Transition from Cometabolic to Growth-Linked Biodegradation of Vinyl Chloride by a <i>Pseudomonas</i> sp. Isolated on Ethene

Verce, Matthew F.; Ulrich, Ricky L.; Freedman, David L.

doi:10.1021/es002064f

Cited by 76 publications

(101 citation statements)

References 39 publications

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“…There is good evidence in at least one case that VC degraders evolved directly from ethene-degraders-this was observed in vitro with Pseudomonas strain DL1 (34). The transition from ethene to VC assimilation could be due to recruitment of an additional catabolic enzyme (23), changes in enzyme specificity (25), or alteration of enzyme expression levels (31).…”

Section: Resultsmentioning

confidence: 99%

“…EaCoMT genes were not found in BLAST database searches of Mycobacterium genomes (or any other genomes) that have been completed to date, indicating that EaCoMT is specific to the alkene-assimilation pathway. It remains to be determined whether EaCoMT is involved in the VC and ethene assimilation pathways of Pseudomonas (33,34) and Nocardioides (5) strains. The EaCoMT gene primers we have developed could be used to address this question.…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Distribution of the Coenzyme M Pathway of Epoxide Metabolism among Ethene- and Vinyl Chloride-Degrading Mycobacterium Strains

Coleman¹,

Spain²

2003

Appl Environ Microbiol

109

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Aerobic bacteria that grow on ethene and vinyl chloride (VC) are widely distributed in the environment and have attracted interest because of their potential applications in bioremediation and biocatalysis (5,6,11,12,32,33). The first step in ethene and VC assimilation is known to be a monooxygenase reaction yielding epoxyethane from ethene (5, 7) and chlorooxirane from VC (12, 33), but the downstream pathways are not well understood. Our recent work (5a) has revealed that an epoxyalkane:coenzyme M (CoM) transferase (EaCoMT) enzyme is involved in epoxyethane and chlorooxirane metabolism in Mycobacterium strain JS60, a strain isolated from contaminated groundwater by enrichment on VC as the sole carbon source (5). The EaCoMT reaction is a key step that channels the initial intermediates into central metabolic pathways and also guards against the accumulation of highly toxic and reactive epoxides in the cytoplasm.EaCoMT enzymes have previously been found only in the propene-oxidizing bacteria Xanthobacter strain Py2 and Rhodococcus strain B-276. In such strains, EaCoMT is part of an unusual epoxide carboxylase enzyme complex consisting of EaCoMT, two stereoselective dehydrogenases, and an oxidoreductase/carboxylase (1, 2, 9, 16). In addition to unique biochemical reactions, the propene assimilation pathway is also distinguished by unusual genetic elements. In both strains Py2 and B-276, the propene monooxygenase genes are carried on linear megaplasmids, and in strain Py2, the epoxide carboxylase system and CoM biosynthesis genes are also plasmid borne (18,26).As part of the study that yielded strain JS60, we isolated many other mycobacteria that grew on VC (5). It is not known whether these isolates or similar Mycobacterium strains isolated on ethene (6, 7) possess EaCoMT enzymes. The relationship between strains isolated on VC and ethene is unclear, and the role of factors such as site contamination and geography in the dissemination and evolution of both groups is unknown. On the basis of the recent finding that the EaCoMT gene in Xanthobacter Py2 is carried by a linear plasmid, it might be speculated that similar elements are involved in ethene and VC metabolism. To address these questions, we investigated 10 mycobacteria isolated on VC (6 strains) or ethene (4 strains) from a diverse range of environmental samples. EaCoMT genes and enzyme activities were found in all of the strains. In the VC degraders, the EaCoMT enzymes appear to be encoded on linear megaplasmids. MATERIALS AND METHODSIsolation and growth of bacteria. The growth methods and media used were described previously (5, 5a). Six Mycobacterium strains (JS60, JS61, JS616, JS617, JS619, and JS621) that grow on VC and ethene were previously isolated (5) from groundwater (Plaquemine, La.), activated sludge (Ithaca, N.Y.), pond sediment (Carlyss, La.), activated carbon (Dortmund, Germany), aquifer sediment (Travis Air Force Base, Calif.), and groundwater (Moody Air Force Base, Ga.), respectively. Several mycobacteria that grow on ethene (but not VC) wer...

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Distribution of the Coenzyme M Pathway of Epoxide Metabolism among Ethene- and Vinyl Chloride-Degrading Mycobacterium Strains

Coleman¹,

Spain²

2003

Appl Environ Microbiol

109

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“…The ability of cDCE-grown JS666 cells to transform other chloroethenes may prove to be very useful at contaminated sites, where mixtures of pollutants may be encountered (22). It is surprising that strain JS666 did not grow on ethene, which seems to be the most likely natural substrate of the cDCE-degrading enzymes, particularly considering the fact that the VC-assimilating bacteria isolated to date also use ethene as a carbon source (8,26) and at least in one case appear to have evolved directly from ethene-degrading bacteria (27).…”

Section: Resultsmentioning

confidence: 99%

Biodegradation of cis -Dichloroethene as the Sole Carbon Source by a β-Proteobacterium

Coleman

Mattes

Gossett

et al. 2002

Appl Environ Microbiol

197

152

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An aerobic bacterium capable of growth on cis-dichloroethene (cDCE) as a sole carbon and energy source was isolated by enrichment culture. The 16S ribosomal DNA sequence of the isolate (strain JS666) had 97.9% identity to the sequence from Polaromonas vacuolata, indicating that the isolate was a ␤-proteobacterium. At 20°C, strain JS666 grew on cDCE with a minimum doubling time of 73 ؎ 7 h and a growth yield of 6.1 g of protein/mol of cDCE. Chloride analysis indicated that complete dechlorination of cDCE occurred during growth. The half-velocity constant for cDCE transformation was 1.6 ؎ 0.2 M, and the maximum specific substrate utilization rate ranged from 12.6 to 16.8 nmol/min/mg of protein. Resting cells grown on cDCE could transform cDCE, ethene, vinyl chloride, trans-dichloroethene, trichloroethene, and 1,2-dichloroethane. Epoxyethane was produced from ethene by cDCE-grown cells, suggesting that an epoxidation reaction is the first step in cDCE degradation.The extensive use of chloroethenes as solvents and synthetic feedstocks has resulted in widespread environmental contamination (22), which is of concern due to the toxicity and carcinogenicity of such compounds. Microbial metabolism is an important factor in determining the fate of chloroethenes in the biosphere (14). Several anaerobic bacteria use tetrachloroethene (perchloroethene) and trichloroethene (TCE) as electron acceptors, producing cis-1,2-dichloroethene (cDCE), vinyl chloride (VC), and ethene as end products (10,15,16,17). Under aerobic conditions, ethene and VC can serve as carbon and energy sources for bacterial growth (3, 8), but thus far, no conclusive evidence exists for aerobic growth on any of the dichloroethenes (cis-dichloroethene, trans-dichloroetheneBecause cDCE accumulation is often a limiting factor in the biodegradation of chloroethenes in subsurface ecosystems, aerobic bacteria capable of growth on cDCE would provide a crucial missing link in the chain of microbial metabolism for this class of compounds. Thermodynamic calculations suggest that cDCE contains sufficient energy to support aerobic growth (4), and enzymes active on cDCE are known in hydrocarbonoxidizing bacteria (5,6,13,20,24,25). In addition, aerobic oxidation of cDCE to CO 2 has been observed in microcosm and enrichment culture studies (2, 12). Encouraged by the facts described above, we hypothesized that aerobic growth on cDCE was possible and searched at a variety of contaminated sites for microorganisms able to use this compound as a sole source of carbon and energy. MATERIALS AND METHODSChemicals and media. cis-Dichloroethene (97%), tDCE (98%), TCE (99.5%), and 1,2-dichloroethane (1,2-DCA) (99.8%) were obtained from Sigma-Aldrich. VC (99.5%) was obtained from Fluka, and ethene (99.5%) was obtained from Scott. All other chemicals were reagent grade. A minimal salts medium (MSM) based on that of Hartmans et al. (9) was used for enrichment cultures, with the following modifications: the phosphate concentration was reduced to 20 mM, the ammonium concentration was red...

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“…Hence, the reductive dechlorination of chlorinated ethenes is strongly influenced by the local redox conditions. The transformation intermediates can also be oxidized metabolically and cometabolically under oxic and/or anoxic conditions (Wackett and Gibson, 1988;Little et al, 1988;Oldenhuis et al, 1989;Tsien et al, 1989;Nelson et al, 1987;Davis and Carpenter, 1990;Fox et al, 1990;Bradley and Chapelle, 1998;Verce et al, 2001). Since the intermediates, especially VC, have a high toxicity, it is important to know whether complete or only partial transformation is occurring at a site.…”

Section: Introductionmentioning

confidence: 99%

Evaluating the fate of chlorinated ethenes in streambed sediments by combining stable isotope, geochemical and microbial methods

Abe

Aravena

Zopfi

et al. 2009

Journal of Contaminant Hydrology

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a b s t r a c tThe occurrence of chlorinated ethene transformation in a streambed was investigated using concentration and carbon isotope data from water samples taken at different locations and depths within a 15 × 25 m study area across which a tetrachloroethene (PCE) plume discharges. Furthermore, it was evaluated how the degree of transformation is related to groundwater discharge rates, redox conditions, solid organic matter content (SOM) and microbial factors. Groundwater discharge rates were quantified based on streambed temperatures, and redox conditions using concentrations of dissolved redox-sensitive species. The degree of chlorinated ethene transformation was highly variable in space from no transformation to transformation beyond ethene. Complete reductive dechlorination to ethane and ethene occurred at locations with at least sulfate-reducing conditions and with a residence time in the samples streambed zone (80 cm depth) of at least 10 days. Among these locations, Dehalococcoides was detected using a PCR method where SOM contents were N 2% w/w and where transformation proceeded beyond ethene. However, it was not detected at locations with low SOM, which may cause an insufficient H 2 supply to sustain a detectably dense Dehalococcoides population. Additionally, it is possible that other organisms are responsible for the biodegradation. A microcosm study with streambed sediments demonstrated the potential of VC oxidation throughout the site even at locations without a pre-exposure to VC, consistent with the detection of the epoxyalkane:coenzyme M transferase (EaCoMT) gene involved in the degradation of chlorinated ethenes via epoxidation. In contrast, no aerobic transformation of cDCE in microcosms over a period of 1.5 years was observed. In summary, the study demonstrated that carbon isotope analysis is a sensitive tool to identify the degree of chlorinated ethene transformation even in hydrologically and geochemically complex streambed systems. In addition, it was observed that the degree of transformation is related to redox conditions, which in turn depend on groundwater discharge rates.

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Transition from Cometabolic to Growth-Linked Biodegradation of Vinyl Chloride by a Pseudomonas sp. Isolated on Ethene

Cited by 76 publications

References 39 publications

Distribution of the Coenzyme M Pathway of Epoxide Metabolism among Ethene- and Vinyl Chloride-Degrading Mycobacterium Strains

Distribution of the Coenzyme M Pathway of Epoxide Metabolism among Ethene- and Vinyl Chloride-Degrading Mycobacterium Strains

Biodegradation of cis -Dichloroethene as the Sole Carbon Source by a β-Proteobacterium

Evaluating the fate of chlorinated ethenes in streambed sediments by combining stable isotope, geochemical and microbial methods

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