Growth of Dehalobacter and Dehalococcoides spp. during Degradation of Chlorinated Ethanes

Abstract

Mixed anaerobic microbial subcultures enriched from a multilayered aquifer at a former chlorinated solvent disposal facility in West Louisiana were examined to determine the organism(s) involved in the dechlorination of the toxic compounds 1,2-dichloroethane (1,2-DCA) and 1,1,2-trichloroethane (1,1,2-TCA) to ethene. Sequences phylogenetically related to Dehalobacter and Dehalococcoides, two genera of anaerobic bacteria that are known to respire with chlorinated ethenes, were detected through cloning of bacterial 16S rRNA genes. Denaturing gradient gel electrophoresis analysis of 16S rRNA gene fragments after starvation and subsequent reamendment of culture with 1,2-DCA showed that the Dehalobacter sp. grew during the dichloroelimination of 1,2-DCA to ethene, implicating this organism in degradation of 1,2-DCA in these cultures. Species-specific real-time quantitative PCR was further used to monitor proliferation of Dehalobacter and Dehalococcoides during the degradation of chlorinated ethanes and showed that in fact both microorganisms grew simultaneously during the degradation of 1,2-DCA. Conversely, Dehalobacter grew during the dichloroelimination of 1,1,2-TCA to vinyl chloride (VC) but not during the subsequent reductive dechlorination of VC to ethene, whereas Dehalococcoides grew only during the reductive dechlorination of VC but not during the dichloroelimination of 1,1,2-TCA. This demonstrated that in mixed cultures containing multiple dechlorinating microorganisms, these organisms can have either competitive or complementary dechlorination activities, depending on the chloro-organic substrate.

Dechlorination and organohalide-respiring bacteria dynamics in sediment samples of the Yangtze Three Gorges Reservoir

“…and Dehalococcoides spp. (Smits et al 2004;Grostern and Edwards 2006) or Dehalococcoides bacteria (Schmidt et al 2006;Aktaş et al 2012). It has been shown recently that in the field, often several dechlorinating bacteria are present simultaneously (Rouzeau-Szynalski et al 2011).…”

A 1,1,1-Trichloroethane-Degrading Anaerobic Mixed Microbial Culture Enhances Biotransformation of Mixtures of Chlorinated Ethenes and Ethanes

“…To identify the bacterial populations present, bacterial 16S rRNA genes were cloned from MS following extraction of total genomic DNA, as previously described (25). Thirty-seven 16S rRNA gene clones were sequenced by the University Health Network Research DNA Sequencing Facility (Toronto, ON, Canada) with the primer 8f (38), and the closest sequence match was identified with a BLASTN search of GenBank (www.ncbi.nlm.nih.gov/blast).…”

Overview of organohalide-respiring bacteria and a proposal for a classification system for reductive dehalogenases

“…Dehalococcoides mccartyi strain MB [60,61]). rdhA genes from consortia (KB-1, ACT-3 and WL) were included in cases where metagenome sequences or quantitative PCR studies allow connection of rdhA sequences with specific OHRB genera [24,[84][85][86]. Additionally, the rdhA genes were required to be full-length or close to full-length (greater than 300 amino acids), which excluded many partial rdhA genes in the database.…”