Vinyl Chloride: Still a Cause for Concern

Kielhorn, Janet; Melber, Christine; Wahnschaffe, Ulrich; Aitio, Antero; Mangelsdorf, Inge

doi:10.2307/3434875

Cited by 71 publications

(85 citation statements)

References 48 publications

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“…of H&HS, 2005) that have been widely used for a variety of applications, including dry cleaning and metal degreasing (Mohn and Tiedje, 1992;McCarty, 1997). The partially dechlorinated degradation products of TCE, dichloroethene (cis-DCE and trans-DCE) and VC (vinyl chloride), are also toxic, and VC is a known human carcinogen (Kielhorn et al, 2000;US Dept. of H&HS, 2005).…”

Section: Introductionmentioning

confidence: 99%

Metagenomic analysis of a stable trichloroethene-degrading microbial community

et al. 2012

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Dehalococcoides bacteria are the only organisms known to completely reduce chlorinated ethenes to the harmless product ethene. However, Dehalococcoides dechlorinate these chemicals more effectively and grow more robustly in mixed microbial communities than in isolation. In this study, the phylogenetic composition and gene content of a functionally stable trichloroethene-degrading microbial community was examined using metagenomic sequencing and analysis. For phylogenetic classification, contiguous sequences (contigs) longer than 2500 bp were grouped into classes according to tetranucleotide frequencies and assigned to taxa based on rRNA genes and other phylogenetic marker genes. Classes were identified for Clostridiaceae, Dehalococcoides, Desulfovibrio, Methanobacterium, Methanospirillum, as well as a Spirochete, a Synergistete, and an unknown Deltaproteobacterium. Dehalococcoides contigs were also identified based on sequence similarity to previously sequenced genomes, allowing the identification of 170 kb on contigs shorter than 2500 bp. Examination of metagenome sequences affiliated with Dehalococcoides revealed 406 genes not found in previously sequenced Dehalococcoides genomes, including 9 cobalamin biosynthesis genes related to corrin ring synthesis. This is the first time that a Dehalococcoides strain has been found to possess genes for synthesizing this cofactor critical to reductive dechlorination. Besides Dehalococcoides, several other members of this community appear to have genes for complete or near-complete cobalamin biosynthesis pathways. In all, 17 genes for putative reductive dehalogenases were identified, including 11 novel ones, all associated with Dehalococcoides. Genes for hydrogenase components (271 in total) were widespread, highlighting the importance of hydrogen metabolism in this community. PhyloChip analysis confirmed the stability of this microbial community.

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Section: Introductionmentioning

confidence: 99%

Metagenomic analysis of a stable trichloroethene-degrading microbial community

et al. 2012

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“…Vinyl chloride (VC) is a toxic and carcinogenic priority pollutant that threatens drinking water quality in most industrialized countries (16). Naturally occurring transformation reactions acting on chlorinated solvents such as tetrachloroethene (PCE)andtrichloroethene (TCE), which are abundant groundwater pollutants (25,29,34,36), serve as a major source of environmental VC.…”

mentioning

confidence: 99%

Genetic Identification of a Putative Vinyl Chloride Reductase in Dehalococcoides sp. Strain BAV1

Krajmalnik‐Brown¹,

Hölscher

Thomson

et al. 2004

Appl Environ Microbiol

228

238

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Dehalococcoides sp. strain BAV1 couples growth with the reductive dechlorination of vinyl chloride (VC) to ethene. Degenerate primers targeting conserved regions in reductive dehalogenase (RDase) genes were designed and used to PCR amplify putative RDase genes from strain BAV1. Seven unique RDase gene fragments were identified. Transcription analysis of VC-grown BAV1 cultures suggested that bvcA was involved in VC reductive dechlorination, and the complete sequence of bvcA was obtained. bvcA was absent in Dehalococcoides isolates that failed to respire VC, yet was detected in four of eight VC-respiring mixed cultures.

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“…Monooxygenases, such as liver cytochrome P-450 (16,44), oxidize VC and ethene to highly reactive epoxides that pose potential health risks. Whereas uncertainty exists concerning the dangers of low-level ethene exposure (43), VC is known to be a human carcinogen (23).…”

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confidence: 99%

Epoxyalkane:Coenzyme M Transferase in the Ethene and Vinyl Chloride Biodegradation Pathways of Mycobacterium Strain JS60

2003

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Mycobacterium strains that grow on ethene and vinyl chloride (VC) are widely distributed in the environment and are potentially useful for biocatalysis and bioremediation. The catabolic pathway of alkene assimilation in mycobacteria is not well characterized. It is clear that the initial step is a monooxygenase-mediated epoxidation that produces epoxyethane from ethene and chlorooxirane from VC, but the enzymes involved in subsequent transformation of the epoxides have not been identified. We investigated epoxyethane metabolism in Mycobacterium strain JS60 and discovered a coenzyme M (CoM)-dependent enzyme activity in extracts from VCand ethene-grown cells. PCR amplifications using primers targeted at epoxyalkane:CoM transferase (EaCoMT) genes yielded part of the JS60 EaCoMT gene, which was used to clone an 8.4-kb genomic DNA fragment. The complete EaCoMT gene (etnE) was recovered, along with genes (etnABCD) encoding a fourcomponent monooxygenase and two genes possibly involved in acyl-CoA ester metabolism. Reverse transcription-PCR indicated that the etnE and etnA genes were cotranscribed and inducible by ethene and VC. Heterologous expression of the etnE gene in Mycobacterium smegmatis mc 2 155 using the pMV261 vector gave a recombinant strain capable of transforming epoxyethane, epoxypropane, and chlorooxirane. A metabolite identified by mass spectrometry as 2-hydroxyethyl-CoM was produced from epoxyethane. The results indicate that the EaCoMT and monooxygenase enzymes encoded by a single operon (etnEABCD) catalyze the initial reactions in both the VC and ethene assimilation pathways. CoM-mediated reactions appear to be more widespread in bacteria than was previously believed.

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Vinyl Chloride: Still a Cause for Concern

Cited by 71 publications

References 48 publications

Metagenomic analysis of a stable trichloroethene-degrading microbial community

Metagenomic analysis of a stable trichloroethene-degrading microbial community

Genetic Identification of a Putative Vinyl Chloride Reductase in Dehalococcoides sp. Strain BAV1

Epoxyalkane:Coenzyme M Transferase in the Ethene and Vinyl Chloride Biodegradation Pathways of Mycobacterium Strain JS60

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