Respiratory Vinyl Chloride Reductive Dechlorination to Ethene in TceA-Expressing Dehalococcoides mccartyi

Jun Yan, Jingjing Wang, Manuel I. Villalobos Solis, Huijuan Jin, Karuna Chourey, Xiuying Li, Yi Yang, Yongchao Yin, Robert L. Hettich, Frank E. Löffler

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47 Scopus citations

Abstract

Bioremediation of chlorinated ethenes in anoxic aquifers hinges on organohalide-respiring Dehalococcoidia expressing vinyl chloride (VC) reductive dehalogenase (RDase). The tceA gene encoding the trichloroethene-dechlorinating RDase TceA is frequently detected in contaminated groundwater but not recognized as a biomarker for VC detoxification. We demonstrate that tceA-carrying Dehalococcoides mccartyi (Dhc) strains FL2 and 195 grow with VC as an electron acceptor when sufficient vitamin B12 (B12) is provided. Strain FL2 cultures that received 50 μg L-1 B12 completely dechlorinated VC to ethene at rates of 14.80 ± 1.30 μM day-1 and attained 1.64 ± 0.11 × 108 cells per μmol of VC consumed. Strain 195 attained similar growth yields of 1.80 ± 1.00 × 108 cells per μmol of VC consumed, and both strains could be consecutively transferred with VC as the electron acceptor. Proteomic analysis demonstrated TceA expression in VC-grown strain FL2 cultures. Resequencing of the strain FL2 and strain 195 tceA genes identified non-synonymous substitutions, although their consequences for TceA function are currently unknown. The finding that Dhc strains expressing TceA respire VC can explain ethene formation at chlorinated solvent sites, where quantitative polymerase chain reaction analysis indicates that tceA dominates the RDase gene pool.

Original languageEnglish
Pages (from-to)4831-4841
Number of pages11
JournalEnvironmental Science and Technology
Volume55
Issue number8
DOIs
StatePublished - Apr 20 2021

Funding

This work was supported by the Strategic Environmental Research and Development Program (SERDP project ER-2312), with additional support provided by the National Institute of Environmental Health Sciences (award R01ES024294), and by the National Natural Science Foundation of China (grant numbers 41673126, 41977295, and 41907287).

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