Characteriaztion of microbial consortia from marine sediments of the venice lagoon capable of pcb dechlorination

In this study we present the characterization of microbial communities supporting PCBs dechlorination, after enrichment from Venice lagoon’s (VL) sediments. The sediment with the native microbiota were sub-cultured in seven successive passages in slurry microcosms spiked with coplanar PCBs or Aroclor 1254, different electron donors and antibiotics. Increasing PCBs-dechlorination rates along with increases in sulfate-reduction and decline in methanogenic activities occurred throughout subculturing. Quantitative real-time PCR and denaturing gradient gel electrophoresis over the 16S rRNA gene of Dehalococcoides-like bacteria, indicated that one bacterial taxon (SF1/M1), strictly related to the genus Dehaloccoides, proliferated in all the microcosms actively dechlorinating PCBs but not in those without the chlorinated compounds. SF1/M1 has been previously reported to actively dechlorinate 3,5-dichlorobiphenyl. A novel reductive dehalogenase gene sequence has been detected only in microcosms enriched with SF1/M1 supporting a dehalorespiring activity by these bacteria.