Title:
Genetic Identification of Reductive Dehalogenase Genes in Dehalococcoides

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dc.contributor.advisor Löffler, Frank E.
dc.contributor.advisor Saunders, F. Michael
dc.contributor.author Krajmalnik-Brown, Rosa en_US
dc.contributor.committeeMember Wartell, Roger
dc.contributor.committeeMember Zhulin, Igor B.
dc.contributor.committeeMember Huang, Ching-Hua
dc.contributor.department Civil and Environmental Engineering en_US
dc.date.accessioned 2006-09-01T19:45:19Z
dc.date.available 2006-09-01T19:45:19Z
dc.date.issued 2005-07-20 en_US
dc.description.abstract Chloroethenes such as tetrachloroethene (PCE), trichloroethene (TCE), dichloroethene (DCE) and vinyl chloride (VC), are major contaminants in subsurface systems threatening water quality and human health. Under anaerobic conditions, PCE and TCE can be reductively dechlorinated to ethene. Recent findings indicate that members of the Dehalococcoides group are responsible for ethene formation at chloroethene-contaminated sites. Dehalococcoides species exhibit diverse dechlorination activities, but share highly similar 16S rRNA genes. Hence, additional gene targets that go beyond the 16S rRNA gene are needed to reliably detect and quantify Dehalococcoides populations involved in high rate chloroethene detoxification at contaminated sites. Dehalococcoides sp. strain BAV1 couples growth to reductive dechlorination of VC to ethene. To shed light on the genes involved in reductive dechlorination in strain BAV1, degenerate primers targeting reductive dehalogenase (RDase) genes of Dehalococcoides were designed using available sequence information. PCR amplification with these primers yielded seven putative RDase genes with genomic DNA from strain BAV1 as template. Transcription analysis identified one RDase gene possibly involved in VC dechlorination, which was named bvcA. The bvcA gene was not present in Dehalococcoides strains that failed to couple growth with reductive dechlorination of VC (i.e., Dehalococcoides isolates CBDB1, FL2 and 195). Primers specific for bvcA detected this gene in several, but not all, Dehalococcoides-containing, ethene-producing mixed cultures. Apparently, the bvcA-targeted primers do not capture the diversity of VC RDase genes. Nevertheless, a relevant target was identified, and bvcA-targeted primers are commercially applied to monitor Dehalococcoides sp. strain BAV1 and related organisms at contaminated sites undergoing bioremediation treatment. Additional RDase genes were identified in Dehalococcoides sp. strain FL2, and expression analysis was performed when FL2 was grown with cis-DCE and TCE as electron acceptors. Multiple RDase genes were transcribed with each electron acceptor. This work identified novel process-specific target genes that are useful for site assessment and bioremediation monitoring at chloroethene-contaminated sites. In particular, bvcA emerged as a relevant target for monitoring the critical detoxification step from VC, to ethene. Additionally, the RDase genes retrieved in this work form a basis for further exploration of the specific functions and regulation mechanisms involved in reductive dechlorination processes. en_US
dc.description.degree Ph.D. en_US
dc.format.extent 3254904 bytes
dc.format.mimetype application/pdf
dc.identifier.uri http://hdl.handle.net/1853/11642
dc.language.iso en_US
dc.publisher Georgia Institute of Technology en_US
dc.subject Reductive dechlorination
dc.subject Reductive dehalogenases
dc.subject Dehalococcoides en_US
dc.title Genetic Identification of Reductive Dehalogenase Genes in Dehalococcoides en_US
dc.type Text
dc.type.genre Dissertation
dspace.entity.type Publication
local.contributor.corporatename School of Civil and Environmental Engineering
local.contributor.corporatename College of Engineering
relation.isOrgUnitOfPublication 88639fad-d3ae-4867-9e7a-7c9e6d2ecc7c
relation.isOrgUnitOfPublication 7c022d60-21d5-497c-b552-95e489a06569
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