Enrichment of PCB dechlorinating bacteria from marine sediments of Venice lagoon under geochemical conditions that mime those occurring in situ.

Reductive dechlorination of PCBs has been reported in a number of slurry and sediment-free cultures from freshwater habitats established with defined mineral media, and was recently ascribed to bacteria of a dechlorinating clade within the phylum Chloroflexi. In this work, we enriched and characterized the PCB dechlorinating microbial population from a contaminated marine sediment suspended in its own site water. The enriched cultures were capable of rapidly and extensively dechlorinating the commercial mixture of PCBs Aroclor 1254 at the meta and para positions according to the dechlorination pattern H’. PCR-DGGE and quantitative PCR analyses on 16S rRNA genes revealed that a single Chloroflexi phylotype having 100% sequence identity with bacterium m-1 was enriched.