title: Methanoculleus horonobensis sp. nov., a methanogenic archaeon isolated from a deep diatomaceous shale formation.
abstract: A methanogenic organism from the domain Archaea, designated strain T10(T), was isolated from groundwater sampled from a deep diatomaceous shale formation located in Horonobe, Hokkaido, Japan. The strain utilized H2/CO2 and formate as substrates for methanogenesis. Cells were strictly anaerobic, Gram-negative-staining, flagellated, irregular coccoids, 0.7-1.6 µm in diameter, and occurred singly. The strain grew at 25-45 °C (optimum 37-42 °C), at pH 5.8-8.2 (optimum pH 6.7-6.8) and in the presence of 0-1.3 M NaCl (optimum 0.1-0.2 M NaCl). The G+C content of the genomic DNA was 62.9 mol%. 16S rRNA gene sequencing revealed that, although the strain is a member of the genus Methanoculleus, it clearly differed from all described species of this genus (95.5-98.3 % sequence similarity). Values for DNA-DNA hybridization with type strains of closely related Methanoculleus species were less than 50 %. Phenotypic and phylogenetic features of strain T10(T) clearly indicate that it represents a novel species of the genus Methanoculleus, for which the name Methanoculleus horonobensis sp. nov. is proposed. The type strain is T10(T) ( = DSM 21626(T) = JCM 15517(T)).
authors.affiliation: Horonobe Research Institute for the Subsurface Environment, Northern Advancement Center for Science and Technology, Horonobe-cho, Teshio-gun, Hokkaido 098-3221, Japan.
authors.forename: Satoru
authors.initials: S
authors.lastname: Shimizu
authors.affiliation: Horonobe Research Institute for the Subsurface Environment, Northern Advancement Center for Science and Technology, Horonobe-cho, Teshio-gun, Hokkaido 098-3221, Japan.
authors.forename: Akio
authors.initials: A
authors.lastname: Ueno
authors.affiliation: Horonobe Research Institute for the Subsurface Environment, Northern Advancement Center for Science and Technology, Horonobe-cho, Teshio-gun, Hokkaido 098-3221, Japan.
authors.forename: Shuji
authors.initials: S
authors.lastname: Tamamura
authors.affiliation: Graduate School of Biosphere Science, Hiroshima University, Higashi-Hiroshima 739-8528, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Naganuma
authors.affiliation: Horonobe Research Institute for the Subsurface Environment, Northern Advancement Center for Science and Technology, Horonobe-cho, Teshio-gun, Hokkaido 098-3221, Japan.
authors.forename: Katsuhiko
authors.initials: K
authors.lastname: Kaneko
mesh_terms: D001482:Base Composition; D019641:DNA, Archaeal / Q000235:genetics; D060587:Groundwater / Q000382:microbiology*; D007564:Japan; D019638:Methanomicrobiaceae / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification; D008969:Molecular Sequence Data; D009693:Nucleic Acid Hybridization; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA
chemical_list: D019641:DNA, Archaeal; D012336:RNA, Ribosomal, 16S