the enzyme catalyzed biodegradation of polycarbonate-urethanes; Tang YW et al.; Polycarbonate based polyurethanes were synthesized with varying hard segment content as well as hard segment chemistry based on three different diisocyanates,1,6-hexane diisocyanate (HDI), 4.4'-methylene bisphenyl diisocyanate (MDI) and 4,4-methylene biscyclohexyl diisocyanate (HMDI) . The surface chemistry and morphology were characterized using X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) . The polymers were incubated with cholesterol esterase (CE) in a phosphate buffer solution at 37 degrees C over 10 weeks . XPS results showed that the surface chemistry changed as the size and chemistry of the hard segment varied within the materials . AFM images exhibited distinctive surface morphologies for all polymers, and this was particularly apparent with changes in the hard segment chemistry . The results showed that the surface of HDI polymers consisted of relatively stiff rod-like structures, which corresponded to the soft segment domains . Polymers with a higher HDI content exhibited a dense top layer containing a relatively higher hard segment component, covering the sub-surface matrix of rod like structures . The MDI based polyurethane had large aggregates on its top surface, which corresponded to the aggregation of harder components . The HMDI based polycarbonate-urethane presented a relatively homogeneous surface where no phase separation could be detected . The relative differences in hard and soft segment content in their surface structure was supported by XPS findings . The analysis of the biodegradation results, concluded that enzyme catalyzed biodegradation within these materials was initiated in amorphous soft segment regions located in the region of the interface between hard and soft segments . A higher hard segment content at the surface contributed significantly to an increase in biostability . The findings provided an enhanced understanding for the role of surface molecular structure in the enzyme catalyzed biodegradation of polyurethanes.

Biotechnol Prog, 2002 Jul-Aug, 18(4), 728 - 33
Mass transfer and hydrocarbon biodegradation of aged soil in slurry phase; Garcia-Rivero M et al.; Addition of toluene into slurry phase laboratory microcosm is proposed in order to increase desorption rate of hydrocarbons and as an alternative to improve bioavailability of hydrocarbon in aged soils . Our studies showed that toluene has a positive effect on desorption of total petroleum hydrocarbons (TPH) . Addition of 14,000 mg toluene/kg of soil, in highly polluted soil, increased the consumption rate of hydrocarbons three times in comparison to control without solvent . In 30 days the initial TPH concentration in soil, 292,000 mg/kg, diminished 45% . Although toluene was able to dissolve complex organic compounds such as asphaltene fraction, it probably yielded a highly toxic toluene-hydrocarbons phase . The inhibitory effect of toluene-TPH was also studied . A substrate inhibition model was used: the k(m) and k(i) constants were 57 and 490 mg TPH/L liquid phase, respectively . Experimental data were well described when the proposed model included sequential desorption and biodegradation phenomena . Damkohler number evaluation showed that rate of mass transfer was the limiting step in overall biodegradation in nonsolvent control . When high concentration of toluene was added, then bioreaction was the limiting step, but inhibitory effect should be considered . However, toluene addition at low concentrations facilitates the biodegradation of aromatic compounds.

Waste Manag Res, 2002 Jun, 20(3), 234 - 42
Material and energy balances in a large-scale aerobic bioconversion cell; Themelis NJ et al.; On the basis of earlier experimental studies of the aerobic bioconversion of organic wastes, the preferred values of operating parameters and the biochemical rate constants of oxidation to CO2 and H2O were identified . Energy and material balances were then constructed for a large, 3 m deep aerobic cell holding 1,440 tons of the 'wet' component of organic wastes (major organic constituent: {C6H10O4}n) . It was found that conduction/convection and radiation losses to the surroundings amount to a relatively small fraction of the chemical heat released by oxidation . Therefore, the surplus chemical heat must be removed by means of an upward water-saturated air flow that is several-fold the stoichiometric requirement for biodegradation . This study has quantified a basic process difference between anaerobic and aerobic bioconversion of organic matter: In the former, most of the chemical energy in the converted organic matter is stored chemically in the generated methane gas . In the latter, this energy is released in the cell and must be carried out in a relatively large air/water vapour flow through the cell.

Environ Toxicol Chem, 2002 Aug, 21(8), 1609 - 17
Effect of sorption and desorption resistance on aerobic trichloroethylene biodegradation in soils; Lee S et al.; Biodegradation of trichloroethylene (TCE) by toluene-degrading bacteria was measured under aerobic conditions in aqueous and soil-slurry batch microcosms . For soil-phase experiments, a freshly contaminated soil and a soil containing only the desorption-resistant fraction of TCE were tested . In both cases, presence of soil resulted in biodegradation rates substantially lower than those determined in the absence of soil . In aqueous-phase experiments, an appreciable increase in the rate and extent of TCE biodegradation was observed in microcosms when toluene was added multiple times . The TCE degradation rates were clearly correlated with toluene dioxygenase (TOD) enzyme activity over time, thus providing an indication of the cometabolic pathway employed by the microbial population . In soil-slurry experiments containing freshly contaminated soil, a TCE degradation rate of approximately 150 microg TCE/kg/h was observed during the first 39-h period, and then the TCE degradation rate slowed considerably to 0.59 and 0.84 microg TCE/kg/h for microcosms receiving one and two additions of toluene, respectively . The TCE degradation rates in soil-slurry microcosms containing the desorption-resistant fraction of TCE-contaminated soil were approximately 0.27 and 0.32 microg TCE/kg/h in microcosms receiving one and two additions of toluene, respectively . It is clear from these results that mass transfer into the aqueous phase limited bioavailability of TCE in the contaminated soil.

Water Res, 2002 Jun, 36(11), 2843 - 55
Characterization of naphthenic acids in oil sands wastewaters by gas chromatography-mass spectrometry; Holowenko FM et al.; The water produced during the extraction of bitumen from oil sands is toxic to aquatic organisms due largely to a group of naturally occurring organic acids, naphthenic acids (NAs), that are solubilized from the bitumen during processing . NAs are a complex mixture of alkyl-substituted acyclic and cycloaliphatic carboxylic acids, with the general chemical formula CnH(2n + Z)O2, where n is the carbon number and Z specifies a homologous family . Gas chromatography-electron impact mass spectrometry was used to characterize NAs in nine water samples derived from oil sands extraction processes . For each sample, the analysis provided the relative abundances for up to 156 base peaks, with each representing at least one NA structure . Plotting the relative abundances of NAs as three-dimensional bar graphs showed differences among samples . The relative abundance of NAs with carbon numbers < or = 21 to those in the "C22 + cluster" (sum of all NAs with carbon numbers > or = 22 in Z families 0 to -12) proved useful for comparing the water samples that had a range of toxicities . A decrease in toxicity of process-affected waters accompanied an increase in the proportion of NAs in the "C22 + cluster", likely caused by biodegradation of NAs with carbon numbers of < or = 21 . In addition, an increase in the proportion of NAs in the "C22 + cluster" accompanied a decrease in the total NAs in the process-affected waters, again suggesting the selective removal of NAs with carbon numbers of < or = 21 . This is the first investigation in which changes in the fingerprint of the NA fraction of process-affected waters from the oil sands operations has corresponded with measured toxicity in these waters.

Water Res, 2002 Jun, 36(11), 2695 - 702
Effect of acidity consumption/production on the pH of aeration tank during the biodegradation of acetic acid/epichlorohydrin; Yoon SH et al.; In order to elucidate the biologically driven pH fluctuation phenomena in industrial wastewater treatment, the contrary effects of acetic acid (AA) and epichlorohydrin (ECH) on the pH of aeration tank were investigated . Two simple equations were derived to estimate optimum neutralization pHs for the biological AA/ECH wastewater treatment, and the calculated optimum neutralization pHs were compared with experimental results . The pH in aeration tank was expected to fluctuate sharply with the smallest deviation of neutralization pH from the optimum value . However experimental results showed that real pH fluctuation is smaller than the theoretical one . It was considered that carbonate buffer in aqueous system relieves the pH fluctuation . The deviation between experimental and theoretical optimum neutralization pH could be mainly caused by volatility of AA and ECH . The deviation was larger with ECH wastewater of which volatility is larger than AA . Finally, this theory was successfully applied to the real petrochemical wastewater treatment . The pH of aeration tank was properly maintained when acidified wastewater (pH 3.4) was supplied.

Chemosphere, 2002 Aug, 48(5), 529 - 34
The use of inert carriers in regulatory biodegradation tests of low density poorly water-soluble substances; Handley JW et al.; Many poorly water-soluble compounds fail regulatory ready biodegradation tests as the method of test material preparation limits the bioavailability of the chemical . The recognised method for delivery of poorly soluble materials into biodegradability tests consists of coating test material inside the test vessel or onto inert substrates (i.e., glass cover slide, boiling beads, filter paper, or Teflon stir bar) that are placed inside the vessels . Volatile solvents are often used to augment this process . Although these substrates work fairly well for delivering many poorly soluble materials into biodegradability tests, they have not been effective in keeping low density, poorly water-soluble substances in the test medium . Soon after medium is added to the test vessels, these chemicals break loose from the substrates and float on the surface where they have limited contact with micro-organisms in the test medium . Hence, there is a reduced potential for measuring substantial biodegradability in the test . This paper describes the work undertaken to establish a standard method of adding low density, poorly water-soluble substances into test vessels of biodegradability studies to ensure these materials remain in contact with micro-organisms in the test medium . The substances are prepared for testing by adsorption onto silica gel followed by dispersion into the culture medium . This method of delivery may provide greater intra- and inter-laboratory consistency in biodegradability test results for low density, poorly water-soluble substances and it may more closely mimic the probable transport and fate of these substances in the environment.

Huan Jing Ke Xue, 2002 May, 23(3), 63 - 7
{Non-woven fabric media for wastewater treatment and mechanism}; Jin D et al.; Non-woven fabric was adopted as a new kind of suspended media . Adapting condition and operation parameters and biodegradation mechanism using non-woven fabric media in wastewater treatment were studied . The result of experiment shows that different CODCr volumetric load should take different media volume . When CODCr volume load was lower than 1.2 kg/(m3.d), the volume ratio of media to reactor should be 20%; the CODCr volume load between 1.2-2.0 kg/(m3.d), the volume radio of media to reactor 38%; the CODCr volume load was larger 2.0 kg/(m3.d), the volume radio of media to reactor 29% . The result of the model shows that the biodegradation rule of pollutant can be described by the format of Monod Equation.

J Hazard Mater, 2002 Aug 5, 93(3), 285 - 306
Treatment of creosote-contaminated groundwater in a peat/sand permeable barrier--a column study; Rasmussen G et al.; A column study was conducted to determine if a permeable barrier can be used to treat creosote-contaminated groundwater based on sorption and biodegradation, and to determine which processes remove the various creosote compounds . Creosote-contaminated water (sterile and non-sterile) was applied to sterile and non-sterile saturated columns with peat (20 vol.%) and sand (80 vol.%) for 2 months . Temperature was 9 degrees C, inlet oxygen concentration 9-10mg/l and average residence time was two days . The peat/sand barrier material removed 94-100% polycyclic aromatic hydrocarbons (PAHs), 93-98% nitrogen/sulfur/oxygen (NSO)-containing heterocyclic aromatic compounds, and 44-97% total phenols . The peat/sand material efficiently sorbed PAHs (>2 rings) and three-ring NSO-compounds, and also sorbed significant amounts of two-ring NSO-compounds and naphthalene . Naphthalene and NSO-compounds not sorbed were biological degraded . Phenol and cresols were efficiently removed by microbial degradation . The barrier material was somewhat less efficient removing dimethylphenols (DMPs) and trimethylphenols (TMPs), where DMPs were hardly sorbed and TMPs were hardly degraded . The results imply that a peat/sand barrier can treat creosote-contaminated groundwater . Modifications might be needed for enhanced removal of DMPs and TMPs, and oxygen supply might be necessary in aquifers with low oxygen content.

Bioresour Technol, 2002 Aug, 84(1), 15 - 20
Anaerobic biodegradation of spent sulphite liquor in a UASB reactor; Jantsch TG et al.; Anaerobic biodegradation of fermented spent sulphite liquor, SSL, which is produced during the manufacture of sulphite pulp, was investigated . SSL contains a high concentration of lignin products in addition to hemicellulose and has a very high COD load (173 g COD l(-1)) . Batch experiments with diluted SSL and pretreated SSL indicated a potential of 12-22 l methane per litre SSL, which corresponds to 0.13-0.22 l methane (g VS)(-1) and COD removal of up to 37% . COD removal in a mesophilic upflow anaerobic sludge blanket, UASB . reactor ranged from 10% to 31% at an organic loading rate, OLR, of 10-51 g (1 d)(-1) and hydraulic retention time from 3.7 to 1.5 days . The biogas productivity was 3 1 (l(reactor d)(-1), with a yield of 0.05 l gas (g VS)(-1) . These results suggest that anaerobic digestion in UASB reactors may provide a new alternative for the treatment of SSL to other treatment strategies such as incineration . Although the total COD reduction achieved is limited, bioenergy is produced and readily biodegradable matter is removed causing less load on post-treatment installations.

Chemosphere, 2002 Jul, 48(1), 89 - 96
Biodegradability testing of synthetic ester lubricants--effects of additives and usage; Eisentraeger A et al.; The optimised biodegradability test system "O2/CO2 Headspace Test with GC-TCD" is used for the assessment of synthetic ester lubricants . The effects of both additives and usage on biodegradability are examined and discussed . Ester based cutting fluids and hydraulic fluids with and without additives are used under defined conditions at machine tools and hydraulic and plain bearing test benches . The lubricants are characterised additionally with respect to kinematic viscosity, acidity and elemental composition . Furthermore, a formulated mineral oil is characterised before and after usage at an hydraulic test bench . The results clearly show that the mineral oil is far less biodegradable than the ester oils and that their biodegradability is not affected by usage . Biodegradability of the ester oils is mainly depending on the characteristics of the base fluids and not affected by the additives . Antioxidants are influencing stability respectively biodegradability indirectly, since they prevent oxopolymerisation effects . Other effects of usage on biodegradation are not detected . In this context, the antioxidants ensure ready biodegradability and have a positive effect on the environmental fate of synthetic ester lubricants.

Chemosphere, 2002 Jul, 48(1), 83 - 7
Biodegradation of technical mixtures of oxyethylenated aliphatic alcohols in an aqueous environment; Reznickova I et al.; A study of the biodegradability of nonionogenic surfactants of oxyethylenated n-butyl, isobutyl, n-pentyl and isopentyl alcohols was conducted by modified static test according to International Standard Organization method 9888 . Degradation was evaluated by changes in concentrations of individual oligomers, ethylene glycols, carboxylic and dicarboxylic acids . Good biological degradability was found, with a "primary" degradability of 75-98% in 10 days . Obtained results, in agreement with our previous work, proved the dominant proportion of degradative scission in the hydrophile part of surfactant molecule . During biological degradation no significant cumulation of mono- to polyethylene glycols appeared neither that of mono- or dicarboxylic acids, and degradation of these components was not a rate-determining degradation factor.

Chemosphere, 2002 Jul, 48(1), 117 - 31
Structural characterisation of humic acid-bound PAH residues in soil by 13C-CPMAS-NMR-spectroscopy: evidence of covalent bonds; Kacker T et al.; The fate of 13C-labelled phenanthrene and fluoranthene in different soil systems during biodegradation was studied . The soil humic acid fraction was isolated followed by structural characterisation using 13C-cross polarisation magic angle spinning nuclear magnetic resonance spectroscopy (13C-CPMAS-NMR) . It could be demonstrated that especially the ratio between the concentrations of polycyclic aromatic hydrocarbons (PAHs) and soil humus matrix limits the usefulness of this analytical tool . Based on these results a ratio of 13C-activity(PAH)/13C-activity(soil) approximately 1.5/1.0 in the test material was suggested . The chemical transformation of a PAH and its bound residue formation in a soil system detected by changes of chemical shifts in the 13C-NMR spectrum was proven for the first time . Structural information obtained by NMR spectra were verified by alkaline hydrolysis of PAH/humus-associations and following identification of cleavage products . Ester-bound phenanthrene metabolites such as 1-hydroxy-2-naphthoic acid, ortho-phthalic acid and 3,4-dihydroxybenzoic acid were detected . Additional structural assignments indicated the presence of ether-bound phenanthrene derivatives as well . Using isotopic labelling techniques a quantitative evaluation of bound residue distribution was undertaken . Fifty to seventy percent of phenanthrene metabolites which could be related to the added 13C(1)-phenanthrene were ester bound via their carboxyl groups.

Aquat Toxicol, 2002 Sep 24, 59(3-4), 191 - 200
Biodegradation and enzymatic responses in the marine diatom Skeletonema costatum upon exposure to 2,4-dichlorophenol; Yang S et al.; The biodegradation and responses of selected detoxification and antioxidant enzymes in the marine diatom, Skeletonema costatum, upon exposure to sublethal concentrations of 2,4-dichlorophenol (2,4-DCP) were investigated . Results show that 2,4-DCP was readily metabolised, but bioaccumulation and adsorption were negligible . Glutathione S-transferase, ascorbate peroxidase and superoxide dismutase activities were increased markedly after exposure to 2,4-DCP for 96 h, while no appreciable change in peroxidase activity was observed . The addition of exogeneous glutathione to diatom culture enhanced the degradation of 2,4-DCP, and promoted diatom growth . The inhibition of glutathione synthesis enhanced the toxicity of 2,4-DCP . These results suggest that glutathione conjugation was one of the principal mechanisms involved in the degradation of 2,4-DCP in this diatom.

J Biomed Mater Res, 2002 Sep 15, 61(4), 505 - 13
Biodegradation of polycarbonate-based polyurethanes by the human monocytes-derived macrophage and U937 cell systems; Matheson LA et al.; The prominent cell type found on implanted medical devices during the chronic inflammatory response is the monocyte-derived macrophage (MDM) . Using an activated in vitro cell system, it was possible to show that MDMs possess esterolytic activities that may contribute to the degradation of polyurethanes . In the present study, the U937 cell line was paralleled to the MDM cell system in order to validate the use of a cell line that could expedite studies on biomaterial biocompatibility and biostability . Using 12-o-tetradecanoylphorbol 13-acetate (PMA), the optimum differentiation time for the U937 cells was 72 h based on biodegradation, degradative potential, and (35)S-methionine uptake . After activation of the cells by resuspending from tissue culture polystyrene plates and reseeding onto a (14)C-labeled polycarbonate-based polyurethane(PCNU), both U937 cells and the MDMs elicited comparable radiolabel release (measure of polymer breakdown) and esterase activity (measure of degradative potential) at 48 h.There was no difference in the effect on radiolabel release and esterase activity elicited by both cell types with inhibitors of protein synthesis, esterase activity, and phospholipase A(2) . This established that both cell types likely used similar hydrolytic activities and signaling pathways to cause degradation of the PCNU . Immunoblotting demonstrated that both cell systems secreted monocyte-specific esterase and cholesterol esterase enzymes previously shown to degrade PCNUs . The U937 cell system is more convenient and reproducible than MDMs for pursuing possible biological pathways elucidating the mechanism of polyurethane biodegradation . Once established with U937s, the pathways can then be validated with the more physiologically relevant human MDM cell system.

Biophys J, 2002 Aug, 83(2), 776 - 93
Reaction diffusion model of the enzymatic erosion of insoluble fibrillar matrices; Tzafriri AR et al.; Predicting the time course of in vivo biodegradation is a key issue in the design of an increasing number of biomedical applications such as sutures, tissue analogs and drug-delivery devices . The design of such biodegradable devices is hampered by the absence of quantitative models for the enzymatic erosion of solid protein matrices . In this work, we derive and simulate a reaction diffusion model for the enzymatic erosion of fibrillar gels that successfully reproduces the main qualitative features of this process . A key aspect of the proposed model is the incorporation of steric hindrance into the standard Michaelis-Menten scheme for enzyme kinetics . In the limit of instantaneous diffusion, the model equations are analogous to the standard equations for enzymatic degradation in solution . Invoking this analogy, the total quasi-steady-state approximation is used to derive approximate analytical solutions that are valid for a wide range of in vitro conditions . Using these analytical approximations, an experimental-theoretical method is derived to unambiguously estimate all the kinetic model parameters . Moreover, the analytical approximations correctly describe the characteristic hyperbolic dependence of the erosion rate on enzyme concentration and the zero-order erosion of thin fibers . For definiteness, the analysis of published experimental results of enzymatic degradation of fibrillar collagen is demonstrated, and the role of diffusion in these experiments is elucidated.

Chemosphere, 2002 Jul, 48(2), 219 - 25
Degradation of organophosphoric esters in leachate from a sea-based solid waste disposal site; Kawagoshi Y et al.; Degradation of organophosphoric esters (OPEs) in leachate from a sea-based solid waste disposal site was investigated by laboratory experiment . Aryl-phosphates, tricresyl phosphate and triphenyl phosphate, in leachate rapidly decreased to less than the detection limit within 20 days under aerobic condition, suggesting high biodegradability . These phosphates also decreased in sterilized leachate, which suggested a contribution to degradation by reactions (adsorption and chemical degradation) with chemicals in the leachate . Concerning alkyl-phosphates, tributyl phosphate decreased rapidly after one week, which is considered to have been caused by biodegradation . Tris-2-ethylhexyl phosphate and tris-2-butoxyethyl phosphate decreased slowly in all samples but that of sterilized distilled water . This however, suggested contribution of biodegradation because the velocity of decrease in the leachate was higher than in control samples . Among chloro alkylphosphates, decrease of tris-2-chloroethyl phosphate and tris-dichloropropyl phosphate were observed though it was not obvious whether by biodegradation or not . Decrease of tris-2-chloropropyl phosphate (TCPP) was not observed for 80 days suggesting that TCPP remains in the leachate over a long period of time . Except for aryl-phosphates decrease of OPEs was not observed under anaerobic condition . It was considered that the composition ratio and the behavior of OPEs in leachate in the field reflects the biological and chemical degradation as well as the chemical properties of OPEs.

J Biomed Mater Res, 2002, 63(4), 408 - 12
The biodegradation mechanism of calcium phosphate biomaterials in bone; Lu J et al.; This study was undertaken to understand the biodegradation mechanisms of calcium phosphate (Ca-P) biomaterials with different crystallization . Two types of sintered Ca-P porous ceramic (HA and beta-TCP) and a Ca-P bone cement (CPC) were implanted into cavities drilled in rabbit femoral and tibiae condyles . The results have shown that a material biodegradation was rapid in the beta-TCP and the CPC, but very weak in the HA . This biodegradation presented a decrease of material volume from the periphery to the center as well as a particle formation causing phagocytosis by numerous macrophages and multinucleated giant cells in the CPC . In the beta-TCP, there was a peripheral and central decrease of material volume as well as an absence of particle formation or visible phagocytosis . The process of biodegradation is considered to be directly influenced by the type of material crystallization . The sintered bioceramics processed at a high temperature exhibit good crystallization and are primarily degraded by a process dependent on interstitial liquids . However, the bone cement is formed by physicochemical crystallization and is degraded through a dissolution process associated with a cellular process .

J Biomed Mater Res, 2002 Sep 5, 61(3), 493 - 503
Synthesis, characterization, and cytocompatibility of elastomeric, biodegradable poly(ester-urethane)ureas based on poly(caprolactone) and putrescine; Guan J et al.; The engineering of tissue for mechanically demanding applications in the cardiovascular system is likely to require mechanical conditioning of cell-scaffold constructs prior to their implantation . Scaffold properties amenable to such an application include high elasticity and strength coupled with controllable biodegradative and cell-adhesive properties . To fulfill such design criteria, we have synthesized a family of poly(ester-urethane)ureas (PEUUs) from polycaprolactone and 1,4-diisocyanatobutane . Lysine ethyl ester (Lys) or putrescine was used as chain extenders . To encourage cell adhesion, PEUUs were surface modified with radio-frequency glow discharge followed by coupling of Arg-Gly-Asp-Ser (RGDS) . The synthesized PEUUs were highly flexible, with breaking strains of 660-895% and tensile strengths from 9.2-29 MPa . Incubation in aqueous buffer for 8 weeks resulted in mass loss, from >50% (Lys chain extender) to 10% (putrescine chain extender) . Human endothelial cells cultured for 4 days with medium containing the degradation products from PEUUs with either the Lys or putrescine chain extender showed no toxic effects . Cell adhesion was 85% of that measured on tissue-culture polystyrene for unmodified PEUU surfaces (p < 0.01) and >160% (p < 0.001) of polystyrene on RGDS-modified PEUUs . These biodegradable PEUUs demonstrate potential for future application as cell scaffolds in cardiovascular tissue-engineering or other soft-tissue applications .

Biotechnol Bioeng, 2002 Jul 20, 79(2), 145 - 53
Biodegradation of crude oil across a wide range of salinities by an extremely halotolerant bacterial consortium MPD-M, immobilized onto polypropylene fibers; Diaz MP et al.; The bacterial consortium MPD-M, isolated from sediment associated with Colombian mangrove roots, was effective in the treatment of hydrocarbons in water with salinities varying from 0 to 180 g L(-1) . Where the salinity of the culture medium surpassed 20 g L(-1), its effectiveness increased when the cells were immobilized on polypropylene fibers . Over the range of salinity evaluated, the immobilized cells significantly enhanced the biodegradation rate of crude oil compared with free-living cells, especially with increasing salinity in the culture medium . Contrary to that observed in free cell systems, the bacterial consortium MPD-M was highly stable in immobilized systems and it was not greatly affected by increments in salinity . Biodegradation was evident even at the highest salinity evaluated (180 g L(-1)), where biodegradation was between 4 and 7 times higher with immobilized cells compared to free cells . The biodegradation of pristane (PR) and phytane (PH) and of the aromatic fraction was also increased using cells immobilized on polypropylene fibers .

Water Res, 2002 May, 36(9), 2243 - 54
Electrolytic oxygen generation for subsurface delivery: effects of precipitation at the cathode and an assessment of side reactions; Franz JA et al.; This research investigated the oxygen-generating characteristics and side reactions of an electrolytic cell assembly that could be used to remediate sites with contaminants that are amenable to aerobic biodegradation . The oxygen-generating capabilities of new electrolytic cells and cells with light and heavy calcium carbonate precipitates on the cathode were evaluated in the laboratory under current densities ranging from 0.5 to 5.0 mA/cm2 . Higher current densities resulted in higher mass transfer coefficients (K(L)a) and greater saturation oxygen concentrations (Csat) . As the cathodic deposits increased, the K(L)a tended to decrease and the Csat tended to increase . The oxygen transfer efficiency (OTE) did not vary as a function of current density or cathode coating, while the average OTE for all the tests was 67% . Laboratory column tests showed that chlorine production increased with current density and depended on chloride levels in the water . Hydrogen peroxide was generated at low concentrations (< 1 mg/L) and at higher levels when chloride was absent in the feed solution . Calcium removal from solution increased with current density and resulted in a decrease in solution pH . Tests at a field monitoring well showed average Csat levels of 16.9 mg/L after 14 days of operation, no chlorine production because of low chloride levels in the well, artificially elevated hydrogen peroxide levels because of background interferences, and a pH decrease of 2.4 units . With passive venting, the average hydrogen gas levels at the headspace of the well were less than 1%.

Water Res, 2002 May, 36(9), 2179 - 86
The behavior of polar aromatic sulfonates during drinking water production: a case study on sulfophenyl carboxylates in two European waterworks; Eichhorn P et al.; First investigations are reported on the efficiency of individual purification steps at two waterworks to eliminate sulfophenyl carboxylates (SPC) originating from biodegradation of linear alkylbenzene sulfonate surfactant . The average SPC concentrations in the waters taken from the Llobregat river, Spain and the Rhine river, Germany amounted to 5.0 and 1.8 microg L(-1), respectively . In the Spanish waterworks, neither prechlorination nor flocculation followed by rapid sand filtration had an impact . After ozonation, granular activated carbon filtration, and final chlorination the SPC level was about 2 microg L(-1) in such processed drinking water . In the German waterworks already the rapid sand filtration diminished the SPC concentration by >85% . Subsequent subsoil passage resulted only in a slight elimination, but once again a slow sand filtration prior to the closing chlorination substantially removed the polar micro-pollutants down to a level of <0.05 microg L(-1) SPC.

Lett Appl Microbiol, 2002, 35(2), 162 - 5
Influence of phenol on cultures of acetate-fed aerobic granular sludge; Liu Y et al.; AIMS: This paper attempts to investigate the inhibition of phenol on the acetate utilization in acetate-fed aerobic granular sludge culture . METHODS AND RESULTS: Acetate-fed aerobic granules with a mean diameter of 1.0 mm were predeveloped in a column sequencing aerobic sludge blanket reactor . The present study looked into the utilization kinetics of acetate by acetate-fed aerobic granules in the presence of different phenol concentrations ranging from 0 mg l(-1) to 50 mg l(-1) . For this purpose, batch experiments were conducted at 25 degrees C, while the initial biomass and acetate concentrations were in a range of 109-186 mg mixed liquor suspended solids (MLSS) l(-1) and 185-300 mg acetate-chemical oxygen demand (COD) l(-1) . Results showed that the utilization of acetate in the presence of phenol was subject to a zero-order reaction kinetics . The relative phenol concentration in terms of the ratio of initial phenol concentration (C(p)) to initial biomass concentration (X(0)) was used to describe the real inhibitory strength of phenol imposed on acetate-fed aerobic granules . When the C(p)/X(0) ratio increased from 0 to 0.19 mg phenol mg(-1) MLSS, the zero-order reaction rate constant of acetate dropped from 1.15 mg l(-1) min(-1) to 0.38 mg l(-1) min(-1), and a similar trend was also observed in specific oxygen utilization rate . As compared to the control test without addition of phenol, the acetate-COD removal efficiency was reduced by nearly 50% at a C(p)/X(0) value of 0.19 mg phenol mg(-1) MLSS . It was found that biodegradation of phenol was negligible in acetate-fed aerobic granular sludge batch culture . CONCLUSIONS: It appears that phenol can seriously repress the utilization of acetate in the acetate-fed aerobic granular sludge batch cultures . A simple zero-order reaction model could adequately describe the utilization of acetate by acetate-fed aerobic granules in the presence of phenol . SIGNIFICANCE AND IMPACT OF THE STUDY: It is expected that this study would lead to a better understanding of the behaviour of acetate-fed aerobic granules in the presence of inhibitory organic compounds.

Lett Appl Microbiol, 2002, 35(2), 95 - 7
Bioconversion of 3 beta-acetoxypregna-5,16-diene-20-one to androsta-1,4-diene-3,17-dione by mixed bacterial culture; Patil S et al.; AIMS: To isolate a bacterium capable of degrading 3 beta-acetoxypregna-5,16-diene-20-one (16-DPA) to androsta-1,4-diene-3,17-dione (ADD) and to decipher the biodegradation pathway . METHODS AND RESULTS: Isolation on mineral salt agar containing 16-DPA as sole carbon source yielded two bacteria identified as Pseudomonas diminuta and Comamonas acidovorons . These bacteria failed to degrade 16-DPA individually in pure cultures but converted 16-DPA to ADD in a mixed culture . The intermediates accumulated during the bioconversion were identified as pregna-4,16-diene-3,20-dione and pregna-1,4,16-triene-3,20-dione . CONCLUSIONS: The degradation pattern of 16-DPA by mixed bacterial culture revealed the reaction sequence as (i) cleavage of C-3 acetyl function, (ii) dehydrogenation at C-1 and C-2 positions and (iii) cleavage of C-17 side-chain . SIGNIFICANCE AND IMPACT OF THE STUDY: The present work opens a new approach towards the production of a female sex hormone precursor and elucidates the biodegradation pathway of 16-DPA by mixed bacterial culture.

Biomacromolecules, 2002 Jul-Aug, 3(4), 813 - 22
Anaerobic biodegradation of aliphatic polyesters: poly(3-hydroxybutyrate-co-3-hydroxyoctanoate) and poly(epsilon-caprolactone); Federle TW et al.; Poly(3-hydroxybutyrate-co-3-hydroxyoctanoate), PHBO, represents a class of PHA copolymers that contain both short-chain-length and medium-chain-length repeat units . Radiolabeled and cold PHBO, containing 90 mol % 3-hydroxybutyrate and 10 mol % 3-hydroxyoctanoate were chemically synthesized using a new difunctional alkoxyzinc initiator . (14)C-PHBO was incubated with samples of anaerobic digester sludge, septage, freshwater sediment, and marine sediment under conditions resembling those in situ . In addition, it was incubated in laboratory-scale landfill reactors . (14)C-PCL (poly-epsilon-caprolactone) was incubated with anaerobic digester sludge and in landfill reactors . Biodegradation was determined by measuring generation of (14)CO(2) and (14)CH(4) resulting from mineralization of the radiolabeled polymers . PHBO was extensively mineralized in digester sludge, septage sediments, and the landfill reactors, with half-lives less than 30 days . PCL was not significantly mineralized in digester sludge over 122 days . In the landfill reactors, PCL mineralization was slow and was preceded by a long lag period (>200 days), suggesting that PCL mineralization is limited by its rate of hydrolysis . The results indicate that PHBO is practically biodegradable in the major anaerobic habitats that it may enter . In contrast, anaerobic biodegradation of PCL is less ubiquitous and much slower.

Biomaterials, 2002 Aug, 23(16), 3473 - 8
Gelatinases in soft tissue biomaterials . Analysis of different crosslinking agents; Calero P et al.; Chemical modification of pericardium-based cardiac valves tends to reduce the relatively high degree of biodegradation and calcification of the implanted bioprostheses . We analysed the tissue properties of pericardium from young calves and pigs after crosslinking with different agents (glutaraldehyde . diphenylphosphorylazide (DDPA), 1-ethyl-3,3-dimethyl-aminopropyl-carbodiimide (EDAC)) and when exposed to anticalcification treatments (chloroform/methanol or ethanol) prior to glutaraldehyde (GA) crosslinking . Protein extraction after tissue homogenisation in the presence of detergents showed that crosslinking using GA or DPPA was much more effective . The amounts of protein extracted from these two groups of chemically modified pericardium were significantly lower: the other modified tissues presented only a slight reduction when compared with untreated tissue . Matrix metalloproteinases- (MMP) 2 and 9 were detected in native pericardium from calf and pig by zymography . While the MMP-9/MMP-2 activity ratio was close to 1 in pig pericardium, it was 8.5-fold higher in bovine tissue . Crosslinking with GA and with DPPA almost completely abolished gelatinase activities, even when equal amounts of solubilised protein were loaded onto the zymograms . Anticalcification treatments followed by GA crosslinking or treatment with EDAC were not as effective in reducing gelatinase activities; but, interestingly, a relative reduction of MMP-9 versus MMP-2 was detected . The presence of these gelatinase activities in pericardium may contribute to the in vivo degradability of pericardium-based cardiac valves.

J Environ Monit, 2002 Jun, 4(3), 435 - 41
Transport and fate of organochlorine pesticides in the River Wuchuan, southeast China; Zhang Z et al.; Persistent organic pollutants (POPs) such as chlorinated pesticides are of global concern due to their widespread occurrence, persistence, bioaccumulation and toxicity to animals and human . This paper summarises recent research on 18 chlorinated pesticides in an important catchment in China, by determining their concentrations and behaviour in water, sediment, soil and plants . The concentrations of the total pesticides were in the ranges 187-893 ng l(-1) in river water, 8.53-210 ng g(-1) dry weight in soil, 2.66-13.45 ng g(-1) dry weight in river sediment, and 651-2823 ng g(-1) dry weight in plants . The predominance of beta-HCH as the major isomer of HCHs in all water, soil, sediment and plant samples was clearly observed, due to beta-HCH's resistance to biodegradation . On average beta-HCH accounted for 44%, 53%, 50%, and 46% of the total HCH concentration in water, soil, sediment and plant, respectively . Of the DDTs, DDE accounted for 48%, 43%, 53%, 55% of the total DDT, which suggested that DDT had been transformed to its metabolites, DDE and DDD, of which DDE was the more stable . The chlorinated pesticide levels in the River Wuchuan were generally below the guideline values in China, but some sites displayed levels in excess of EC Environmental Quality Standards for HCHs and DDTs . The results therefore provide important information on the current contamination status of a key agricultural watershed in China, and point to the need for urgent actions to evaluate the long-term fate and toxicity of such persistent compounds and an appropriate remediation strategy.

Bioresour Technol, 2002 Jul, 83(3), 173 - 9
The influence of biomass temperature on biostabilization-biodrying of municipal solid waste; Adani F et al.; A laboratory study was carried out to obtain data on the influence of biomass temperature on biostabilization-biodrying of municipal solid waste (initial moisture content of 410 g kg wet weight (w.w.)(-1)) . Three trials were carried out at three different biomass temperatures, obtained by airflow rate control (A = 70 degrees C, B = 60 degrees C and C = 45 degrees C) . Biodegradation and biodrying were inversely correlated: fast biodrying produced low biological stability and vice versa . The product obtained from process A was characterized by the highest degradation coefficient (166 g kg TS0(-1); TS0(-1) = initial total solid content) and lowest water loss (409 g kg W0(-1); W0 = initial water content) . Due to the high reduction of easily degradable volatile solid content and preservation of water, process A produced the highest biological stability (dynamic respiration index, DRI = 141 mg O2 kg VS(-1); VS = volatile solids) but the lowest energy content (EC = 10,351 kJ kg w.w.(-1)) . Conversely, process C which showed the highest water elimination (667 g kg W0(-1)), and lowest degradation rate (18 g kg TS0(-1)) was optimal for refuse-derived fuel (RDF) production having the highest energy content (EC = 14,056 kJ kg w.w.(-1)) . Nevertheless, the low biological stability reached, due to preservation of degradable volatile solids, at the end of the process (DRI = 1055 mg O2 kg VS(-1)), indicated that the RDF should be used immediately, without storage . Trial B showed substantial agreement between low moisture content (losses of 665 g kg W0(-1)), high energy content (EC = 13,558 kJ kg w.w.(-1)) and good biological stability (DRI = 166 mg O2 kg VS(-1)), so that, in this case, the product could be used immediately for RDF or stored with minimum pollutant impact (odors, leaches and biogas production).

Appl Environ Microbiol, 2002 Jul, 68(7), 3514 - 21
Laccase-catalyzed oxidation of Mn(2+) in the presence of natural Mn(3+) chelators as a novel source of extracellular H(2)O(2) production and its impact on manganese peroxidase; Schlosser D et al.; A purified and electrophoretically homogeneous blue laccase from the litter-decaying basidiomycete Stropharia rugosoannulata with a molecular mass of approximately 66 kDa oxidized Mn(2+) to Mn(3+), as assessed in the presence of the Mn chelators oxalate, malonate, and pyrophosphate . At rate-saturating concentrations (100 mM) of these chelators and at pH 5.0, Mn(3+) complexes were produced at 0.15, 0.05, and 0.10 micromol/min/mg of protein, respectively . Concomitantly, application of oxalate and malonate, but not pyrophosphate, led to H(2)O(2) formation and tetranitromethane (TNM) reduction indicative for the presence of superoxide anion radical . Employing oxalate, H(2)O(2) production, and TNM reduction significantly exceeded those found for malonate . Evidence is provided that, in the presence of oxalate or malonate, laccase reactions involve enzyme-catalyzed Mn(2+) oxidation and abiotic decomposition of these organic chelators by the resulting Mn(3+), which leads to formation of superoxide and its subsequent reduction to H(2)O(2) . A partially purified manganese peroxidase (MnP) from the same organism did not produce Mn(3+) complexes in assays containing 1 mM Mn(2+) and 100 mM oxalate or malonate, but omitting an additional H(2)O(2) source . However, addition of laccase initiated MnP reactions . The results are in support of a physiological role of laccase-catalyzed Mn(2+) oxidation in providing H(2)O(2) for extracellular oxidation reactions and demonstrate a novel type of laccase-MnP cooperation relevant to biodegradation of lignin and xenobiotics.

Microb Ecol, 2002 Aug, 44(2), 107 - 17 Epub 2002 Jun 28.
Geochemical and physiological evidence for mixed aerobic and anaerobic field biodegradation of coal tar waste by subsurface microbial communities; Bakermans C et al.; We used geochemical analyses of groundwater and laboratory-incubated microcosms to investigate the physiological responses of naturally occurring microorganisms to coal-tar-waste constituents in a contaminated aquifer . Waters were sampled from wells along a natural hydrologic gradient extending from uncontaminated (1 well) into contaminated (3 wells) zones . Groundwater analyses determined the concentrations of carbon and energy sources (pollutants or total organic carbon), final electron acceptors (oxygen, nitrate, sulfate), and metabolic byproducts (dissolved inorganic carbon {DIC}, alkalinity, methane, ferrous iron, sulfide, Mn2+) . In the contaminated zone of the study site, concentrations of methane, hydrogen, alkalinity, and DIC were enhanced, while dissolved oxygen and nitrate were depleted . Field-initiated biodegradation assays using headspace-free serum bottle microcosms filled with groundwater examined metabolism of the ambient organic contaminants (naphthalene, 2-methylnaphthalene, benzothiophene, and indene) by the native microbial communities . Unamended microcosms from the contaminated zone demonstrated the simultaneous degradation of several coal-tar-waste constituents at the in situ temperature (10 degrees C) . Lag phases prior to the onset of biodegradation indicated the prevalence of both aerobic and anaerobic conditions in situ . Electron acceptor-amended microcosms from the most contaminated well waters demonstrated only aerobic naphthalene degradation . Collectively, the geochemical and microbial evidence show that biodegradation of coal-tar-waste constituents occurs via both aerobic and anaerobic terminal electron accepting processes at this site.

Biomed Sci Instrum, 2002, 38, 145 - 50
Stress state during fixation determines susceptibility to fatigue-linked biodegradation in bioprosthetic heart valve materials; Margueratt SD et al.; Mechanical loading contributes to the structural deterioration of bioprosthetic heart valves . The influence of stress state during fixation may play a substantial role in their failure, linking fatigue damage caused by buckling and tension and the enzymatic degradation of glutaraldehyde-crosslinked collagen . Bovine pericardia were obtained immediately postmortem and 100 mm x 15 mm samples were cut in the base-to-apex direction . Half the samples were subjected to a uniaxial tensile stress of 250 kPa and half remained unloaded during a crosslinking treatment in 0.5% glutaraldehyde . Tissue samples were rinsed and cut into 16 mm x 4 mm test strips . Half of these strips were exposed to cyclic compressive buckling and alternating tension at 30 Hz for 20 million cycles (approx . 7.5 days) using a custom-built multi-sample fatigue system . Fatigue-damaged and non-damaged samples were subsequently incubated at 37 C for 48 hrs in: (i) Type I bacterial collagenase (20 U/ml) buffered in 0.05 M Tris, 10 mM CaCl2 2H2O (pH 7.4) or (ii) 0.05 M Tris buffer (pH 7.4) only . In both cases, the samples were loaded sinusoidally between 40 and 80 g using a previously described microtensile culture system . Tissue removed from the bath was rinsed in 0.1 M EDTA solution and mounted in a servo-hydraulic mechanical testing system (MTS) . Ultimate tensile strength (UTS), maximum tissue modulus, and fracture strain were determined . The percent collagen solubilized was assessed by a colourmetric hydroxyproline assay of the enzyme bath and tissue sample . All data were analyzed by analysis of variance (ANOVA) . The results confirmed the synergy between fatigue damage and collagenase proteolysis in these materials; however, there were no significant differences in this effect between simple fixation and stress-fixation up to 20 million cycles . There were significant decreases in the mechanical properties and an increase in the amount of collagen solubilized with increased exposure to fatigue cycling.

Environ Sci Technol, 2002 Jun 1, 36(11), 2464 - 70
Hydrogen isotopic enrichment: an indicator of biodegradation at a petroleum hydrocarbon contaminated field site; Mancini SA et al.; Compound-specific carbon and hydrogen isotope analysis was used to investigate biodegradation of benzene and ethylbenzene in contaminated groundwater at Dow Benelux BV industrial site . delta13C values for dissolved benzene and ethylbenzene in downgradient samples were enriched by up to 2+/-0.5 per thousand, in 13C, compared to the delta13C value of the source area samples . delta2H values for dissolved benzene and ethylbenzene in downgradient samples exhibited larger isotopic enrichments of up to 27+/-5 per thousand for benzene and up to 50+/-5 per thousand for ethylbenzene relative to the source area . The observed carbon and hydrogen isotopic fractionation in downgradient samples provides evidence of biodegradation of both benzene and ethylbenzene within the study area at Dow Benelux BV . The estimated extents of biodegradation of benzene derived from carbon and hydrogen isotopic compositions for each sample are in agreement, supporting the conclusion that biodegradation is the primary control on the observed differences in carbon and hydrogen isotope values . Combined carbon and hydrogen isotope analyses provides the ability to compare biodegradation in the field based on two different parameters, and hence provides a stronger basis for assessment of biodegradation of petroleum hydrocarbon contaminants.

SAR QSAR Environ Res, 2002 Mar, 13(1), 199 - 204
Prediction of biodegradability from structure: imidazoles; Rorije E et al.; A project for the development of Structure-Activity Relationship for Biodegradation is presented . The aim of the project is to assemble sets of structural rules governing the potential microbial degradability of (classes of) chemicals . These rules will provide tools to take into account the biodegradation aspects of a product--and all precursors in the production process--early in the product development . The modeling concept is to take all experimental biodegradation data available and combine structural trends in the data with mechanistical information from degradation pathways . The rules that are derived should give insight into the possibility of biodegradation for specific classes of chemicals, thereby revealing why a compound is biodegradable or not . For the class of imidazole derivatives such rules are derived, and a model degradation mechanism is proposed in analogy to the urocanate-hydratase mechanism from histidine metabolism . The model is validated using 12 imidazole-compounds, which are all predicted correctly to be poorly biodegradable . It is demonstrated that both data analysis and information on enzymatic reaction mechanisms are necessary to yield valid Structure-Biodegradation Relationship.

J Ind Microbiol Biotechnol, 2002 Mar, 28(3), 168 - 72
Influence of aromatic compounds on biodegradation of {14C}-labeled xylan and mannan by the white-rot fungus Phlebia radiata; Rogalski J et al.; Radiolabeled {14C}arabinoxylan from wheat meal and {14C}galactoglucomannan from red clover meal were prepared by using 14CO2 as a precursor . Twice as much mannan was mineralized than xylan after 14 days of incubation with Phlebia radiata . Low-molecular-weight phenolic compounds structurally related to lignin increased during mineralization of both hemicellulose fractions . Veratryl alcohol increased degradation of arabinoxylan by approximately 28.5%, whereas veratric acid increased it by only 9.0% . Vanillic acid and ferulic acid also stimulated degradation by 16.6% and 34.7%, respectively . Veratryl alcohol and ferulic acid increased degradation of galactoglucomannan by approximately 75% . Veratraldehyde in both cases repressed the degradation process (23.6% arabinoxylan, 43.8% galactoglucomannan) . These results indicate that the degradation of hemicelluloses, e.g., xylan and mannan, by P . radiata is enhanced by addition of aromatic compounds.

Environ Microbiol, 2002 Jun, 4(6), 327 - 37
A chlorophyll a fluorescence-based Lemna minor bioassay to monitor microbial degradation of nanomolar to micromolar concentrations of linuron; Hulsen K et al.; A plant-microbial bioassay, based on the aquatic macrophyte Lemna minor L . (duckweed), was used to monitor biodegradation of nano- and micromolar concentrations of the phenylurea herbicide linuron . After 7 days of exposure to linuron, log-logistic-based dose-response analysis revealed significant growth inhibition on the total frond area of L . minor when linuron concentrations > or = 80 nM were added to the bioassay . A plant-protective effect was obtained for all concentrations > 80 nM by inoculation with either a bacterial consortium or Variovorax paradoxus WDL1, which is probably the main actor in this consortium . The outcome of the plant-microbe-toxicant interaction was also assessed using pulse amplitude-modulated chlorophyll a fluorescence and chlorophyll a fluorescence imaging . Linuron toxicity to L . minor became apparent as a significant decrease in the effective quantum yield (Delta F/Fm') within 90 min after exposure of the plants to linuron concentrations > or = 160 nM . Inoculation of the bioassay with the linuron-degrading bacteria neutralized the effect on the effective quantum yield at concentrations > or = 160 nM, indicating microbial degradation of these concentrations . The chlorophyll a fluorescence-based Lemna bioassay described here offers a sensitive, fast and cost-effective approach to study the potential of biodegrading microorganisms to break down minute concentrations of photosynthesis-inhibiting xenobiotics.

SAR QSAR Environ Res, 2002 Mar, 13(2), 307 - 23
Probabilistic assessment of biodegradability based on metabolic pathways: catabol system; Jaworska J et al.; A novel mechanistic modeling approach has been developed that assesses chemical biodegradability in a quantitative manner . It is an expert system predicting biotransformation pathway working together with a probabilistic model that calculates probabilities of the individual transformations . The expert system contains a library of hierarchically ordered individual transformations and matching substructure engine . The hierarchy in the expert system was set according to the descending order of the individual transformation probabilities . The integrated principal catabolic steps are derived from set of metabolic pathways predicted for each chemical from the training set and encompass more than one real biodegradation step to improve the speed of predictions . In the current work, we modeled O2 yield during OECD 302 C (MITI I) test . MITI-I database of 532 chemicals was used as a training set . To make biodegradability predictions, the model only needs structure of a chemical . The output is given as percentage of theoretical biological oxygen demand (BOD) . The model allows for identifying potentially persistent catabolic intermediates and their molar amounts . The data in the training set agreed well with the calculated BODs (r2 = 0.90) in the entire range i.e . a good fit was observed for readily, intermediate and difficult to degrade chemicals . After introducing 60% ThOD as a cut off value the model predicted correctly 98% ready biodegradable structures and 96% not ready biodegradable structures . Crossvalidation by four times leaving 25% of data resulted in Q2 = 0.88 between observed and predicted values . Presented approach and obtained results were used to develop computer software for biodegradability prediction CATABOL.

Environ Toxicol Chem, 2002 Jun, 21(6), 1236 - 42
Fate and bioaccumulation of isoproturon in outdoor aquatic microcosms; Merlin G et al.; To gain information concerning the ecotoxicity of isoproturon (IPU) on aquatic ecosystems, six experimental ponds of 5 m3 each were studied . All the experiments were conducted during the summer over two years . Three different types of ecosystems were tested in 1994 and one type of ecosystem was selected and repeated in 1995 with three replicates . In each case, the initial concentration of IPU contamination was set at 10 microg/L . The IPU concentration was determined in the water column and in different species (mainly plants) of the microcosms . A first-order kinetic decrease in IPU concentration was observed in 1994, with half-life ranging from 15 to 35 d, depending on the microcosms . This relatively fast decrease was also confirmed in 1995, but it reached a constant value after two months . A high variability of the IPU concentration was observed in exposed plants, with bioconcentration factors ranging from 100 to 1,200 with large coefficients of variation . The observed plant bioconcentration factors are higher than those predicted by usual numerical models, probably due to the specific binding of IPU on one protein of the photosynthetic apparatus . Our data show that bioconcentration does not occur in mollusks but is important in photosynthetic organisms . Plant bioconcentration and microbial biodegradation are the main processes involved in the IPU decay in our outdoor aquatic microcosms.

J Agric Food Chem, 2002 Jun 19, 50(13), 3623 - 31
Deactivation of the biological activity of paraquat in the soil environment: a review of long-term environmental fate; Roberts TR et al.; During the many years of paraquat usage, wide ranges of investigations of its environmental impact have been conducted . Much of this information has been published, but key, long-term field studies have not previously been presented and assessed . The purpose of this review is to bring together and appraise this information . Due to the nature of paraquat residues in soils, the major part (some 99.99%) of a paraquat application that reaches the soil within the typical Good Agricultural Practice (GAP) is strongly adsorbed to soils of a wide variety of textures . This is in equilibrium with an extremely low concentration in soil solution . However, the paraquat in soil solution is intrinsically biodegradable, being rapidly and completely mineralized by soil microorganisms . The deactivation of the biological activity of paraquat in soils, due to sorption, has been investigated thoroughly and systematically . It is recognized that the determination of total soil residues by severe extraction procedures provides no insight into the amount of paraquat biologically available in soil . Consequently, the key assay developed for this purpose, namely, the strong adsorption capacity-wheat bioassay (SAC-WB) method, has proved to be valuable for determination of the adsorption capacity relevant to paraquat for any particular soil . This method has been validated in the field with a series of long-term (>10 years) trials in different regions of the world . These trials have also shown that, following repeated applications of very high levels of paraquat in the field, residues not only reach a plateau but also subsequently decline . This demonstrates that the known biodegradation of paraquat in soil pore water plays an important role in field dissipation . The biological effects of paraquat in the field have been assessed under unrealistically high treatment regimes . These trials have demonstrated that the continued use of paraquat under GAP conditions will have no detrimental effects on either crops or soil-dwelling flora and fauna . Any such effects can occur only under extreme use conditions (above the SAC-WB), which do not arise in normal agricultural practice.

J Chromatogr A, 2002 Apr 12, 953(1-2), 215 - 25
Determination of benzylsuccinic acid in gasoline-contaminated groundwater by solid-phase extraction coupled with gas chromatography-mass spectrometry; Reusser DE et al.; Benzylsuccinic acid (BSA) and methylbenzylsuccinic acid (methyl-BSA) are unambiguous biotransformation products resulting from anaerobic toluene and xylene biodegradation, respectively . A solid-phase extraction method based on polystyrene-divinylbenzene sorbent was developed for the quantitative BSA determination in groundwater samples as an alternative to liquid-liquid extraction . Gas chromatography coupled with mass spectrometry was used for separation and detection . The recovery from spiked 11 groundwater samples was 88 to 100% . The precision of the method, indicated by the relative standard deviation, was +/- 4% and the method detection limit was 0.2 microg/l . The concentration of BSA and methyl-BSA in groundwater samples from anaerobic BTEX (benzene, toluene, ethylbenzene and xylenes)-contaminated sites ranged from below the detection limit (3 microg/l) to 155 microg/l.

Waste Manag Res, 2002 Apr, 20(2), 134 - 42
Vermicomposting of a lignocellulosic waste from olive oil industry: a pilot scale study; Benitez E et al.; The vermicomposting with Eisenia andrei of dry olive cake, a lignocellulosic waste produced during the extraction of olive oil, either alone or mixed with municipal biosolids, was studied in a nine-month pilot scale experiment . Number and biomass of earthworms and enzyme activities were periodically monitored and relevant properties of the final products were determined . In the assayed substrates, the total biomass of earthworms increased at the end of the experimental period between 9 and 12-fold respectively in comparison with the earthworm biomass initially inoculated . The increase in hydrolytic enzymes and overall microbial activity during the vermicomposting process indicated the biodegradation of the olive cake and resulted in the disappearance of the initial phytotoxicity of the substrate . However, the recalcitrant lignocellulosic nature of the dry olive cake prevented suitable humification during the vermicomposting process . For this reason, in addition to organic amendments, other management procedures should be considered.

Curr Opin Microbiol, 2002 Jun, 5(3), 266 - 73
Bacterial chemotaxis to pollutants and plant-derived aromatic molecules; Parales RE et al.; There is accumulating evidence that motile bacteria are chemotactically attracted to environmental pollutants that they can degrade . Chemotaxis, the ability of motile bacteria to detect and respond to specific chemicals in the environment, can increase an organism's chances of locating useful sources of carbon, nitrogen and energy, and could thus play an important role in the biodegradation process . Recent evidence demonstrating that chemotaxis and biodegradation genes are coordinately regulated suggests that these processes are intimately linked in nature.

Folia Histochem Cytobiol, 2002, 40(2), 181 - 2
Thyroid C cells in male and female rats with chronic renal failure; Kasacka L et al.; The kidneys are responsible for iodine and of thyroid hormone biodegradation . The aim of this study was the histomorphological and immunohistochemical evaluation of the influence of sex on parafollicular thyroid C cells in rats with chronic renal failure . The experiment included 40 Wistar rats after subtotal nephrectomy, after sham operation, and without any surgical procedure . Two weeks after nephrectomy, fragments of thyroids were collected from the examined animals . Paraffin sections were stained with H+E and by silver impregnation . Calcitonin (CT), synaptophysin (SPh), somatostatin (ST), and neuron-specific enolase (NSE) were detected immunohistochemically in C cells . In rats with experimental uremia, immunostaining for the examined substances increased significantly in comparison to the controls . We also observed higher number of C cells with a stronger reaction in the group of males, compared to the female rats.

Biochem Biophys Res Commun, 2002 May 3, 293(2), 832 - 5
The mediation of veratryl alcohol in oxidations promoted by lignin peroxidase: the lifetime of veratryl alcohol radical cation; Baciocchi E et al.; The kinetics of decay of veratryl alcohol radical cation, generated by cerium(IV) ammonium nitrate induced oxidation of veratryl alcohol, have been followed spectrophotometrically in a stopped-flow apparatus . In acidic aqueous acetonitrile the radical cation was found to decay by a first-order process, due to deprotonation from the alpha-carbon leading to an alpha-hydroxybenzyl radical with the rate constant of 17.1+/-0.5 s(-1) . This value is in full agreement with those obtained by pulse radiolysis studies but much lower than the value (1.2x10(3) s(-1)) indirectly determined by EPR experiments . The implications of these results with respect to the possible role of veratryl alcohol as a mediator in the oxidative biodegradation of lignin catalysed by lignin peroxidase are discussed .

Sheng Wu Hua Xue Yu Sheng Wu Wu Li Xue Bao (Shanghai), 2001, 33(1), 13 - 18
Non-hydrolytic Disruption of Crystalline Structure of Cellulose by Cellulose Binding Domain and Linker Sequence of Cellobiohydrolase I from Penicillium janthinellum; Gao PJ et al.; The cooperation between cellobiohydrolase (CBHI) and endoglucanase (EG) is necessary for biodegradation of native cellulose, but its mechanism is still poorly understood . The present paper report at the first time that an isolated component, the cellulose binding domain with its linker sequence of cellobiohydrolase I from Penicillium janthinellum (CBD(CBHI)), plays an important role in the synergism between CBHI and EGI during cellulose biodegradation . A recombinantplasmid (pUC18C), containing the gene fragment encoding CBD(CBHI) from P.janthinellum was derived from pUC18-181 . In pUC 18C, the catalytic domain region of cbhI gene was deleted by in vitro DNA manipulations and then E.coli JM 109 was transformed for the production of LacZ-CBD fusion protein . The active LacZ-CBD fusion protein was digested by papain and then purified by re-exclusion chromatography . The purified peptide sequence of CBD(CBHI) had the ability of binding crystalline cellulose . The detailed morphological and structural changes of cotton fibers after binding CBD(CBHI) were investigated by using scanning electron microscopy, calorimetric activity and X-ray diffraction . The results demonstrated that the CBD(CBHI) not only has a high binding capacity to cellulose, but also causes non-hydrolytic disruption of crystalline cellulose, which leads to the release of short fibers . IR spectroscopy and X-ray diffraction show that destabilization is caused by the non-hydrolytic disruption of cellulose and the disruption of hydrogen bonds in crystalline cellulose . The efficiency of crystalline cellulose degradation was enhanced by synergistic action of CBD(CBHI) with EGI . These results suggest that the cellulose-binding domain with its linker plays an important role in crystalline cellulose degradation.

Toxicol Lett, 2002 Feb 28, 127(1-3), 259 - 67
Biodegradability of inhaled p-aramid respirable fiber-shaped particulates (RFP): mechanisms of RFP shortening and evidence of reversibility of pulmonary lesions; Warheit DB et al.; These studies elucidated mechanisms of inhaled p-aramid respirable fiber-shaped particulates (RFP) biodegradation in the lungs of exposed rats and hamsters . We postulate that lung fluids coat/activate inhaled p-aramid RFP which deposits in the lung and promote enzymatic attack and consequent shortening . p-Aramid or cellulose (biopersistent control) RFP were instilled into the lungs of rats and the lungs digested 24 h later using two different (KOH or enzymatic) digestion techniques . In vivo, the enzyme but not the KOH solution produced shortening of p-aramid but not cellulose RFP recovered from the lungs . For in vitro studies, the two RFP-types were incubated with BAL fluids and underwent simulated digestions; also rat lung epithelial cells, macrophages or co-cultures were incubated with p-aramid and digested at 1, 24, or 168 h postexposure . The results of in vitro acellular studies demonstrated that only p-aramid RFP incubated in BAL fluids and digested by the enzyme method were shortened . In vitro cellular studies demonstrated a shortening of p-aramid RFP in macrophages and co-cultures but not in lung epithelial cells at 24 h and 1 week postexposure . These results demonstrate that lung fluids coat and catalyze the p-aramid RFP as a prelude for shortening and describe a likely mechanism for the biodegradability of inhaled p-aramid RFP in the lungs of exposed animals.

Biotechnol Prog, 2002 May-Jun, 18(3), 429 - 36
Enhanced-rate biodegradation of organophosphate neurotoxins by immobilized nongrowing bacteria; Kim JW et al.; Pesticide wastes generated from livestock dipping operations containing the organophosphate (OP) insecticide coumaphos (CP) are well suited for disposal by biodegradation since they are highly concentrated (approximately 1 g/L), generally contained, and lack additional toxic components . In this study, a significantly enhanced efficiency of degrading CP in cattle dip waste (CDW) is reported using a dense, nongrowing cell population that functions without the addition of nutrients required for growing cell cultures . A recombinant strain of Escherichia coli containing the opd gene for organophosphate hydrolase (OPH), which is capable of active hydrolysis of OP neurotoxins including CP, was cultivated in a rich medium containing all essential nutrients . Cells were harvested and utilized in lab scale experiments in the form of either freely suspended cells or cells immobilized within a macroporous gel matrix, poly(vinyl alcohol) (PVA) cryogel . Significantly higher degradation rates were achieved with either suspended or immobilized OPH(+) cells compared to rates with the microbial consortium naturally present in CDW . Of the two nongrowing cell systems, the detoxification rate with immobilized cells was approximately twice that of freely suspended cells, and kinetic studies demonstrated that a higher maximum reaction rate was achieved with the immobilized cell system . A comparative study using both the CDW and pure CP substrates with free cells indicated that the CDW contained one or more factors that reduced the bioavailability of CP . The immobilized cells retained their activity over a 4-month period of use and storage, demonstrating both sustained catalytic activity and long-term mechanical stability.

Ecotoxicol Environ Saf, 2002 May, 52(1), 75 - 81
Joint toxicity of linear alkylbenzene sulfonates and pyrene on Folsomia fimetaria; Jensen J et al.; Surfactants may enhance the biodegradation of hydrophobic substances in soils . This has partly been attributed to an increase in the bioavailability, brought about by the presence of surfactants . The aim of this study was to examine the ecotoxicological effects of the detergent linear alkylbenzene sulfonate (LAS) and the polycyclic aromatic hydrocarbon pyrene, alone and in combination, using the survival and reproduction of the collembolan Folsomia fimetaria as endpoints . The EC(50) and EC(10) were 803 and 161 mg kg(-1) for LAS, and 23 and 15 mg kg(-1) for pyrene . If LAS was able to increase the bioavailability of pyrene to springtails, it was expected that the combined effect of the two substances would exceed the effect found for each of the compounds tested separately . However, the results showed no effect of LAS on the toxicity of pyrene in the concentration range tested (1-750 mg LAS kg(-1) dry weight) . Both the toxic unit concept and the isobologram method indicated that an additive approach would be the most useful when assessing the risk of these two compounds.

Biodegradation, 2001, 12(6), 433 - 42
Naphthalene, phenanthrene and surfactant biodegradation; Chen G et al.; The impact of surfactants on naphthalene and phenanthrene biodegradation and vice versa after surfactant flushing were evaluated using two anionic surfactants: sodium dodecyl sulfate (SDS) and sodium dodecyl benzene sulfonate (SDBS); and two nonionic surfactants: POE (20) sorbitan monooleate (T-maz-80) and octylphenol poly(ethyleneoxy) ethanol (CA-620) . Naphthalene and phenanthrene biodegradation varied differently in the presence of different surfactants . Naphthalene biodegradation was not impacted by the presence of SDS . In the presence of T-maz-80 and CA-620, naphthalene biodegradation occurred at a lower rate (0.14 d(-1) for T-maz-80 and 0.19 d(-1) for CA-620) as compared to un-amended control (0.29 d(-1)) . Naphthalene biodegradation was inhibited by the presence of SDBS . In the presence of SDS, phenanthrene biodegradation occurred at a lower rate (0.10 d(-1) as compared to un-amended control of 0.17 d(-1)) and the presence of SDBS, CA-620 and T-maz-80 inhibited phenanthrene biodegradation . The surfactants also responded differently to the presence of naphthalene and phenanthrene . In the presence of naphthalene, SDS biodegradation was inhibited; SDBS and T-maz-80 depleted at a lower rate (0.41 d(-1) and 0.12 d(-1) as compared to 0.48 d(-1) and 0.22 d(-1)) . In the absence of naphthalene, CA-620 was not degradable, while in the presence of naphthalene, CA-620 began to degrade at a comparatively low rate (0.12 d(-1)) . In the presence of phenanthrene, SDS biodegradation occurred at a lower rate (1.2 d(-1) as compared to 1.68 d(-1)) and a similar trend was observed for T-maz-80 . The depletion of SDBS and CA-620 did not change significantly . The choice of SDS for naphthalene-contaminated sites would not adversely affect the natural attenuation of naphthalene, in addition, naphthalene was preferentially utilized to SDS by naphthalene-acclimated microorganisms . Therefore, SDS was the best choice . T-maz-80 was also found to be usable in naphthalene-contaminated sites . For phenanthrene contaminated sites, SDS was the only choice.

Biodegradation, 2001, 12(6), 419 - 32
Degradation of dissolved and sorbed 2,4-dichlorophenol in soil columns by suspended and sorbed bacteria; Bengtsson G et al.; The influence of sorption of bacteria, as well as 2,4-dichlorophenol (2,4-DCP), on the mineralization of 100 microg l(-1) of the organic compound was examined in an aquifer material under advective flow conditions (column displacement technique) . The study was designed to distinguish the rates and extent of biodegradation of the sorbed and the dissolved trace organic and the contribution of sorbed and suspended bacteria to the degradation . The degradation of dissolved 2,4-DCP was significantly faster than the degradation of the same compound sorbed to the solids, and suspended bacteria degraded the dissolved compound at a higher rate than sorbed bacteria, also on a per cell basis . The suspended bacteria degraded 8-12% of the added dissolved 2.4-DCP, while sorbed bacteria made a smaller contribution by degrading about 5% of sorbed 2,4-DCP . No degradation was seen with sorbed 2,4-DCP and suspended bacteria, and a marginal contribution was made by sorbed bacteria on the degradation of dissolved 2,4-DCP (<0.4%).

Biodegradation, 2001, 12(6), 379 - 91
Detection of intermediate metabolites of benzene biodegradation under microaerophilic conditions; Yerushalmi L et al.; The intermediate metabolites of benzene transformation by a microaerophilic bacterial consortium, adapted to degrade gasoline and benzene at low concentrations of dissolved oxygen (<1 mg l(-1)), were identified . The examined range of initial DO concentration, 0.05 to 1 mg l(-1), was considerably lower than the previously reported values believed to be necessary to initiate benzene biodegradation . An extensive transformation of benzene . higher than the theoretical predictions for its aerobic oxidation, was observed . Phenol was identified as the most stable and the major intermediate metabolite which was subsequently transformed into catechol and benzoate . The use of 13C-labeled compounds identified benzene as the source of phenol, and phenol as the source of catechol and benzoate, suggesting the involvement of a monooxygenase enzymatic system in biodegradation of benzene at low DO concentrations . A metabolic sequence was proposed to describe the simultaneous detection of catechol and benzoate during the microaerophilic transformation of benzene . The results of this work demonstrate that it is possible to transform benzene, a highly carcinogenic hydrocarbon and a major contaminant of groundwater, to more easily biodegradable compounds in the presence of very small amounts of oxygen.

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