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PubMed2003

Contribution of metabolites to mutagenicity during anaerobic biodegradation of fenitrothion.

The contribution of fenitrothion and its microbial metabolites to the mutagenicity of a fenitrothion-containing solution was investigated during anaerobic biodegradation. Although a mixed culture of bacteria obtained from a paddy field degraded fenitrothion and reduced its concentration from 4.6 to 0.1 mg/l in 6 days, the indirect mutagenicity of the solution in Salmonella strain YG1029 increased. This increase was found to be partially due to amino-fenitrothion generated during the biodegradation. In addition, other unidentified metabolites contributed to the mutagenicity. In contrast, the indirect mutagenicity in strain YG1042, which was initially large because of fenitrothion, then decreased, and increased again. This increase in mutagenicity was also due to amino-fenitrothion and other unidentified metabolites. The mutagenicity in strains YG1029 and YG1042 decreased after day 6. The greatest contribution of amino-fenitrothion to the mutagenicity was calculated to be 73% and 61% in YG1029 and YG1042 on day 3 of incubation, respectively. That of unidentified metabolites was calculated at 49% and 61% on day 20, respectively. Therefore, because not all the toxic metabolites of a compound can be identified, it is important to evaluate the toxicity of a whole solution in a bioassay such as the Ames assay rather than deducing the toxicity of the solution from the combined toxicities of known metabolites.

Anaerobiosis↗

PubMed2003

Biodegradability of Atrazine, Cyanazine and Dicamba under methanogenic condition in three soils of China.

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

Atrazine↗

PubMed2003

Ecotoxicity and biodegradation of phthalate monoesters.

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

Animals↗

PubMed1997

Comparison of the QSAR models for toxicity and biodegradability of anilines and phenols.

Structure-activity models for toxicity and biodegradability of groups of m-anilines and p-phenols were developed and compared. Hydrophobicity was the most important property in determining toxicity. Whereas, electronic and steric properties were the more important in modeling biodegradation.

Aniline Compounds↗

PubMed1998

Pentachlorophenol and phenanthrene biodegradation in creosote contaminated aquifer material.

Contamination of the subsurface environment at the Libby Superfund Site, Montana, includes polycyclic aromatic hydrocarbons and f1p4achlorophenol due to accidental spills and improper disposal of wood preserving wastes. Biodegradation is a treatment technology gaining wide application in the treatment of hazardous waste sites. A microcosm study was conducted to evaluate the effect of temperature, sampling depth, nutrient addition, and oxygen on the biodegradation potential of phenanthrene and pentachlorophenol in aquifer samples using radiolabeled chemicals. Mineralization of phenanthrene reached 14% but was less than 1% for pentachlorophenol over the 56 day incubation period. Phenanthrene mineralization in microcosms at 10 degrees C was not significantly different from those at 20 degrees C. This may have been due to microbial community acclimation to lower temperatures at the site. Average volatilization was less than 2% for both phenanthrene and pentachlorophenol. After 56 days, most of the radiolabeled chemical was either solvent extractable or soil bound.

Biodegradation, Environmental↗

PubMed1998

The 'two-phase closed bottle test'--a suitable method for the determination of 'ready biodegradability' of poorly soluble compounds.

The Two-Phase Closed Bottle test (BODIS test) is a cost-effective supplement of the existing OECD tests for ready biodegradability (OECD 301) due to its entire compatibility with them and its particular suitability for testing poorly soluble compounds. The comparison of a number of test data from this and other ready biodegradability tests showed that the BODIS test has a similar stringency in terms of the attainment of the pass level and the time window criterion as well. A significant influence of the strength of the bacterial inoculum on the test results was not observed.

Bacteria, Aerobic↗

PubMed1998

Pretreatment and biodegradability enhancement of DSD acid manufacturing wastewater.

Two advanced oxidation processes, Fenton's reagent oxidation and ozonation, were used for pretreatment of a 4,4'-diaminostilbene-2,2'-disulfonic acid (DSD-acid) manufacturing wastewater on a laboratory scale. The results showed that both methods are suitable for partial removal of chemical oxygen demand (COD) and color as well as the enhancement of biodegradability of DSD-acid manufacturing wastewater before the conventional biological treatment. Fenton's reagent oxidation by 9.0 g/L H2O2 and 150 mg/L Fe2+ and ozonation by 7.5 g/L O3 led to an improved biodegradability (BOD5/COD = 0.3). Fenton's reagent oxidation in combination with Fe3+ coagulation has shown to effectively remove COD and color. About 90% of COD and 95% of color removals were obtained at the optimum condition, oxidation by 150 mg/L Fe2+ and 2 g/L H2O2, followed by two-stage coagulation with 5 g/L and 2 g/L FeCl3, respectively.

4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfo↗

PubMed1999

Aerobic biodegradation of dichloroethylenes in surface and subsurface soils.

Laboratory studies were conducted to examine the aerobic biodegradation of dichloroethylenes (cis-1,2-DCE, trans-1,2-DCE and 1,1-DCE) in soil and groundwater. Authentic surface and subsurface materials with no reported DCE exposure history were used. All DCE isomers were observed to biodegrade to varying degrees in the soils examined. Use of radiolabeled [14C] test chemicals allowed correlation of DCE disappearance with mineralization to 14CO2. Study results indicate that naturally occurring microorganisms in soil and groundwater are capable of degrading cis-1,2-, trans-1,2- and 1,1-DCE without laboratory supplementation of exogenous organic nutrients, or previous exposure history. The data further suggest that degradative potential may vary with soil type, DCE isomer structure, and concentration.

Aerobiosis↗

PubMed1999

Enhancement of PAH biodegradation in soil by physicochemical pretreatment.

The effects were studied of short-term heating of contaminated soil and its soaking in an organic solvent on the subsequent biodegradation of PAHs. In a clayey dredged sludge with a high organic-matter content (12%), heating at 120 degrees C for one hour increased the degree of degradation after 21 days of an aged PAH contamination from 9.5 +/- 0.7% to 27 +/- 5%. Lower temperatures resulted in smaller increases. The observed increase in biodegradation is caused by either transfer of PAHs from sorption sites with low desorption rates to those with high ones or transformation of slow-sorption sites into fast-sorption ones. Soaking of the above sludge in a 4:1 (v/v) acetone-water mixture increased the degree of degradation from 9.5 +/- 0.7% to 20.4 +/- 1.4%, probably as a result of dissolution of the PAHs in the pore liquid during soaking. Thermal pretreatment of a contaminated sandy soil with a low organic-matter content showed no significant effect on the degradation of aged PAHs. Soaking of the sandy soil increased the degradation of only PAHs of high molecular weight, namely from 24 +/- 5% to 48 +/- 7%.

Acetone↗

PubMed2000

Effects of heterocyclic PAHs (N, S, O) on the biodegradation of typical tar oil PAHs in a soil/compost mixture.

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

Biodegradation, Environmental↗

PubMed2000

An automated test for measuring polymer biodegradation.

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

Automation↗

PubMed1999

Evaluation of cycling patterns of dissolved oxygen in a tropical lake as an indicator of biodegradable organic pollution.

Dissolved oxygen cycling patterns in a tropical lake (Weija Lake) were shown to be useful as a potential indicator of biodegradable organic pollution, by dosing with liquid malt to give an additional organic burden of 2.5 and 5.0 mg l-1 TOC, and monitoring the DO values continuously for 140 h. These loadings were added to water columns (in tubes) suspended from a raft in a lake in south-east Ghana. The addition of organic pollution burden to the lake water produced two main effects: the mean DO value was lowered, and the amplitude of the DO cycle decreased as organic loading increased from 2.5 to 5.0 mg l-1 TOC. There was also an indication of heterotrophic respiration associated with organic inputs for the 5.0 mg l-1 added TOC suggesting a P/R ratio of well below 1.0. Taking the results of a DO cycling computer model together with those from the lake raft experiments, it can be concluded that dissolved oxygen cycles can be a good indicator of biodegradable organic pollution load.

Biodegradation, Environmental↗

PubMed1994

Use of biodegradable mesh as a transport for a cultured uroepithelial graft: an improved method using collagen gel.

OBJECTIVES: To create an improved delivery vehicle for cultured uroepithelial cells using biodegradable mesh and collagen gel. METHODS: Twenty uroepithelial grafts were prepared by seeding cultured urothelial cells onto previously prepared collagen gel-polyglactin mesh. As a control, cells were seeded onto 20 plain polyglactin mesh (without gel) squares in the same fashion. RESULTS: The presence of urothelial cells was confirmed in all cultures by immunohistochemistry testing with anticytokeratin antibody. After 5 to 7 days, a confluent monolayer of cells covered 90% to 100% of the surface of all 20 collagen gel-mesh grafts. A confluent monolayer of cells did not form on any control graft (plain mesh). After 3 weeks, the cells had formed a sporadic, multiple cell layer confluence over 10% to 50% of the control graft surface; however, the mesh became friable and fell apart. CONCLUSIONS: By combining collagen gel with a biodegradable mesh scaffold, we created a surgically implantable cultured uroepithelial graft. The production of the collagen gel-mesh vehicle is simple and inexpensive. With this technique, the use of cultured urothelium for reconstructive urologic surgery can be investigated in greater detail.

Animals↗

PubMed1998

Biodegradation of triphenylmethane dyes.

Biodegradation of triphenylmethane dyes by bacteria, actinomycetes, yeasts, and fungi are discussed in detail. The disadvantages of physical and chemical treatment processes of dye wastewater are also discussed. Biological treatment processes have many advantages over the chemical and physical treatment processes such as possibility of degradation of dye molecules to carbon dioxide and water and formation of less sludge in addition to being environmentally friendly. This group of dyes is toxic depending on the concentration used. Toxicity of triphenylmethane dyes is discussed with respect to different organisms. Some aspects of biodegradative products of this group of dyes are also mentioned.

Bacteria↗

PubMed2000

Synthetic biodegradable polymers as orthopedic devices.

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

Biocompatible Materials↗

PubMed2000

Injectable biodegradable polymer composites based on poly(propylene fumarate) crosslinked with poly(ethylene glycol)-dimethacrylate.

New injectable, in situ crosslinkable biodegradable polymer composites were investigated consisting of poly(propylene fumarate) (PPF), poly(ethylene glycol)-dimethacrylate (PEG-DMA), and beta-tricalcium phosphate (beta-TCP). We examined the effects of the PEG-DMA/PPF double-bond ratio and beta-TCP content on the crosslinking characteristics of the composites including the maximum crosslinking temperature and the gel point, as well as the properties of the crosslinked composites such as the compressive strength and modulus, and the water-holding capacity. The maximum crosslinking temperature was constant averaging 39.7 degrees C for the composite formulations tested. The gel points varied from 8.0 +/- 1.0 to 12.6 +/- 2.5 min and were not affected by the relative amounts of PEG-DMA. The compressive strength at yield of PEG-DMA/PPF composites without beta-TCP increased from 5.9 +/- 1.0 to 11.2 +/- 2.2 MPa as the double-bond ratio of PEG-DMA/PPF increased from 0.38 to 1.88. An increase in compressive modulus was also observed from 30.2 +/- 3.5 to 58.4 +/- 6.2 MPa for the same range of the PEG-DMA/PPF double-bond ratio. Also, the addition of beta-TCP (33 wt%) enhanced the mechanical properties of all composites. The equilibrium water content of networks without beta-TCP increased from 21.7 +/- 0.2 to 30.6 +/- 0.2% for a double-bond ratio of PEG-DMA/PPF ranging from 0.38 to 1.88. However, the mechanical properties of the swollen composites under compression were smaller than the dry ones. These data demonstrate the feasibility of fabricating injectable biodegradable polymer composites with engineered mechanical properties for orthopedic tissue engineering.

Acrylates↗

PubMed2000

Injectable biodegradable materials for orthopedic tissue engineering.

The large number of orthopedic procedures performed each year, including many performed arthroscopically, have led to great interest in injectable biodegradable materials for regeneration of bone and cartilage. A variety of materials have been developed for these applications, including ceramics, naturally derived substances and synthetic polymers. These materials demonstrate overall biocompatibility and appropriate mechanical properties, as well as promote tissue formation, thus providing an important step towards minimally invasive orthopedic procedures. This review provides a comparison of these materials based on mechanical properties, biocompatibility and regeneration efficacy. Advantages and disadvantages of each material are explained and design criteria for injectable biodegradable systems are provided.

Animals↗

PubMed2001

Retinal pigment epithelial cell adhesion on novel micropatterned surfaces fabricated from synthetic biodegradable polymers.

Novel synthetic biodegradable polymer substrates with specific chemical micropatterns were fabricated from poly(DL-lactic-coglycolic acid) (PLGA) and diblock copolymers of poly(ethylene glycol) and poly(DL-lactic acid) (PEG/PLA). Thin films of PLGA and PEG/PLA supported and inhibited, respectively, retinal pigment epithelial (RPE) cell proliferation, with a corresponding cell density of 352,900 and 850 cells/cm2 after 7 days (from an initial seeding density of 15,000 cells/cm2). A microcontact printing technique was used to define arrays of circular (diameter of 50 microm) PLGA domains surrounded and separated by regions (width of 50 microm) of PEG/PLA. Reversed patterns composed of PEG/PLA circular domains surrounded by PLGA regions were also fabricated. Both micropatterned surfaces were shown to affect initial RPE cell attachment, limit cell spreading, and promote the characteristic cuboidal cell morphology during the 8-h period of the experiments. In contrast, RPE cells on plain PLGA (control films) were elongated and appeared fibroblast-like. The reversed patterns had continuous PLGA regions that allowed cell-cell interactions and thus higher cell adhesion. These results demonstrate the feasibility of fabricating micropatterned synthetic biodegradable polymer surfaces to control RPE cell morphology.

Biodegradation, Environmental↗