Identification of Key Microbial Players Carrying Out Reductive Dechlorination of PCBs in Freshwater Sediments

Rensselaer Polytechnic Institute, Troy NY

Investigators

Abstract

Polychlorinated biphenyls (PCBs) are widespread contaminants of aquatic sediments. Anaerobic microorganisms in many of these contaminated sediments have the capacity to remove chlorine from the PCBs. Dechlorination reduces the persistence and potential toxicity of PCBs. To date, none of the dechlorinating microorganisms have been identified and thus nothing is known about their ecology or about the evolution of PCB-dechlorinating enzymes/pathways. Previous studies have shown that PCB-dechlorinating microorganisms are present in the Housatonic River (Lenox, MA) and that they exhibit three distinct PCB-dechlorinating activities. Each of these activities has distinct substrates, targeted chlorine positions, and pH and temperature optima. This research project will use molecular techniques to identify the key changes in microbial community structure that occur when these different activities are stimulated and enriched and will use 16S rRNA-based phylogenetic analysis to identify the key microbial players carrying out reductive dechlorination of PCBs. Long-term goals include isolation of PCB-dechlorinating bacteria and isolation and characterization of their PCB-dechlorinating enzymes. This research will expand our understanding of an important environmental process and of anaerobic sediment communities.