SEARCH · PubMed Health

Results for “Biodegradation”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,531 records · Page 85Linked to original sources

PubMed2003

[Biodegradation of herbicide pendimethalin by fungi and its characteristics].

Fungi, which can grow on and degrade pendimethalin, were isolated from activated sludge and soil. The biodegradation characterization in vitro was studied. The results showed that pendimethalin could be degraded by fungi, 16 fungi were isolated by enrichment culture, among which, 10 fungi could degrade more than 60% pendimethalin in 5 days in culture fluid. According to the physiological resistance and the capacity to degrade pendimethalin, three fungi were considered as efficiently degrading strains identified as Aspergillus terreus, Monilochaetes and Aspergillus furnigatus. The efficiency of degradation was affected by culture conditions such as pH, temperature, and concentration of cane sugar and pendimethanlin. The results showed that when the additional carbon source was 0.5%-1.0%, pH value was 6-8, and cultivated temperature was 20-30 degrees C, the growth amount of fungi and the degradation rate were enhanced. The fungi grew quickly, and the biodegradation rate was high under pendimethalin concentration being 100 mg.L-1. The removed amount of pendimethalin increased with increasing pendimethalin concentration. The optimal conditions were proposed, which could provide theoretic basis for prevention and control of pesticides pollution.

Aniline Compounds↗

PubMed2003

Fate of effluent organic matter during soil aquifer treatment: biodegradability, chlorine reactivity and genotoxicity.

Hydrophobic acid (HPO-A) and transphilic acid (TPI-A) fractions of dissolved organic matter (DOM) were isolated from a domestic secondary wastewater effluent that was polished via soil aquifer treatment (SAT). Fractions were isolated using XAD resin adsorption chromatography from samples obtained along the vadose zone flowpath at a full-scale basin recharge facility in Tucson, Arizona. Changes in isolate character during SAT were established via biodegradability (batch test), specific ultraviolet light absorbance (SUVA), trihalomethane formation potential (THMFP), and Ames mutagenicity assays. The dissolved organic carbon (DOC) concentration decreased by >90% during SAT. A significant fraction (up to 20%) of isolated post-SAT HPO-A was biodegradable. The (apparent) refractory nature of DOM that survives SAT may be a consequence of low DOC concentration in groundwater as well as the nature of the compounds themselves. Specific THMFP (microg THM per mg DOC) of HPO-A and TPI-A varied little as a consequence of SAT, averaging 52 and 49 microg THM per mg DOC, respectively. The nonbiodegradable fractions of HPO-A and TPI-A exhibited higher reactivities: 89 and 95 microg THM per mg DOC, respectively. Genotoxicity of HPO-A (on a per mass basis) increased after SAT, suggesting that responsible compounds are removed less efficiently than bulk organics during vadose zone transport.

Arizona↗

PubMed2004

[Study on relationship of biodegradable properties of PGLA film in vivo and in vitro].

This experimental study on the biodegradable properties of poly(glycolide-co-lactide)[PGLA] film in vivo and in vitro was aimed to investigate the relationship between in vivo degradation process and in vitro degradation process. First, PGLA film was cut to 1 cm x 1 cm in size. It was put into artificial saliva and PBS solution respectively in vitro, and was implanted into subcutaneous tissue in Wistar rat in vivo. Then the mass loss rate was calculated every week not only for sample in vitro but also in vivo. The molecular weight was measured every two weeks. The results showed that the degradable speed of PGLA was faster in artificial saliva than in PBS solution. The change of molecular weight was earlier than that of mass loss rate. The degradable period in vitro was about 9-10 weeks. The degradable period in vivo was about 8 weeks. The rate of in vivo degradation was 1.33 times faster than that of in vitro. In conclusion, the degradation of PGLA in vitro was mainly a chemical degradation process achieved by hydrolysis of ester bond. The degradation of PGLA in vivo would be affected by stress and by biological factors, thus the degradation process was apparently faster in vivo, but both accorded with the degradation kinetics model of aliphatic polyester. There was some relationship of biodegradation between in vitro and in vivo.

Absorbable Implants↗

PubMed2004

Aerobic biodegradation of 3-chlorophenol in a sequencing batch reactor: effect of cometabolism.

The aim of the present study was to investigate how phenol modifies, through cometabolism, the biodegrading capability of 3-chlorophenol (3-CP) in a sequencing batch reactor seeded with a mixed culture obtained from a domestic sewage treatment plant. Two laboratory-scale SBRs, one fed 3-CP only and the other fed 3-CP and phenol in the same concentration, were seeded with the partially acclimated biomass. The removal capability in both reactors was measured for progressive increases in the feed organic loading. Cometabolism enhanced biodegradation of 3-CP by reducing both the initial lag period and the time required for the complete removal. 700 mg/L 3-CP was demonstrated to be the highest concentration, which could be completely degraded during the active phase (fill plus react) either in the presence or absence of phenol as the growth substrate even though the lag period was shorter when phenol was present. The operating strategy required modification for the complete removal of 800 mg/L 3-CP. An increase in the phenol to 3-CP ratio did, however, improve 3-CP degradation rate.

Animals↗

PubMed2005

The influence of biodegradability of sewer solids for the management of CSOs.

The re-suspension of sediments in combined sewers and the associated pollutants into the bulk water during wet weather flows can cause pollutants to be carried further downstream to receiving waters or discharged via Combined Sewer Overflows (CSO). A typical pollutograph shows the trend of released bulk pollutants with time but does not consider information on the biodegradability of these pollutants. A new prediction methodology based on Oxygen Utilisation Rate (respirometric method) and Erosionmeter (laboratory device replicating in-sewer erosion) experiments is proposed which is able to predict the trends in biodegradability during in-sewer sediment erosion in wet weather conditions. The proposed new prediction methodology is also based on COD fractionation techniques.

Biodegradation, Environmental↗

PubMed2004

Characterization of natural organic matters effect on the biodegradation in the slow sand filter.

This study focuses on the differences in biodegradation of the natural organic matters (NOMs) of p-hydroxy-benzoic acid (PHBA) and 4-hydroxy-3-methoxy-benzoic acid (VA) with slow sand filter (SSF). The PHBA and VA were biologically transformed into another organic matter in the slow sand filtration (SSF) at the start-up period. The dissolved organic carbon (DOC) of PHBA and VA were stabilized at 2 mg/l after 5th day. The SUVA value of PHBA run decreased with higher sand depth and flow rate, and VA run's increased with higher sand depth, but smaller than PHBA run. Therefore, the PHBA promoted the DBPFP (formation potential of disinfection by products), the VA brought higher biodegradation and lower DBPFP.

Bacteria↗

PubMed2001

Evaluation of the intrinsic mtbe biodegradation potential in MTBE-contaminated soils.

MTBE has only recently being used as an octane enhancer in gasoline in Europe and is considered as a more recent groundwater contaminant on this continent. In this study we examined if during the recent contamination history, European MTBE contaminated aquifers had developed MTBE degrading microbial communities. Different MTBE contaminated and non-contaminated aquifers and soils were tested for their intrinsic biodegradation potential. The role of the oxygen concentration, the availability of nutrients and the influence of the presence of a co-contaminant like benzene on the MTBE biodegradation capabilities of the indigenous microorganisms were examined. All studied soil samples showed degradation of benzene under all tested conditions. On the other hand only one aquifer showed the capacity to degrade MTBE as demonstrated by the disappearance of MTBE and the production of TBA, the main degradation product of MTBE.

Biodegradation, Environmental↗

PubMed2005

Anaerobic biodegradability of Tween surfactants used as a carbon source for the microbial reductive dechlorination of hexachlorobenzene.

Three structurally-related, nonionic, polysorbate surfactants (Tween 60, 61, and 65) were used as the sole carbon source to sustain the microbial, sequential reductive dechlorination of hexachlorobenzene (HCB) in a mixed, methanogenic culture derived from a contaminated estuarine sediment. The surfactants were partially degraded and fermented to methane with no measurable accumulation of volatile fatty acids, indicating that methanogenesis was rapid relative to the rates of hydrolysis and acidogenesis. Addition of the methanogenesis inhibitor 2-bromoethanesulfonic acid resulted in acetate accumulation without impact on the sequential dechlorination of HCB. An anaerobic biodegradability assay was performed and the following data were obtained for the Tween 60, 61, and 65, respectively: 53, 62, and 62% COD destruction; 35, 57, and 48% COD to methane conversion; and 38, 38, and 45% COD to acetate conversion. These data suggest that the hydrophobic moiety (stearate) of the surfactants was preferentially degraded, most likely through beta-oxidation, to acetate and ultimately to methane and carbon dioxide. Between 38 and 47% of the initial surfactant COD remained after 46 d incubation, which most likely corresponds to the hydrophilic polyoxyethylene moiety. An anaerobic biodegradation pathway of the Tween surfactants is proposed.

Alkanesulfonic Acids↗

PubMed2005

Aerobic phenanthrene biodegradation in a two-phase partitioning bioreactor.

The aerobic degradation of phenanthrene by a Pseudomonas migulae strain under classical mechanical aeration and under photosynthetic oxygenation (using a Chlorella sorokiniana strain) in a two-phase partitioning bioreactor (TPPB) constructed with silicone oil as organic phase was investigated. When traditional mechanical aeration was used, an increase in the aeration and/or in the agitation rate enhanced phenanthrene biodegradation. Thus, phenanthrene removal rates (based on the total liquid volume of cultivation) ranged from 22 +/- 1 to 36 +/- 2 mg/l h at 100 rpm and 1 vvm and 400 rpm and 3 vvm, respectively. On the other hand, during phenanthrene biodegradation using the algal-bacterial microcosm a maximum rate of 8.1 +/- 1.2 mg/l h at 200 rpm and 8000 lux of illuminance was achieved.

Analysis of Variance↗

PubMed2006

[The research of film formation properties of the aerosol of biodegradable multi-function film].

The aerosol of biodegradable multi-function film were prepared, whose properties, affective factors and hemostasis effect were studied. Film formation properties were investigated in different lots of aerosols, including film formation time, uniformity, film particle size and film thickness. Young's modulus was about 0. 0373GPa, and elongation at break was 0. 89% by means of tensile method. It is proved that the aerosol of biodegradable multi-function film is easy to form films and its hemostasis effect is well.

Aerosols↗

PubMed2006

Biodegradation of hydrocarbon contamination by immobilized bacterial cells.

This study examined the capacity of immobilized bacteria to degrade petroleum hydrocarbons. A mixture of hydrocarbon-degrading bacterial strains was immobilized in alginate and incubated in crude oil-contaminated artificial seawater (ASW). Analysis of hydrocarbon residues following a 30-day incubation period demonstrated that the biodegradation capacity of the microorganisms was not compromised by the immobilization. Removal of n-alkanes was similar in immobilized cells and control cells. To test reusability, the immobilized bacteria were incubated for sequential increments of 30 days. No decline in biodegradation capacity of the immobilized consortium of bacterial cells was noted over its repeated use. We conclude that immobilized hydrocarbon-degrading bacteria represent a promising application in the bioremediation of hydrocarbon-contaminated areas.

Alginates↗

PubMed2006

[Effect of pH value on fermentation pathways of biodegradable organic waste].

Batch reactors were set up to evaluate the effect of pH value on the anaerobic fermentation of biodegradable organic waste. The results show that pH=7 of fermentative media is favorable for the microbial growth and proliferation, thereby promoting hydrolysis and acidogenesis of particulate biodegradable organic waste. The predominant fermentation types are diverse at different pH value, butyric acid fermentation dominates at pH=7, and at the later phase of pH= 8, propionic acid fermentation dominates at the later phase of pH=5. Lactic acid is produced at the early phase of fermentation, but gradually degrades at pH=5 and pH=7, while remains constant at pH=8. The predominant metabolic pathway shifts from alcohol-forming pathway to acid-forming pathway except for pH=5, where alcoholic fermentation still dominates at the later phase. The first-order hydrolysis constants k(h) for pH 5, 7 and 8 are equal to 0.000 8 h(-1), 0.000 9 h(-1) and 0.0002 h(-1), respectively. The soluble total organic carbon is mainly composed of acidogenic products after 100 h, 300 h and 600 h for pH=7, 5 and 8, respectively.

Acetic Acid↗

PubMed2006

[Preparation of aerosol of biodegradable multi-function film and investigation of its properties].

The aerosol of biodegradable multi-function film was prepared by means of two-step methods, and its properties were investigated. The average loading capacity was 4.8603 g; the average leaking rate was 3.03% per year which was less than 5%. And the average ejecting rate was 0.7380 g/s. The results demonstrate that the aerosol of biodegradable multi-function film has met the principles governing the quality of the aerosols.

Aerosols↗

PubMedDate not supplied

[Catalysis of the biodegradation of unusable medicines by alkanotrophic rhodococci].

Experiments on the biodegradation of unusable medicines containing a phenolic hydroxy group by actinobacteria of the genus Rhodococcus were performed. Six species and sixty-four strains were tested. It was found that rhodococci could degrade paracetamol, and some R. ruber strains showed high levels of its degradation. An efficient method for the identification and quantification of paracetamol and the products of its conversion (p-aminophenol, pyrocatechol, and hydroquinone) immediately in the culture liquid was developed. Conditions for the complete biodegradation of paracetamol dosage forms (pills) were optimized. The experimental results can be applied for the development of biotechnological methods for degrading medicines: faked, rejected, or those that are expired.

Acetaminophen↗

PubMedDate not supplied

Petroleum asphaltenes: generated problematic and possible biodegradation mechanisms.

Petroleum asphaltenes are hydrocarbons that present an extremely complex molecular structure. They are conformed by different proportions of nitrogen, sulfur and oxygen. These compounds cause diverse problems like the blockage of crude oil extraction and transport pipes, the reduction of their economic use and the pollution of ecosystems. Biodegradation of asphaltenes is an important process that can eliminate these compounds and reduce the problems they cause. However, it is a process that occurs naturally in very reduced proportions. The purpose of this revision is to show the chemical structure of these compounds, the problems they cause and to represent their possible biodegradation mechanisms, based on the processes known for other hydrocarbons of complex structure. Elimination of the micelar structure, through the application of non-polar solvents, and fragmentation of the asphaltenes through photooxidation are the initial processes necessary to be able to degrade these compounds. The produced structures, such as the heteropolyaromatic and aromatic, lineal and ramified hydrocarbons, could be degraded in this order through biochemical reactions, such as omega oxidations, beta oxidations and aromatic oxidations respectively. These processes are distributed in an important variety of microorganisms. The elimination period's length can vary from one week, for the simplest structures, to 990 days for those with several condensed aromatic rings.

Bacteria↗

PubMed2006

[Biodegradation of benzene series compounds under nitrate reducing conditions].

A series of batch experiments were performed using mixed bacterial culture to investigate the biodegradability of benzene, toluene, ethylbenzene and the xylene isomers (BTEX) under denitrifying conditions. The results show that BTEX can be degraded effectively by the mixed bacterial culture. The biodegradation of BTEX could be modeled by the substrate inhibition Monod equation. When the concentrations of BTEX were less than 50 mg x L(-1), the anaerobic degradation rates decreased with toluene > ethylbenzene > m-xylene > o-xylene > p-xylene > benzene. The ratio between the amount of nitrate consumed and the amount of the benzene, toluene, ethylbenzene, o-xylene, m-xylene, p-xylene degraded was 9.47, 9.26, 11.14, 12.46, 13.36 and 13.02, respectively. The electron acceptor needed in the initial anaerobic degradation of BTEX was nitrate, and then both nitrate and nitrite could be served as the electron acceptors for the further degradation of the intermediates of BTEX.

Bacteria, Anaerobic↗

PubMed1991

Microspheres of biodegradable polymers as a drug-delivery system in the vitreous.

Microspheres of biodegradable polymers were evaluated as a potential controlled-release drug-delivery system in the vitreous. The microspheres were prepared with polymers of poly(lactic acid) or copolymers of glycolic acid and lactic acid. The release of 5-fluorouracil (5-FU) from the microspheres was studied in vitro. Poly(lactic acid) microspheres released 70-85% of total 5-FU over 7 days. Microspheres of polymers with a smaller molecular weight released the drug more rapidly. Copolymer microspheres released 98% of 5-FU over 2 days. The rate of drug release was controllable by changing the molecular weight of the polymers or using a matrix of copolymer. The intravitreal kinetics of the microspheres were studied in ten rabbits in vivo. A suspension of microspheres was injected into the vitreous cavity of five normal eyes and five vitrectomized eyes. By 48 +/- 5.2 days after injection, the microspheres disappeared from the vitreous cavity in the five normal eyes. Clearance from the vitreous cavity was accelerated in the five rabbits that underwent vitrectomy (14 +/- 2.4 days; P less than 0.001). No difference was found in the b waves of electroretinograms before and after injection of the microspheres. The histologic study showed no abnormal findings as a result of the injection. These results suggested that microspheres of biodegradable polymers may be a potential delivery system for the controlled release of drugs in the vitreous.

Animals↗

PubMed1991

Evaluation of biodegradable ampicillin anhydrate microcapsules for local treatment of experimental staphylococcal osteomyelitis.

Successful treatment of chronic osteomyelitis requires sustained high concentrations of antibiotics locally within the infected bone. The efficacy of biodegradable (poly-DL-lactide-co-glycolide) microspheres containing 30.7% ampicillin anhydrate for the local treatment of experimental staphylococcal osteomyelitis was evaluated in rabbits. In the initial experiment, antibiotic therapy was initiated immediately following injection of Staphylococcus aureus into the proximal tibial metaphysis. A single intramedullary injection of microencapsulated ampicillin (100 mg) prevented osteomyelitis in all seven animals tested and was as effective as a two-week course of parenteral ampicillin administration. When antibiotic therapy was delayed for seven days, osteomyelitis developed in four of eight animals treated locally with microencapsulated ampicillin and in six of eight animals that received parenteral ampicillin therapy. When antibiotic therapy was delayed for seven days and was preceded by debridement, all ten animals treated locally with microencapsulated ampicillin had sterile bone cultures. In contrast, seven of ten animals treated locally with unencapsulated ampicillin powder developed osteomyelitis. Biodegradable antibiotic-loaded microspheres may be of clinical benefit for the local treatment of chronic osteomyelitis.

Ampicillin↗