A Chloroflexi bacterium carrying a new reductive dehalogenase gene dechlorinates PCBs in marine sediments under in situ-like biogeochemical conditions

摘要

The reductive dechlorination of polychlorinated biphenyls (PCBs) has been documented in a number of laboratory slurry microcosms and in a few sediment-free cultures derived from contaminated rivers, lakes and estuaries, where a few Chloroflexi having low 16S rDNA sequence similarity with Dehalococcoides spp. have been shown to link their growth to PCB dehalorespiration (Wiegel and Wu, 2000; Bedard, 2008; Hiraishi, 2008). However, since PCB dechlorinating microorganisms have been so far studied in sediment slurries or sediment-free cultures established in defined culture media, their dechlorination activity under actual site biogeochemical conditions is unknown. In this work, we investigated the reductive dechlorination of Aroclor 1254 PCBs by the microbial community of a contaminated marine sediment of the Venice lagoon enriched in slurry microcosms of sterile sediment suspended in its sterile site water, i.e., under laboratory biogeochemical conditions that closely mime those occurring in situ.