title: Spirochaeta psychrophila sp. nov., a psychrophilic spirochaete isolated from subseafloor sediment, and emended description of the genus Spirochaeta.
abstract: An obligately anaerobic, psychrophilic spirochaete, strain MO-SPC1(T), was isolated from a methanogenic microbial community grown in a continuous-flow bioreactor. Originally, this community was obtained from subseafloor sediments off the Shimokita Peninsula of Japan in the north-western Pacific Ocean. The cells were motile, Gram-stain-negative, helical, 0.25-0.55×3.6-15 µm, with a wavelength of approximately 0.5-0.6 µm. Strain MO-SPC1(T) grew at 0-18 °C (optimally at 15 °C), at pH 6.0-7.5 (optimally at pH 6.8-7.0) and in 20-70 g NaCl l(-1) (optimally at 30-40 NaCl l(-1)). The strain grew chemo-organotrophically with mono-, di- and polysaccharides. The major end products of glucose fermentation were acetate, ethanol, hydrogen and carbon dioxide. The abundant polar lipids of strain MO-SPC1(T) were diphosphatidylglycerol, phosphatidylglycerol, unknown phospholipids and an unknown lipid. The major cellular fatty acids (>5% of the total) were C(14 : 0), C(16 : 0), iso-C(13 : 0), iso-C(14 : 0), iso-C(15 : 0), anteiso-C(13 : 0) and anteiso-C(15 : 0). To the best of our knowledge, this is the first report of the fatty acids iso-C(13 : 0) and anteiso-C(13 : 0) from a species of the genus Spirochaeta. Isoprenoid quinones were not found. The G+C content of the genomic DNA was 39.8 mol%. 16S rRNA gene sequence-based phylogenetic analysis showed that strain MO-SPC1(T) was affiliated with the genus Spirochaeta, and its closest relatives were Spirochaeta isovalerica MA-2(T) (95.6% sequence identity) and Spirochaeta litoralis R1(T) (89.4%). Based on its phenotypic characteristics and phylogenetic traits, strain MO-SPC1(T) is placed in a separate taxon at the level of a novel species within the genus Spirochaeta, for which the name Spirochaeta psychrophila sp. nov. is proposed, reflecting its true psychrophilic physiology. The type strain is MO-SPC1(T) ( = JCM 17280(T) = DSM 23951(T)). To our knowledge, this is the first report of an isolate of the phylum Spirochaetes from a deep-sea sedimentary environment, and of an obligately psychrophilic nature.
authors.affiliation: Department of Subsurface Geobiology Analysis and Research (D-SUGAR), Japan Agency for Marine-Earth Science & Technology (JAMSTEC), Yokosuka, Kanagawa 237-0061, Japan.
authors.forename: Masayuki
authors.initials: M
authors.lastname: Miyazaki
authors.affiliation: Department of Subsurface Geobiology Analysis and Research (D-SUGAR), Japan Agency for Marine-Earth Science & Technology (JAMSTEC), Yokosuka, Kanagawa 237-0061, Japan.
authors.forename: Sanae
authors.initials: S
authors.lastname: Sakai
authors.affiliation: Department of Subsurface Geobiology Analysis and Research (D-SUGAR), Japan Agency for Marine-Earth Science & Technology (JAMSTEC), Yokosuka, Kanagawa 237-0061, Japan.
authors.forename: Yuko
authors.initials: Y
authors.lastname: Yamanaka
authors.affiliation: Department of Subsurface Geobiology Analysis and Research (D-SUGAR), Japan Agency for Marine-Earth Science & Technology (JAMSTEC), Yokosuka, Kanagawa 237-0061, Japan.
authors.forename: Yumi
authors.initials: Y
authors.lastname: Saito
authors.affiliation: Department of Subsurface Geobiology Analysis and Research (D-SUGAR), Japan Agency for Marine-Earth Science & Technology (JAMSTEC), Yokosuka, Kanagawa 237-0061, Japan.
authors.forename: Ken
authors.initials: K
authors.lastname: Takai
authors.affiliation: Department of Subsurface Geobiology Analysis and Research (D-SUGAR), Japan Agency for Marine-Earth Science & Technology (JAMSTEC), Yokosuka, Kanagawa 237-0061, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Imachi
mesh_terms: D015373:Bacterial Typing Techniques; D001482:Base Composition; D019149:Bioreactors / Q000382:microbiology*; D004269:DNA, Bacterial / Q000235:genetics; D005227:Fatty Acids / Q000737:chemistry; D019015:Geologic Sediments / Q000382:microbiology*; D007564:Japan; D008969:Molecular Sequence Data; D010743:Phospholipids / Q000737:chemistry; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012623:Seawater / Q000382:microbiology; D017422:Sequence Analysis, DNA; D013142:Spirochaeta / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification
chemical_list: D004269:DNA, Bacterial; D005227:Fatty Acids; D010743:Phospholipids; D012336:RNA, Ribosomal, 16S