title: Dehalococcoides mccartyi gen. nov., sp. nov., obligately organohalide-respiring anaerobic bacteria relevant to halogen cycling and bioremediation, belong to a novel bacterial class, Dehalococcoidia classis nov., order Dehalococcoidales ord. nov. and family Dehalococcoidaceae fam. nov., within the phylum Chloroflexi.
abstract: Six obligately anaerobic bacterial isolates (195(T), CBDB1, BAV1, VS, FL2 and GT) with strictly organohalide-respiring metabolisms were obtained from chlorinated solvent-contaminated aquifers, contaminated and uncontaminated river sediments or anoxic digester sludge. Cells were non-motile with a disc-shaped morphology, 0.3-1 µm in diameter and 0.1-0.2 µm thick, and characteristic indentations on opposite flat sides of the cell. Growth occurred in completely synthetic, reduced medium amended with a haloorganic electron acceptor (mostly chlorinated but also some brominated compounds), hydrogen as electron donor, acetate as carbon source, and vitamins. No other growth-supporting redox couples were identified. Aqueous hydrogen consumption threshold concentrations were <1 nM. Growth ceased when vitamin B(12) was omitted from the medium. Addition of sterile cell-free supernatant of Dehalococcoides-containing enrichment cultures enhanced dechlorination and growth of strains 195 and FL2, suggesting the existence of so-far unidentified stimulants. Dechlorination occurred between pH 6.5 and 8.0 and over a temperature range of 15-35 °C, with an optimum growth temperature between 25 and 30 °C. The major phospholipid fatty acids were 14 : 0 (15.7 mol%), br15 : 0 (6.2 mol%), 16 : 0 (22.7 mol%), 10-methyl 16 : 0 (25.8 mol%) and 18 : 0 (16.6 mol%). Unusual furan fatty acids including 9-(5-pentyl-2-furyl)-nonanoate and 8-(5-hexyl-2-furyl)-octanoate were detected in strains FL2, BAV1 and GT, but not in strains 195(T) and CBDB1. The 16S rRNA gene sequences of the six isolates shared more than 98 % identity, and phylogenetic analysis revealed an affiliation with the phylum Chloroflexi and more than 10 % sequence divergence from other described isolates. The genome sizes and G+C contents ranged from 1.34 to 1.47 Mbp and 47 to 48.9 mol% G+C, respectively. Based on 16S rRNA gene sequence comparisons, genome-wide average nucleotide identity and phenotypic characteristics, the organohalide-respiring isolates represent a new genus and species, for which the name Dehalococcoides mccartyi gen. nov., sp. nov. is proposed. Isolates BAV1 ( = ATCC BAA-2100  = JCM 16839  = KCTC 5957), FL2 ( = ATCC BAA-2098  = DSM 23585  = JCM 16840  = KCTC 5959), GT ( = ATCC BAA-2099  = JCM 16841  = KCTC 5958), CBDB1, 195(T) ( = ATCC BAA-2266(T)  = KCTC 15142(T)) and VS are considered strains of Dehalococcoides mccartyi, with strain 195(T) as the type strain. The new class Dehalococcoidia classis nov., order Dehalococcoidales ord. nov. and family Dehalococcoidaceae fam. nov. are described to accommodate the new taxon.
authors.affiliation: Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA.|Department of Civil and Environmental Engineering, University of Tennessee, Knoxville, TN 37996, USA.|Department of Microbiology, University of Tennessee, Knoxville, TN 37996, USA.
authors.forename: Frank E
authors.initials: FE
authors.lastname: Löffler
authors.affiliation: Department of Civil and Environmental Engineering, University of Tennessee, Knoxville, TN 37996, USA.|Department of Microbiology, University of Tennessee, Knoxville, TN 37996, USA.
authors.forename: Jun
authors.initials: J
authors.lastname: Yan
authors.affiliation: Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA.|Department of Microbiology, University of Tennessee, Knoxville, TN 37996, USA.
authors.forename: Kirsti M
authors.initials: KM
authors.lastname: Ritalahti
authors.affiliation: Helmholtz Centre for Environmental Research - UFZ, Permoserstr. 15, D-04318 Leipzig, Germany.
authors.forename: Lorenz
authors.initials: L
authors.lastname: Adrian
authors.affiliation: Department of Chemical Engineering, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Edwards
authors.affiliation: School of Civil and Environmental Engineering and School of Biology, Georgia Institute of Technology, Atlanta, GA 30332, USA.
authors.forename: Konstantinos T
authors.initials: KT
authors.lastname: Konstantinidis
authors.affiliation: Helmholtz Centre for Environmental Research - UFZ, Permoserstr. 15, D-04318 Leipzig, Germany.
authors.forename: Jochen A
authors.initials: JA
authors.lastname: Müller
authors.affiliation: Department of Microbiology, Cornell University, Ithaca, NY 14853, USA.
authors.forename: Heather
authors.initials: H
authors.lastname: Fullerton
authors.affiliation: Department of Microbiology, Cornell University, Ithaca, NY 14853, USA.
authors.forename: Stephen H
authors.initials: SH
authors.lastname: Zinder
authors.affiliation: Departments of Civil and Environmental Engineering and of Chemical Engineering, Stanford University, Stanford, CA 94305, USA.
authors.forename: Alfred M
authors.initials: AM
authors.lastname: Spormann
mesh_terms: D015373:Bacterial Typing Techniques; D001482:Base Composition; D001673:Biodegradation, Environmental; D041862:Chloroflexi / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification; D004269:DNA, Bacterial / Q000235:genetics; D005227:Fatty Acids / Q000032:analysis; D006219:Halogens / Q000378:metabolism*; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D012722:Sewage / Q000382:microbiology*
chemical_list: D004269:DNA, Bacterial; D005227:Fatty Acids; D006219:Halogens; D012336:RNA, Ribosomal, 16S; D012722:Sewage