Methanospirillum lacunae sp. nov., a methane-producing archaeon isolated from a puddly soil, and emended descriptions of the genus Methanospirillum and Methanospirillum hungatei

Abstract

A mesophilic, hydrogenotrophic methanogen, designated strain Ki8-1T, was isolated from soil. Cells were strictly anaerobic, Gram-stain-negative, non-sporulating, motile by means of a single flagellum or tufted flagella, and curved or wavy rod-shaped (11–25 μm long). The temperature and pH for optimum growth were 30 °C and 7.5. The strain grew best in basal medium without the addition of NaCl. Methane was produced from H2and formate. Acetate or yeast extract was required for growth. The G+C content of the genomic DNA of strain Ki8-1Twas 45.3 mol%. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain Ki8-1Twas a member of the genusMethanospirillumand showed 95.1 % sequence similarity toMethanospirillum hungateiNBRC 100397T. On the basis of its phenotypic characteristics and phylogenetic position, strain Ki8-1Tis considered to represent a novel species of the genusMethanospirillum, for which the nameMethanospirillum lacunaesp. nov. is proposed. The type strain is Ki8-1T(NBRC 104920T=JCM 16384T=DSM 22751T). Emended descriptions of the genusMethanospirillumand ofMethanospirillum hungateiare also provided.