title: Identification of a microorganism that links its growth to the reductive dechlorination of 2,3,5,6-chlorobiphenyl.
abstract: Anaerobic bacteria reductively dechlorinate polychlorinated biphenyls (PCBs) in aquatic sediments, but these microorganisms remain uncultured and, until now, unidentified. Through denaturing gradient gel electrophoresis (DGGE) of 16S rDNA from a highly enriched ortho-PCB dechlorinating culture, the growth of a single microorganism was shown to be dependent upon the presence and dechlorination of 2,3,5,6-tetrachlorobiphenyl. This is the first identification of a microorganism that catalyses the reductive dechlorination of a PCB. The organism, bacterium o-17, has high sequence similarity with the green non-sulphur bacteria and with a group that includes Dehalococcoides ethenogenes. Bacterium o-17 required acetate for dechlorination and growth. H2:CO2 (80:20 at 101 kPa) did not support dechlorination or growth of the dechlorinator. Archaeal 16S rDNA was not detected in actively dechlorinating bromoethanesulphonate-treated non-methanogenic cultures, which indicated that methanogenic Archaea were not required for dechlorination. The consistent association with dechlorinating activity combined with high similarity to other known dechlorinating microorganisms indicates that bacterium o-17 catalyses the reductive ortho-dechlorination of 2,3,5,6-tetrachlorobiphenyl.
authors.affiliation: Department of Microbiology and Immunology, Marine Biomedicine and Envionmental Sciences Program, Medical University of South Carolina, Charleston, SC, USA.
authors.forename: L A
authors.initials: LA
authors.lastname: Cutter
authors.forename: J E
authors.initials: JE
authors.lastname: Watts
authors.forename: K R
authors.initials: KR
authors.lastname: Sowers
authors.forename: H D
authors.initials: HD
authors.lastname: May
mesh_terms: D000085:Acetates / Q000378:metabolism; D001421:Bacteria, Anaerobic / Q000145:classification / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D001673:Biodegradation, Environmental; D002713:Chlorine / Q000378:metabolism*; D004586:Electrophoresis / Q000379:methods; D006859:Hydrogen / Q000378:metabolism; D008697:Methane / Q000378:metabolism; D008969:Molecular Sequence Data; D011078:Polychlorinated Biphenyls / Q000378:metabolism*; D012336:RNA, Ribosomal, 16S / Q000737:chemistry / Q000378:metabolism
chemical_list: D000085:Acetates; D012336:RNA, Ribosomal, 16S; D002713:Chlorine; D006859:Hydrogen; D011078:Polychlorinated Biphenyls; C078132:2,3,5,6-tetrachlorobiphenyl; D008697:Methane