title: The reductive dechlorination of 2,3,4,5-tetrachlorobiphenyl in three different sediment cultures: evidence for the involvement of phylogenetically similar Dehalococcoides-like bacterial populations.
abstract: Anaerobic cultures capable of reductively dechlorinating 2,3,4,5-tetrachlorobiphenyl (CB) were enriched from three different sediments, one estuarine, one marine and one riverine. Two different electron donors were used in enrichments with the estuarine sediment (elemental iron or a mixture of fatty acids). The removal of doubly flanked meta and para chlorines to form 2,3,5-CB and 2,4,5-CB was observed in all cultures. Bacterial community analysis of PCR-amplified 16S rRNA gene fragments revealed different communities in these cultures, with the exception of one common population that showed a high phylogentic relatedness to Dehalococcoides species. No Dehalococcoides-like populations were ever detected in control cultures to which no PCBs were added. In addition, the dynamics of this Dehalococcoides-like population were strongly correlated with dechlorination. Subcultures of the estuarine sediment culture demonstrated that the Dehalococcoides-like population disappeared when dechlorination was inhibited with 2-bromoethanesulfonate or when 2,3,4,5-CB had been consumed. These results provide evidence that Dehalococcoides-like populations were involved in the removal of doubly flanked chlorines from 2,3,4,5-CB. Furthermore, the successful enrichment of these populations from geographically distant and geochemically distinct environments indicates the widespread presence of these PCB-dechlorinating, Dehalococcoides-like organisms.
authors.affiliation: Department of Civil Engineering, University of Minnesota, Minneapolis, MN 55455-0116, USA.
authors.forename: Tao
authors.initials: T
authors.lastname: Yan
authors.forename: Timothy M
authors.initials: TM
authors.lastname: LaPara
authors.forename: Paige J
authors.initials: PJ
authors.lastname: Novak
mesh_terms: D017738:Alkanesulfonic Acids / Q000494:pharmacology; D015142:Baltimore; D044822:Biodiversity; D041862:Chloroflexi / Q000145:classification / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism*; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D004591:Electrophoresis, Polyacrylamide Gel; D005227:Fatty Acids / Q000378:metabolism; D019015:Geologic Sediments / Q000382:microbiology*; D007501:Iron / Q000378:metabolism; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D010802:Phylogeny; D011078:Polychlorinated Biphenyls / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012623:Seawater / Q000382:microbiology; D017422:Sequence Analysis, DNA; D014871:Water Microbiology
chemical_list: D017738:Alkanesulfonic Acids; D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D005227:Fatty Acids; D012336:RNA, Ribosomal, 16S; C018853:2-bromoethanesulfonic acid; C511766:2,3,4,5-tetrachlorobiphenyl; D011078:Polychlorinated Biphenyls; D007501:Iron