Discrimination of Multiple Dehalococcoides Strains in a Trichloroethene Enrichment by Quantification of Their Reductive Dehalogenase Genes

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Discrimination of Multiple Dehalococcoides Strains in a Trichloroethene Enrichment by Quantification of Their Reductive Dehalogenase Genes (2006)

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by Victor F. Holmes , Jianzhong He , Patrick K. H. Lee , Lisa Alvarez-cohen

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BibTeX

@MISC{Holmes06discriminationof,
    author = {Victor F. Holmes and Jianzhong He and Patrick K. H. Lee and Lisa Alvarez-cohen},
    title = {Discrimination of Multiple Dehalococcoides Strains in a Trichloroethene Enrichment by Quantification of Their Reductive Dehalogenase Genes},
    year = {2006}
}

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Abstract

While many anaerobic microbial communities are capable of reductively dechlorinating tetrachloroethene (PCE) and trichloroethene (TCE) to dichloroethene (DCE), vinyl chloride (VC), and finally ethene, the accumulation of the highly toxic intermediates, cis-DCE (cDCE) and VC, presents a challenge for bioremediation processes. Members of the genus Dehalococcoides are apparently solely responsible for dechlorination beyond DCE, but isolates of Dehalococcoides each metabolize only a subset of PCE dechlorination intermediates and the interactions among distinct Dehalococcoides strains that result in complete dechlorination are not well understood. Here we apply quantitative PCR to 16S rRNA and reductase gene sequences to discriminate and track Dehalococcoides strains in a TCE enrichment derived from soil taken from the Alameda Naval Air Station (ANAS) using a four-gene plasmid standard. This standard increased experimental accuracy such that 16S rRNA and summed reductase gene copy numbers matched to within 10%. The ANAS culture was found to contain only a single Dehalococcoides 16S rRNA gene sequence, matching that of D. ethenogenes 195, but both the vcrA and tceA reductive dehalogenase genes. Quantities of these two genes in the enrichment summed to the quantity of the Dehalococcoides 16S rRNA gene. Further, between ANAS subcultures enriched on TCE, cDCE, or VC, the relative copy number of the two dehalogenases shifted 14-fold, indicating that the genes are present in two different Dehalococcoides strains. Comparison of cell yields in VC-, cDCE-, and TCE-enriched subcultures

Keyphrases

trichloroethene enrichment reductive dehalogenase gene multiple dehalococcoides strain tce-enriched subculture alameda naval air station distinct dehalococcoides rrna gene different dehalococcoides strain bioremediation process gene sequence vinyl chloride cell yield experimental accuracy tce enrichment pce dechlorination intermediate tcea reductive dehalogenase gene dehalococcoides strain relative copy number genus dehalococcoides rrna gene sequence many anaerobic microbial community toxic intermediate complete dechlorination single dehalococcoides quantitative pcr ana culture reductase gene copy number ana subculture four-gene plasmid standard

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