Involvement of Dehalobacter strains in the anaerobic dechlorination of 2,4,6-trichlorophenol.

A culture reductively dechlorinating 2,4,6-trichlorophenol (TCP) was enriched from a sediment contaminated with chlorinated aliphatic hydrocarbons. The culture dechlorinated 100 μM of 2,4,6-TCP to 4-chlorophenol within 15 days utilizing H2 and a yeast extract as an electron donor and carbon source, respectively. Besides 2,4,6-TCP, the culture could also dehalogenate chlorophenols at ortho position and 2,4,6-tribromophenol at ortho and para positions, as well as chlorinated ethenes and ethanes. A 16S rRNA gene clone library analysis showed that the bacterial community was composed of members of the classes Clostridia, Bacteroidia, Spirochetes, and Epsilonproteobacteria. The phylogenetic and physiological characterization of the culture confirmed two novel Dehalobacter strains, TCP-5 and TCP-6, that were involved in the reductive dehalogenation of 2,4,6-TCP and other halogenated compounds. The study was significant as the first report to demonstrate the involvement of Dehalobacter in the reductive dehalogenation of both halogenated aromatic and aliphatic compounds.