title: Methanomicrobium antiquum sp. nov., a hydrogenotrophic methanogen isolated from deep sedimentary aquifers in a natural gas field.
abstract: A mesophilic, hydrogenotrophic methanogen, designated strain MobHT, was isolated from sediments derived from deep sedimentary, natural-gas-bearing aquifers in Japan. Strain MobHT utilized H2/CO2 or formate, but not ethanol, 1-propanol, 2-propanol, 2-butanol or cyclopentanol, for growth and methane production. In addition, acetate and tungsten were required for growth. Yeast extract stimulated the growth, but was not required. The cells were weakly motile with multiple flagella, presented as a curved-rod-shaped (0.8×2.0 µm) and occurred singly or in pairs. Strain MobHT grew at 15-40 °C (optimum 35 °C) and at pH 5.9-7.9 (optimum pH 7.0-7.5). The sodium chloride range for growth was 0-5.8 % (optimum 2 %). The G+C content of the genomic DNA was 37.6 mol%. In the phylogenetic tree based on the 16S rRNA gene sequences, strain MobHT clustered together with Methanomicrobium mobile (95.4 % in sequence similarity), and formed a distinct clade from Methanolacinia petrolearia SEBR 4847T (95.6 %) and Methanolacinia paynteri G-2000T (95.4 %). The two species of the genus Methanolacinia utilized 2-propanol, whereas strain MobHT and Methanomicrobium mobile, the sole species of the genus Methanomicrobium, do not. Based on phenotypic and phylogenetic features, we propose a novel species for the isolate with the name, Methanomicrobiumantiquum sp. nov. The type strain is MobHT (=DSM 21220T=NBRC 104160T).
authors.affiliation: Institute for Geo-Resources and Environment, Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8567, Japan.
authors.forename: Hanako
authors.initials: H
authors.lastname: Mochimaru
authors.affiliation: Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8566, Japan.
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Tamaki
authors.affiliation: Institute for Geo-Resources and Environment, Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8567, Japan.
authors.forename: Taiki
authors.initials: T
authors.lastname: Katayama
authors.affiliation: Department of Subsurface Geobiological Analysis and Research, Japan Agency for Marine-Earth Science & Technology (JAMSTEC), Yokosuka, Kanagawa 237-0061, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Imachi
authors.affiliation: Institute for Geo-Resources and Environment, Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8567, Japan.
authors.forename: Susumu
authors.initials: S
authors.lastname: Sakata
authors.affiliation: Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8566, Japan.
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Kamagata
mesh_terms: D001482:Base Composition; D019641:DNA, Archaeal / Q000235:genetics; D060587:Groundwater / Q000382:microbiology*; D007564:Japan; D008697:Methane; D019638:Methanomicrobiaceae / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification; D059206:Natural Gas; D061329:Oil and Gas Fields / Q000382:microbiology*; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA
chemical_list: D019641:DNA, Archaeal; D059206:Natural Gas; D012336:RNA, Ribosomal, 16S; D008697:Methane