title: Chloroflexus islandicus sp. nov., a thermophilic filamentous anoxygenic phototrophic bacterium from a geyser.
abstract: A novel, thermophilic filamentous anoxygenic phototrophic bacterium, strain isl-2T, was isolated from the Strokkur Geyser, Iceland. Strain isl-2T formed unbranched multicellular filaments with gliding motility. The cells formed no spores and stained Gram-negative. The existence of pili was described in a species of the genus Chloroflexus for the first time, to our knowledge. Optimal growth occurred at a pH range of 7.5-7.7 and at a temperature of 55 °C. Strain isl-2T grew photoheterotrophically under anaerobic conditions in the light and chemoheterotrophically under aerobic conditions in the dark. The major cellular fatty acids were C18 : 1ω9, C16 : 0, C18 : 0 and C18 : 0-OH. The major quinone was menaquinone-10. The photosynthetic pigments were bacteriochlorophylls c and a as well as β- and γ-carotenes. The results of phylogenetic analysis of the 16S rRNA gene sequences placed strain isl-2T into the genus Chloroflexus of the phylum Chloroflexi with Chloroflexus aggregans DSM 9485T as the closest relative (97.0 % identity). The whole-genome sequence of isl-2T was determined. Average nucleotide identity values obtained for isl-2T in comparison to available genomic sequences of other strains of members of the genus Chloroflexus were 81.4 % or less and digital DNA-DNA hybridisation values 22.8 % or less. The results of additional phylogenetic analysis of the PufLM and BchG amino acid sequences supported the separate position of the isl-2T phylotype from the phylotypes of other members of the genus Chloroflexus. On the basis of physiological and phylogenetic data as well as genomic data, it was suggested that isl-2T represents a novel species within the genus Chloroflexus, with the proposed name Chloroflexus islandicus sp. nov. The type strain of the species is isl-2T (=VKM B-2978T,=DSM 29225T,=JCM 30533T).
authors.affiliation: Research Center of Biotechnology of the Russian Academy of Sciences, 33, bld. 2. Leninsky Ave., Moscow 119071, Russian Federation.
authors.forename: Vasil A
authors.initials: VA
authors.lastname: Gaisin
authors.affiliation: Research Center of Biotechnology of the Russian Academy of Sciences, 33, bld. 2. Leninsky Ave., Moscow 119071, Russian Federation.
authors.forename: Alexander M
authors.initials: AM
authors.lastname: Kalashnikov
authors.affiliation: Research Center of Biotechnology of the Russian Academy of Sciences, 33, bld. 2. Leninsky Ave., Moscow 119071, Russian Federation.
authors.forename: Denis S
authors.initials: DS
authors.lastname: Grouzdev
authors.affiliation: Research Center of Biotechnology of the Russian Academy of Sciences, 33, bld. 2. Leninsky Ave., Moscow 119071, Russian Federation.
authors.forename: Marina V
authors.initials: MV
authors.lastname: Sukhacheva
authors.affiliation: Research Center of Biotechnology of the Russian Academy of Sciences, 33, bld. 2. Leninsky Ave., Moscow 119071, Russian Federation.
authors.forename: Boris B
authors.initials: BB
authors.lastname: Kuznetsov
authors.affiliation: Research Center of Biotechnology of the Russian Academy of Sciences, 33, bld. 2. Leninsky Ave., Moscow 119071, Russian Federation.
authors.forename: Vladimir M
authors.initials: VM
authors.lastname: Gorlenko
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry; D015373:Bacterial Typing Techniques; D001429:Bacteriochlorophylls / Q000737:chemistry; D001482:Base Composition; D002338:Carotenoids / Q000737:chemistry; D041861:Chloroflexus / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification; D004269:DNA, Bacterial / Q000235:genetics; D005227:Fatty Acids / Q000737:chemistry; D007055:Iceland; D009693:Nucleic Acid Hybridization; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D014871:Water Microbiology
chemical_list: D001426:Bacterial Proteins; D001429:Bacteriochlorophylls; D004269:DNA, Bacterial; D005227:Fatty Acids; D012336:RNA, Ribosomal, 16S; D002338:Carotenoids; C002084:bacteriochlorophyll c