Dechlorination capabilities and diversity of reductive dehalogenases genes of a marine organohalide-respiring consortium

In this study, a PCB-dechlorinating consortium was sub-cultured in slurries of autoclave-sterilized sediment and filter-sterilized water of the Venice lagoon and shown to dechlorinate rapidly hexachlorobenzene (HCBe) and 1,2,3,5-tetrachlorobenzene (TeCBe) to 1,3,5-TCBe, which was then more slowly dehalogenated to 1,3-dichlorobenzene, 1-chlorobenzene and benzene. In addition, the consortium dechlorinated pentachlorophenol (PCP) to 2,4,6-trichloroplenol, 2,3,5-trichlorophenol (TCP) to 3,5-dichlorophenol, 1,2,3,4-tetrachloro-p-dioxin (TeCDD) to 1,2,4-TCDD and trichloroethene (TCE) to cis- and trans-DCE. The consortium sub-cultured on TCE in defined mineral medium was enriched in a Chloroflexi bacterium and was characterized by the presence of more than 70 reductive dehalogenase homologous genes, the majority of which were classified as novel rdhA homologs.