title: Methanolinea mesophila sp. nov., a hydrogenotrophic methanogen isolated from rice field soil, and proposal of the archaeal family Methanoregulaceae fam. nov. within the order Methanomicrobiales.
abstract: A novel mesophilic, hydrogenotrophic methanogen, designated strain TNR(T), was isolated from an anaerobic, propionate-degradation enrichment culture that was originally established from a rice field soil sample from Taiwan. Cells were non-motile rods, 2.0-6.5 µm long by 0.3 µm wide. Filamentous (up to about 100 µm) and coccoid (about 1 µm in diameter) cells were also observed in cultures in the late exponential phase of growth. Strain TNR(T) grew at 20-40 °C (optimally at 37 °C), at pH 6.5-7.4 (optimally at pH 7.0) and in the presence of 0-25 g NaCl l(-1) (optimally at 0 g NaCl l(-1)). The strain utilized H(2)/CO(2) and formate for growth and produced methane. The G+C content of the genomic DNA was 56.4 mol%. Based on sequences of both the 16S rRNA gene and the methanogen-specific marker gene mcrA, strain TNR(T) was related most closely to Methanolinea tarda NOBI-1(T); levels of sequence similarities were 94.8 and 86.4 %, respectively. The 16S rRNA gene sequence similarity indicates that strain TNR(T) and M. tarda NOBI-1(T) represent different species within the same genus. This is supported by shared phenotypic properties, including substrate usage and cell morphology, and differences in growth temperature. Based on these genetic and phenotypic properties, strain TNR(T) is considered to represent a novel species of the genus Methanolinea, for which the name Methanolinea mesophila sp. nov. is proposed; the type strain is TNR(T) ( = NBRC 105659(T) = DSM 23604(T)). In addition, we also suggest family status for the E1/E2 group within the order Methanomicrobiales, for which the name Methanoregulaceae fam. nov. is proposed; the type genus of family is Methanoregula.
authors.affiliation: Subsurface Geobiology Advanced Research (SUGAR) Project, Extremobiosphere Research Program, Institute of Biogeosciences, 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 Environmental Systems Engineering, Nagaoka University of Technology, Nagaoka, Niigata 940-2188, Japan.|Subsurface Geobiology Advanced Research (SUGAR) Project, Extremobiosphere Research Program, Institute of Biogeosciences, Japan Agency for Marine-Earth Science & Technology (JAMSTEC), Yokosuka, Kanagawa 237-0061, Japan.
authors.forename: Masayuki
authors.initials: M
authors.lastname: Ehara
authors.affiliation: Department of Biology, National Cheng Kung University, Tainan 701, Taiwan, ROC.
authors.forename: I-Cheng
authors.initials: IC
authors.lastname: Tseng
authors.affiliation: Department of Environmental Systems Engineering, Nagaoka University of Technology, Nagaoka, Niigata 940-2188, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Yamaguchi
authors.affiliation: Department of Biology, Appalachian State University, Boone, NC 28608, USA.
authors.forename: Suzanna L
authors.initials: SL
authors.lastname: Bräuer
authors.affiliation: School of Life Sciences, Arizona State University, Tempe, AZ 85287, USA.
authors.forename: Hinsby
authors.initials: H
authors.lastname: Cadillo-Quiroz
authors.affiliation: Department of Microbiology, Cornell University, Ithaca, NY 14853, USA.
authors.forename: Stephen H
authors.initials: SH
authors.lastname: Zinder
authors.affiliation: Subsurface Geobiology Advanced Research (SUGAR) Project, Extremobiosphere Research Program, Institute of Biogeosciences, Japan Agency for Marine-Earth Science & Technology (JAMSTEC), Yokosuka, Kanagawa 237-0061, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Imachi
mesh_terms: D001482:Base Composition; D019641:DNA, Archaeal / Q000235:genetics; D004275:DNA, Ribosomal / Q000235:genetics; D006859:Hydrogen / Q000378:metabolism*; D008697:Methane / Q000378:metabolism*; D017018:Methanomicrobiales / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D008969:Molecular Sequence Data; D012275:Oryza / Q000254:growth & development; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012965:Sodium Chloride / Q000378:metabolism; D012988:Soil Microbiology; D013624:Taiwan
chemical_list: D019641:DNA, Archaeal; D004275:DNA, Ribosomal; D012336:RNA, Ribosomal, 16S; D012965:Sodium Chloride; D006859:Hydrogen; D008697:Methane