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PubMed2005

Naphthenic acids in athabasca oil sands tailings waters are less biodegradable than commercial naphthenic acids.

Naphthenic acids (NAs) are natural constituents in many petroleum sources, including bitumen in the oil sands of Northern Alberta, Canada. Bitumen extraction processes produce tailings waters that cannot be discharged to the environment because NAs are acutely toxic to aquatic species. However, aerobic biodegradation reduces the toxic character of NAs. In this study, four commercial NAs and the NAs in two oil sands tailings waters were characterized by gas chromatography-mass spectrometry. These NAs were also incubated with microorganisms in the tailings waters under aerobic, laboratory conditions. The NAs in the commercial preparations had lower molecular masses than the NAs in the tailings waters. The commercial NAs were biodegraded within 14 days, but only about 25% of the NAs native to the tailings waters were removed after 40-49 days. These results show that low molecular mass NAs (C < or =17) are more readily biodegraded than high molecular mass NAs (C > or =18). Moreover, the results indicate that biodegradation studies using commercial NAs alone will not accurately reflect the potential biodegradability of NAs in the oil sands tailings waters.

Alberta↗

PubMed1998

19F NMR study on the biodegradation of fluorophenols by various Rhodococcus species.

Of all NMR observable isotopes 19F is the one perhaps most convenient for studies on biodegradation of environmental pollutants. The reasons underlying this potential of 19F NMR are discussed and illustrated on the basis of a study on the biodegradation of fluorophenols by four Rhodococcus strains. The results indicate marked differences between the biodegradation pathways of fluorophenols among the various Rhodococcus species. This holds not only for the level and nature of the fluorinated biodegradation pathway intermediates that accumulate, but also for the regioselectivity of the initial hydroxylation step. Several of the Rhodococcus species contain a phenol hydroxylase that catalyses the oxidative defluorination of ortho-fluorinated di- and trifluorophenols. Furthermore, it is illustrated how the 19F NMR technique can be used as a tool in the process of identification of an accumulated unknown metabolite, in this case most likely 5-fluoromaleylacetate. Altogether, the 19F NMR technique proved valid to obtain detailed information on the microbial biodegradation pathways of fluorinated organics, but also to provide information on the specificity of enzymes generally considered unstable and, for this reason, not much studied so far.

Biodegradation, Environmental↗

PubMed2000

Viscosity properties of mineral paraffinic base oils as a key factor in their primary biodegradability.

The primary biodegradability of two types of paraffinic base oils (solvent and catalytically dewaxed oils) and their blends was evaluated using the CEC L-33-A-93 test. The biodegradability values varied between 10% and 75%. Base oil mixtures displayed varying contents in aromatic and polar compounds and a wide range of kinematic viscosity (KV) values, from roughly 10 to 600 cSt (at 40 degrees C), while their viscosity indices were almost constant (90-100). The biodegradability of oils was closely related to their content in polycyclic aromatic hydrocarbons and was also decreasing with kinematic viscosity. For the two types of base oils, a linear relationship could be set between the biodegradation percentages and the logarithms of KV values. These results show that, beside overall chemical features such as the contents in aromatic compounds, KV may be a prominent parameter for assessing the primary biodegradability of mineral base oils.

Biodegradation, Environmental↗

PubMed2001

Biodegradation of oil in uplifted basins prevented by deep-burial sterilization.

Biodegradation of crude oil by bacterial activity--which has occurred in the majority of the Earth's oil reserves--is known to reduce greatly the quality of petroleum in reservoirs. For economically successful prospecting for oil, it is therefore important to understand the processes and conditions in geological formations that lead to oil biodegradation. Although recent studies speculate that bacterial activity can potentially occur up to temperatures as high as 150 degrees C (refs 3, 4), it is generally accepted that effective petroleum biodegradation over geological timescales generally occurs in reservoirs with temperatures below 80 degrees C (ref. 2). This appears, however, to be at odds with the observation that non-degraded oils can still be found in reservoirs below this temperature. Here we compile data regarding the extent of oil biodegradation in several oil reservoirs, and find that the extensive occurrence of non-biodegraded oil in shallow, cool basins is restricted to those that have been uplifted from deeper, hotter regions of the Earth. We suggest that these petroleum reservoirs were sterilized by heating to a temperature around 80-90 degrees C during deep burial, inactivating hydrocarbon-degrading organisms that occur in the deep biosphere. Even when such reservoirs are subsequently uplifted to much cooler regions and filled with oil, degradation does not occur, implying that the sterilized sediments are not recolonized by hydrocarbon-degrading bacteria.

Bacteria↗

PubMed2004

Anaerobic hydrocarbon biodegradation in deep subsurface oil reservoirs.

Biodegradation of crude oil in subsurface petroleum reservoirs is an important alteration process with major economic consequences. Aerobic degradation of petroleum hydrocarbons at the surface is well documented and it has long been thought that the flow of oxygen- and nutrient-bearing meteoric waters into reservoirs was necessary for in-reservoir petroleum biodegradation. The occurrence of biodegraded oils in reservoirs where aerobic conditions are unlikely, together with the identification of several anaerobic microorganisms in oil fields and the discovery of anaerobic hydrocarbon biodegradation mechanisms, suggests that anaerobic degradation processes could also be responsible. The extent of anaerobic hydrocarbon degradation processes in the world's deep petroleum reservoirs, however, remains strongly contested. Moreover, no organism has yet been isolated that has been shown to degrade hydrocarbons under the conditions found in deep petroleum reservoirs. Here we report the isolation of metabolites indicative of anaerobic hydrocarbon degradation from a large fraction of 77 degraded oil samples from both marine and lacustrine sources from around the world, including the volumetrically important Canadian tar sands. Our results therefore suggest that anaerobic hydrocarbon degradation is a common process in biodegraded subsurface oil reservoirs.

Aerobiosis↗

PubMed1996

Biodegradation studies of selected hydrocarbons from diesel oil.

In-vitro biodegradation of aliphatic and aromatic hydrocarbons present in diesel oil by Pseudomonas fluorescens, Texaco was studied in an aqueous medium. Small aliquots of diesel oil and its aromatic fraction were incubated aerobically for periods of up to seven months and analysed by GC-MS. Biotic losses proved to be greater for aliphatic than aromatic compounds. Most biodegradation occurred within the first 20 d of incubation. The most rapid biodegradation, up to 65% in 8 d, was observed for n-alkanes (C14-C18). The same compounds were also shown to be less affected by abiotic losses. Biodegradation of n-alkanes from diesel oil and diesel oil itself showed first order kinetics for the initial incubation period. Aromatic compounds proved to be resistant to biodegradation and only phenanthrene had been degraded (30%) within 6 months.

Biodegradation, Environmental↗

PubMed2002

Histologic changes of nonbiodegradable and biodegradable biomaterials used to repair right ventricular heart defects in rats.

OBJECTIVES: Nonbiodegradable synthetic materials have been widely used to repair cardiac defects. Material-related failures, however, such as lack of growth, thrombosis, and infection, do occur. Because a biodegradable scaffold can be replaced by the patient's own cells and will be treated as a foreign body for a limited period, we compared four biodegradable materials (gelatin, polyglycolic acid (PGA), and copolymer made of epsilon-caprolactone and l-lactic acid reinforced with a poly-l-lactide knitted [KN-PCLA] or woven fabric [WV-PCLA]) with a nonbiodegradable polytetrafluoroethylene (PTFE) material. An animal heart model was tested that simulates the in vivo clinical condition to which a synthetic material would be used. METHODS: The five patches were used to repair transmural defects surgically created in the right ventricular outflow tracts of adult rat hearts (n = 5, each patch group). The PTFE patch group served as a control group. At 8 weeks after implantation, the biomaterials were excised. Patch size, patch thickness, infiltrated cell number, extracellular matrix composition, and patch degradation were evaluated. RESULTS: The PTFE patch itself did not change in size except for increasing in thickness because of fibroblast and collagen coverage of both its surfaces. Host cells did not migrate into the PTFE biomaterial. In contrast, cells migrated into the biodegrading gelatin, PGA, and KN-PCLA and WV-PCLA scaffolds. Cellular ingrowth per unit patch area was highest in the KN-PCLA patch. The KN-PCLA patch increased modestly in size and thinness. The WV-PCNA patch did not change in size or thickness. Fibroblasts and collagen were the dominant cellular infiltrate and extracellular matrix formed in the biodegrading scaffolds. The in vivo rates of biomaterial degradation, thinning, and expansion were material specific. All the subendocardial patch surfaces were covered with endothelial cells. No thrombi were seen. CONCLUSIONS: The unique, spongy matrix structure of the PCLA patch favored cell colonization relative to the other patches. The strong, durable outer poly-l-lactide fabric layers in these patches offered physical, biocompatible, and bioresorbable advantages relative to the other biodegradable materials studied. Host cells migrated into all the biomaterials. The cells secreted matrix and formed tissue, which was endothelialized on the endocardial surface. The biomaterial degradation rates and the tissue formation rates were material related. The PCLA grafts hold promise to become a suitable patch for surgical repair.

Absorbable Implants↗

PubMed2001

Biodegradation of isopropanol in a three phase fixed bed bioreactor: start up and acclimation using a previously-enriched microbial culture.

The aerobic biodegradation of high liquid phase concentrations of 2-propanol (IPA) by a previously enriched solvent-tolerant bacterial consortium within a 1.9 l fed-batch three phase fixed bed bioreactor was investigated. Solvent concentrations of up to 7.9 g l(-1) were investigated. Previously enriched solvent-tolerant bacterial cells were immobilised onto porous glass cylinders as a means obioprocess intensification. Bioreactor start-up and acclimation was studied anacetone concentration tracked as an indicator of IPA utilization, as the sole carbon source within a minimal salts medium (MSM). The initial batch treatment of IPA exhibited a biodegradation rate of 0.11 g l(-1) h(-1) prior to biofilm formation Biofilm growth during the second batch treatment was consistent with an increase in metabolic activity and an IPA biodegradation rate of 0.34 g l(-1), followed by a reduction of biodegradation rate to a constant value of 0.078 g l(-1) h(-1) after 650 h. A maximum acetone generation rate of 1.3 g l(-1) h(-1) was obtained during the fourth IPA addition although the maximum acetone biodegradation rate of 0.38 g l(-1) h(-1) was observed during the initial IPA addition. It is proposed that the metabolic lag resulting from switching from alcohol dehydrogenase to acetone carboxylase is a major rate-limiting step in the deep oxidation of IPA to acetone. The results demonstrate the potential of a previously enriched solvent-tolerant bacterial consortium in fixed bed bioreactor systems, for the aerobic treatment of concentrated solvent-containing wastestreams.

2-Propanol↗

PubMed2001

Sorption and biodegradation of vapor-phase organic compounds with wastewater sludge and food waste compost.

To test the possible use of composted food waste and wastewater sludge as biofilters to treat gas-phase volatile organic compounds (VOCs), batch experiments were conducted with an isolated strain that could degrade aromatic compounds under aerobic conditions. A benzene and trichloroethylene (TCE) mixture was used as the gas-phase pollutant in experiments with composted food waste, sludge, and soil. Under aerobic conditions, benzene was degraded as a primary substrate and TCE was degraded cometabolically, with water contents varying from 6 to 60% (volume of water added/volume of solid). Optimal water content for VOC removal was 12% for the soil, 36% for the composted food waste, and 48% for the sludge. The extent of VOC sorption and biodegradation at the optimal water content was different for each material. With the same initial VOC concentration, more VOCs were removed by sorption onto the composted food waste and the sludge, while less VOCs were biodegraded in comparison with the results using soil. The reason the biodegradation in the soil was greater may be partly attributed to the fact that, due to less sorption, the aqueous-phase concentration of VOCs, which microorganisms could utilize as a carbon source or cometabolize, was higher. We also speculate that the distribution of microorganisms in each medium affects the rate of biodegradation. A large number of microorganisms were attached to the composted food waste and sludge. Mass transfer of VOCs and oxygen to these microorganisms, which appear to have been heterogeneously distributed in clusters, may have been limited, resulting in hindered biodegradation.

Adsorption↗

PubMedDate not supplied

Quantitative prediction of biodegradability, metabolite distribution and toxicity of stable metabolites.

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.

Animals↗

PubMed2006

Effect of perozonation on biodegradability and toxicity of a penicillin formulation effluent.

The pretreatment of synthetic penicillin formulation effluent containing Procain Penicillin G (PPG) with the O(3)/H(2)O(2) process (applied ozone dose = 1440 mg h-1 treatment time = 60 minutes; pH 7; H(2)O(2) = 10 mM) was investigated. The effect of chemical pretreatment was assessed on the basis of acute toxicity and biodegradability with activated sludge using water flea Daphnia magna toxicity and activated sludge inhibition tests. Biological treatability studies were performed with a mixture of untreated or pretreated PPG effluent (25% on volume basis) and synthetic domestic wastewater simulating readily biodegradable organic substrate to simulate the characteristics of domestic wastewater (75% on volume basis). Pretreatment of PPG effluent the O(3)/H(2)O(2) process resulted in more than 70% chemical oxygen demand (COD) removal and a 50% decrease in the acute toxicity towards Daphnia magna. On the other hand, biodegradation of untreated PPG effluent needed prolonged acclimation periods to obtain a significant biological COD removal (= 80%). Pretreatment employing the O(3)/H(2)O(2) process not only decreased the ultimate biodegradability of PPG effluent but also increased its inhibitory effects on activated sludge treatment speculatively due to the formation of less biodegradable oxidation by-products.

Animals↗

PubMed2003

Anaerobic biodegradability and treatment of Egyptian domestic sewage.

The anaerobic biodegradability of domestic sewage for four Egyptian villages and four Egyptian cities was determined in batch experiments. The results showed that the biodegradability of the Egyptian-villages sewage (73%) was higher than that of the cities (66%). The higher biodegradability of the soluble COD of village sewage (69%) as compared to that of the cities (46%) was the reason for the higher biodegradability of the total COD of the villages sewage. The biodegradability of suspended COD was similar for the sewage of both villages and cities (73-74%). The results of a mathematical-model. developed based on anaerobic digestion model number 1, indicate that at applying a UASB reactor for the treatment of Egyptian villages and cities sewage, an optimum HRT of, respectively. 16 and 8 h is required. At these HRTs, a total COD removal and a conversion to methane of, respectively, 62-70% and 59-64% can be achieved for the sewage of cities and, respectively, 71-77% and 67-69% for the villages sewage. The model results also show that in the treatment of villages sewage in a two-step (anaerobic filter + UASB reactor) system a higher total COD removal can be obtained (77-81%) at a short HRT of 10 h (4 + 6 h). However, the excess sludge from the first-step of the two-step system will be less stabilized.

Bacteria, Anaerobic↗

PubMed1994

SDS-degrading bacteria attach to riverine sediment in response to the surfactant or its primary biodegradation product dodecan-1-ol.

A laboratory-scale river microcosm was used to investigate the effect of the anionic surfactant sodium dodecyl sulphate (SDS) on the attachment of five Pseudomonas strains to natural river-sediment surfaces. Three of the Pseudomonas strains were chosen for their known ability to express alkylsulphatase enzymes capable of hydrolysing SDS, and the other two for their lack of such enzymes. One strain from each category was isolated from the indigenous bacterial population present in the river sediment used; other isolates were from soil or sewage. The alkylsulphatase phenotypes were confirmed by gel zymography of cell extracts. Addition of SDS to mixed suspensions of river sediment with any one of the biodegradation-competent strains stimulated the attachment of bacteria to the sediment particles. In contrast, the attachment of biodegradation-incompetent strains was weak and, moreover, was unaffected by SDS. The SDS-stimulated attachment for competent organisms coincided with rapid biodegradation of the surfactant. The primary intermediate of SDS biodegradation, dodecan-1-ol, accumulated transiently, and the numbers of attached bacteria correlated closely with the amount of dodecan-1-ol present. Direct addition of dodecan-1-ol also stimulated attachment but the effect was more immediate compared with SDS, when there was a lag period of approximately 2 h. To account for these observations, a model is proposed in which SDS stimulates the attachment of biodegradation-competent bacteria through its conversion to dodecan-1-ol, and it is hypothesized that the observed reversibility of the attachment is due to the subsequent removal of dodecan-1-ol by further bacterial metabolism.

Bacterial Adhesion↗

PubMed2006

Biodegradation of benzo(a)pyrene by a newly isolated Fusarium sp.

Benzo(a)pyrene (BaP) is a five-ring polycyclic aromatic hydrocarbon produced by the incomplete combustion of organic materials. It is one of the priority pollutants listed by the US Environmental Protection Agency. This study describes a fungal isolate that is able to biodegrade benzo(a)pyrene. The filamentous fungus, isolated from leaves of Pterocarpus macrocarpus Kurz., was identified as a Fusarium sp. (strain E033). Fusarium sp. E033 was able to survive in the presence of benzo(a)pyrene concentrations up to 1.2 mM (300 mg L(-1)). Biodegradation experiments using 0.4 mM (100 mg L(-1)) benzo(a)pyrene demonstrated that Fusarium sp. E033 was able to degrade 65-70% of the initial benzo(a)pyrene provided, and two transformation products, a dihydroxy dihydro-benzo(a)pyrene and a benzo(a)pyrene-quinone, were detected within 30 days of incubation at 32 degrees C. The factors affecting biodegradation efficiency were also investigated. While increasing aeration promoted better fungal growth and benzo(a)pyrene biodegradation, increasing the glucose concentration from 5 to 50 mM had an adverse effect on biodegradation. Ethanol and methanol, provided at 5 mM to increase benzo(a)pyrene water solubility, increased the fungal biomass yield but did not promote degradation. The Fusarium sp. E033 isolated in this study can tolerate and degrade relatively high concentrations of benzo(a)pyrene, suggesting its potential application in benzo(a)pyrene bioremediation.

Benzo(a)pyrene↗

PubMed1997

Guided tissue regeneration with non-resorbable and biodegradable barriers: 6 months results.

The aim of the present study was to compare the effects of guided tissue regeneration (GTR) with non-resorbable (ePTFE [G]) and biodegradable barriers (Polyglactin 910 (V)). In 20 patients, providing 25 pairs of symmetrical periodontal defects (7 pairs of interproximal intrabony lesions, 12 pairs of degree II and 6 pairs of degree III furcation involvement), each defect was randomly assigned to treatment with either non-resorbable (control) or biodegradable (test) devices. At baseline and 6 months after surgery, clinical measurements (GI, PPD, PAL-V, PAL-H, P1I) and standardized radiographs were obtained. On the radiographs, the linear distances from the cemento-enamel junction (CEJ) to the alveolar crest (AC), and from the CEJ to bottom of the bony defect (BD) were measured using a computer-assisted analysing method (LMSRT). Both treatments revealed a significant (p < 0.05) PPD reduction (-2.90 +/- 1.33 mm (V), -2.71 +/- 1.41 mm (G)), PAL-V gain (1.78 +/- 1.27 mm (V), 1.46 +/- 1.35 mm (G)), PAL-H gain (2.00 +/- 0.82 mm (V), 1.60 +/- 0.59 mm (G)), and radiographic changes (CEJ-AC: 0.48 +/- 0.75 mm (V), 0.73 +/- 0.92 mm (G); CEJ-BD: -0.76 +/- 0.79 mm (V), -0.41 +/- 0.72 mm (G)) after 6 months. The mean differences between the changes for test and control were not significant for most clinical and radiographic parameters. Similar clinical and radiographic results were found 6 months after surgical treatment using either non-resorbable or biodegradable barriers. More favorable results concerning PAL-H gain could be observed with biodegradable barriers after 6 months. Therefore, based on these results, the use of biodegradable barriers in GTR may be recommended and, thereby, a surgical re-entry to remove non-resorbable barriers can be avoided.

Adult↗

PubMed1998

Regenerative periodontal surgery with non-resorbable and biodegradable barriers: results after 24 months.

The aim of the present study was to compare the effects of guided tissue regeneration (GTR) with non-resorbable (ePTFE) and biodegradable barriers (Polyglactin 910). 23 patients provided 29 pairs of similar contralateral periodontal defects (12 pairs of interproximal intrabony lesions, 11 pairs of degree II and 6 pairs of degree III furcation defects). Each defect was randomly assigned to treatment with either non-resorbable (control [c]) or biodegradable (test [t]) devices. At baseline, 6, 12, 18, and 24 months after surgery, clinical measurements (PlI, GI, PPD, PAL-V, PAL-H) were performed. Standardized radiographs were obtained at baseline 12 and 24 months postsurgically. On the radiographs, the linear distances from the cemento-enamel junction (CEJ) to the alveolar crest (AC) and from the CEJ to bottom of the bony defect (BD) were measured using a computer-assisted analysing method (LMSRT). Both treatments revealed a significant (p<0.05) PPD reduction [all defects: -2.97 +/- 1.90 mm (t), -2.21 +/- 1.73 mm (c); intrabony defects: -4.00 +/- 1.96 mm (t), -3.00 +/- 1.87 mm (c); degree II furcations: -2.67 +/- 0.97 mm (t), -2.08 +/- 1.54 mm (c)], PAL-V gain [all defects: 2.02 +/- 1.83 mm (t), 1.18 mm +/- 1.50 (c); intrabony defects: 3.45 +/- 1.48 mm (t), 1.95 +/- 1.64 mm (c); degree II furcations: 1.33 +/- 0.94 mm (t), 0.92 +/- 1.47 mm (c)], PAL-H gain [degree II furcations: 2.22 +/- 0.94 mm (t), 1.86 +/- 0.60 mm (c)], and radiographic changes [CEJ-AC: -0.56 +/- 1.98 mm (t), -0.06 +/- 1.19 mm (c); CEJ-BD: 2.10 +/- 1.92 mm (t), 1.24 +/- 2.04 mm (c)] after 24 months. For degree III furcations, neither statistically significant PPD reduction nor PAL-V gain was observed. Similar clinical and radiographic results were found 12 and 24 months after surgical treatment using either non-resorbable or biodegradable barriers. More favorable results concerning PAL-V gain in interproximal intrabony defects could be observed with biodegradable barriers after 24 months than using nonresorbable membranes. Whereas interproximal intrabony lesions and degree II furcation defects responded favorably to GTR therapy, through-and-through furcations must be looked upon as a contraindication for this regenerative technique. Based on the results of the present study, the use of biodegradable barriers in GTR may be recommended and, thereby, a surgical re-entry to remove nonresorbable barriers can be avoided.

Adult↗

PubMedDate not supplied

Influence of transient flow on contaminant biodegradation.

The rate of biodegradation in contaminated aquifers depends to a large extent on dispersive mixing processes that are now generally accepted to result from spatial variations in the velocity field. It has been shown, however, that transient flow fields can also contribute to dispersive mixing. The influence of transient flow on biodegrading contaminants is particularly important since it can enhance mixing with electron acceptors, further promoting the reactive process. Using numerical simulations, the effect of transient flow on the behavior of a biodegradable contaminant is evaluated here both with respect to the development of apparently large horizontal transverse dispersion and also with respect to enhanced mixing between the substrate (electron donor) and electron acceptor. The numerical model BIO3D, which solves for advective-dispersive transport coupled with Monod-type biodegradation of substrates in the presence of an electron acceptor, was used for the simulations. The model was applied in a two-dimensional plan view mode considering a single substrate. Transient flow fields were found to yield larger apparent transverse dispersion because the longitudinal dispersivity also acts transverse to the mean flow direction. In the reactive case, the transient flow field increases substrate-oxygen mixing, which in turn enhances the overall rate of biodegradation. The results suggest that in the case of moderate changes of flow directions, a steady-state flow field can be justified, thereby avoiding the higher computational costs of a fully transient simulation. The use of a higher transverse horizontal dispersivity in a steady flow field can, under these conditions, adequately forecast plume development.

Biodegradation, Environmental↗

PubMed1993

In situ stimulation of aerobic PCB biodegradation in Hudson River sediments.

A 73-day field study of in situ aerobic biodegradation of polychlorinated biphenyls (PCBs) in the Hudson River shows that indigenous aerobic microorganisms can degrade the lightly chlorinated PCBs present in these sediments. Addition of inorganic nutrients, biphenyl, and oxygen enhanced PCB biodegradation, as indicated both by a 37 to 55 percent loss of PCBs and by the production of chlorobenzoates, intermediates in the PCB biodegradation pathway. Repeated inoculation with a purified PCB-degrading bacterium failed to improve biodegradative activity. Biodegradation was also observed under mixed but unamended conditions, which suggests that this process may occur commonly in river sediments, with implications for PCB fate models and risk assessments.

Aerobiosis↗