Development and characterization of DehaloR^2, a novel anaerobic microbial consortium performing rapid dechlorination of TCE to ethene
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A novel anaerobic consortium, named DehaloR^2, that performs rapid and complete reductive dechlorination of trichloroethene (TCE) to ethene is described. DehaloR^2 was developed from estuarine sediment from the Back River of the Chesapeake Bay and has been stably maintained in the laboratory for over 2 years. Initial sediment microcosms showed incomplete reduction of TCE to DCE with a ratio of trans- to cis- isomers of 1.67. However, complete reduction to ethene was achieved within 10 days after transfer of the consortium to sediment-free media and was accompanied by a shift to cis-DCE as the prevailing intermediate metabolite. The microbial community shifted from dominance of the Proteobacterial phylum in the sediment to Firmicutes and Chloroflexi in DehaloR^2, containing the genera Acetobacterium, Clostridium, and the dechlorinators Dehalococcoides. Also present were Spirochaetes, possible acetogens, and Geobacter which encompass previously described dechlorinators. Rates of TCE to ethene reductive dechlorination reached 2.83 mM Cl− d−1 in batch bottles with a Dehalococcoides sp. density of 1.54E+11 gene copies per liter, comparing favorably to other enrichment cultures described in the literature and identifying DehaloR^2 as a promising consortium for use in bioremediation of chlorinated ethene-impacted environments.
KeywordsDehalococcoides Chlorinated ethenes Sediment microorganisms Reductive dechlorination
The authors thank Husen Zhang for guidance on the pyrosequencing and Prathap Parameswaran for guidance on the clone library construction. The project described was made possible in part by Award Number R01ES015445 from the National Institute of Environmental Health Sciences (NIEHS) and by start-up funds provided by the Arizona State University Fulton Schools of Engineering. The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIEHS or the National Institutes of Health.
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