PCB reductive dechlorination in sediments of Venice lagoon: preliminary characterization of dechlorinating microflora

Reductive dechlorination processes towards weathered PCBs were recently detected and characterized in marine sediments of the Porto Marghera area of Venice lagoon and tentatively ascribed to sulfate-reducing spore-forming bacteria1,2,3. To gain deeper insights on native microflora, enrichments were performed in the presence of exogenous PCBs, electron donors and antibiotics. Increasing PCB-dechlorination and sulfate reduction rates, as well as progressive decrease of methanogenic activity were observed throughout subculturing. H2 and short chain organic acids did not affect the process. However, their addition together with vancomycin or ampicillin, resulted in higher dechlorination rates and extents. This suggests that Dehalococcoides-like bacteria are involved in PCB dechlorination, even though involvement of sulfate-reducing bacteria cannot be excluded. 1. Fava, F.; Gentilucci, S.; Zanaroli, G. Chemosphere 2003, 53, 101-109. 2. Fava, F; Zanaroli, G; Young, L.Y. FEMS Microbiol. Ecol. 2003, 44, 309-318. 3. Zanaroli, G.; Pérez-Jiménez, J.R.; Young, L.Y.; Fava, F. Biodegradation 2006, 17, 19-27.