Adaptation of Aerobic, Ethene-Assimilating Mycobacterium Strains to Vinyl Chloride as a Growth Substrate

Jin, Yang; Mattes, Timothy E.

doi:10.1021/es8000536

Cited by 42 publications

(70 citation statements)

References 38 publications

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“…The adaptation of strain JS623 to growth on VC occurred reproducibly after an incubation time of approximately 60 days in the case of both ethene-grown and TSAG-grown inocula, which yielded variants JS623-E and JS623-T, respectively (22). Our hypothesis was that VC adaptation was due to a genetic change in one or more of the ethene biodegradation genes.…”

Section: Resultsmentioning

confidence: 90%

“…All other chemicals either were reagent or molecular biology grade. The general-purpose media used were LB (32) for Escherichia coli and 0.1ϫ Trypticase soy glucose (designated 0.1TSG) medium for Mycobacterium strains (22). Growth on gaseous substrates was tested in minimal salts medium (MSM) (7) broths in gas-tight bottles (i.e., sealed with butyl rubber stoppers [Wheaton] and aluminum crimp caps), using 72, 250, or 500 ml medium in 160-ml serum bottles (Wheaton) or 1-or 2-liter modified Erlenmeyer flasks (28), respectively.…”

Section: Methodsmentioning

confidence: 99%

“…Cultures used here included the wild-type ethene-assimilating Mycobacterium strain JS623 (9) and two VC-adapted variants, JS623-T and JS623-E (22). Other strains used include Mycobacterium smegmatis mc 2 155 (34), Nocardioides JS614 (8), and E. coli strains TOP10 (Invitrogen), DH5␣ FЈI q (New England Biolabs), and EPI300 (Epicentre).…”

Section: Methodsmentioning

confidence: 99%

“…This knowledge gap confounds the development of molecular probes specific for VC-assimilating bacteria. Pseudomonas aeruginosa strain DL1 shifted from cometabolism to growth on VC after more than 40 days of incubation (42), while Mycobacterium strains JS622, JS623, JS624, and JS625 took between 55 and 476 days to adapt to VC (22). The VCadapted phenotype in Mycobacterium strains was not lost after growth in nonselective medium, suggesting a genetic change rather than a physiological adaptation (22).…”

mentioning

confidence: 96%

“…Pure cultures of ethene-assimilating bacteria are capable of spontaneously adapting to growth on VC as a carbon source (22,42), but the molecular basis of this phenomenon is not clear. This knowledge gap confounds the development of molecular probes specific for VC-assimilating bacteria.…”

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confidence: 99%

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Association of Missense Mutations in Epoxyalkane Coenzyme M Transferase with Adaptation of Mycobacterium sp. Strain JS623 to Growth on Vinyl Chloride

Jin

Cheung

Coleman

et al. 2010

Appl Environ Microbiol

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Vinyl chloride (VC) is a toxic groundwater pollutant associated with plastic manufacture and chlorinated solvent use. Aerobic bacteria that grow on VC as a carbon and energy source can evolve in the laboratory from bacteria that grow on ethene, but the genetic changes involved are unknown. We investigated VC adaptation in two variants (JS623-E and JS623-T) of the ethene-oxidizing Mycobacterium strain JS623. Missense mutations in the EtnE gene developed at two positions (W243 and R257) in cultures exposed to VC but not in cultures maintained on ethene. Epoxyalkane-coenzyme M transferase (EaCoMT) activities in cell extracts of JS623-E and JS623-T (150 and 645 nmol/min/mg protein, respectively) were higher than that of wild-type JS623 (74 nmol/min/mg protein), and in both variant cultures epoxyethane no longer accumulated during growth on ethene. The heterologous expression of two variant etnE alleles (W243G [etnE1] and R257L [etnE2]) from strain JS623 in Mycobacterium smegmatis showed that they had 42 to 59% higher activities than the wild type. Recombinant JS623 cultures containing mutant EtnE genes cloned in the vector pMV261 adapted to growth on VC more rapidly than the wild-type JS623 strain, with incubation times of 60 days (wild type), 1 day (pMVetnE1), and 35 days (pMVetnE2). The JS623(pMVetnE) culture did not adapt to VC after more than 60 days of incubation. Adaptation to VC in strain JS623 is consistently associated with two particular missense mutations in the etnE gene that lead to higher EaCoMT activity. This is the first report to pinpoint a genetic change associated with the transition from cometabolic to growth-linked VC oxidation in bacteria.Bacteria that biodegrade pollutants are useful for the cleanup of contaminated sites (i.e., bioremediation) and are interesting as models of evolutionary processes (21,38,40). Understanding the molecular genetic and evolutionary basis of biodegradation processes allows improved monitoring and predictions of bacterial activities in situ (39) and promises the development of improved strains and enzymes with increased specific activity (3), increased substrate affinity (16), extended substrate range (3,16,21,37), extended inducer range (30, 31), or constitutive expression (39). Missense mutations in catabolic enzymes or regulatory proteins commonly lead to these changes (43), although other important mechanisms include duplication, deletion, and inversion (38-40).Vinyl chloride (VC) is a common groundwater pollutant (35) and known human carcinogen (24), and it poses a health risk to exposed populations. Although trace amounts (e.g., parts per trillion) of VC have been detected in uncontaminated soil (23), higher concentrations are found only associated with human industry, particularly the manufacture of polyvinylchloride (PVC) plastic and the chlorinated solvents trichloroethene (TCE) and perchloroethene (PCE) (4). Aerobic bacteria that grow on VC as a sole carbon and energy source are diverse, including strains of Mycobacterium (8,17,18), Nocardioides (8), Pseu...

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Section: Resultsmentioning

confidence: 90%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 96%

mentioning

confidence: 99%

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Association of Missense Mutations in Epoxyalkane Coenzyme M Transferase with Adaptation of Mycobacterium sp. Strain JS623 to Growth on Vinyl Chloride

Jin

Cheung

Coleman

et al. 2010

Appl Environ Microbiol

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Assessment and monitoring tools for aerobic bioremediation of vinyl chloride in groundwater

Begley¹,

Hansen

Wells

et al. 2009

Remediation Journal

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Direct aerobic biodegradation of vinyl chloride (VC) offers a remedial solution for persistent vinyl chloride plumes that are not amenable to the anaerobic process of reductive dechlorination because of either prevailing geochemical conditions or the absence of active Dehalococcoidesethenogenes. However, tools are needed to evaluate and optimize aerobic VC bioremediation. This article describes the development and testing of two techniques-a microbiological tool and a molecular tool-for this purpose. Both methods are based on detection of bacteria that can use vinyl chloride and ethene as growth substrates in the presence of oxygen. The microbiological tool is an activity assay that indicates whether bacteria capable of degrading ethene under aerobic conditions are present in a groundwater sample. This activity assay gave positive results in the area of active VC degradation of an aerobic VC bioremediation test site. A rapid semiquantitative genetic assay was also developed. This molecular tool, based on polymerase chain reaction (PCR) detection of a gene involved in the metabolism INTRODUCTIONVinyl chloride (VC), a toxin and known human carcinogen, is a common contaminant in groundwater (Agency for Toxic Substance and Disease Registry, 2006; U.S. Environmental Protection Agency, 2000). It is produced as a daughter product of the anaerobic biodegradation of more highly chlorinated ethenes, such as tetrachloroethene (PCE) and trichloroethene (TCE) (Kielhorn et al., 2000;Smith, 1984). Although these compounds can be anaerobically transformed to the nontoxic product ethene, the process is often incomplete. This leads to VC stall, a condition in which VC concentrations that are low but greater than the regulatory standard, persist in groundwater.At contaminated sites where either geochemical conditions are not appropriate for complete anaerobic biodegradation of chlorinated ethenes or Dehalococcoides ethenogenes bacteria capable of carrying out the transformation to ethene (He et al., 2003) are not present, direct aerobic treatment may be an option. This treatment methodology depends on the presence and activity of any of a wide variety of bacteria (see Exhibit 1) that have (Coleman et al., 2002;Hartmans & De Bont, 1992;Verce et al., 2000Verce et al., , 2001. These bacteria use VC as a carbon and energy source (i.e., an electron donor), in contrast to the anaerobic biodegradation process in which Dehalococcoides use chlorinated ethenes as electron acceptors and an exogenous electron donor must often be added. The bacteria that aerobically degrade VC apparently do so by way of an assimilation pathway for ethene and are referred to as ethenotrophs (Fogel et al., 2005). This is in contrast to biodegradation schemes where VC is not a growth substrate (i.e., cometabolic or anaerobic degradation). Ethenotrophs metabolize ethene and VC by the same pathway, using these compounds as carbon and energy sources for growth. Exhibit 2 shows a simplified scheme of the predicted pathways for VC and ethene metabolism (Coleman & Sp...

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Primers: Functional Genes for Aerobic Chlorinated Hydrocarbon-Degrading Microbes

Coleman

2015

Springer Protocols Handbooks

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Adaptation of Aerobic, Ethene-Assimilating Mycobacterium Strains to Vinyl Chloride as a Growth Substrate

Cited by 42 publications

References 38 publications

Association of Missense Mutations in Epoxyalkane Coenzyme M Transferase with Adaptation of Mycobacterium sp. Strain JS623 to Growth on Vinyl Chloride

Association of Missense Mutations in Epoxyalkane Coenzyme M Transferase with Adaptation of Mycobacterium sp. Strain JS623 to Growth on Vinyl Chloride

Assessment and monitoring tools for aerobic bioremediation of vinyl chloride in groundwater

Primers: Functional Genes for Aerobic Chlorinated Hydrocarbon-Degrading Microbes

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