Sphaerochaeta multiformis sp nov.; an Anaerobic, Psychrophilic Bacterium Isolated from Subseafloor sediment, and Emended Description of the Genus Sphaerochaeta


Masayuki Miyazaki, Sanat Sakai, Kirsti M. Ritalahti, Yayoi Saito, Yuko Yamanaka, Yumi Saito, Akihiko Tame, Katsuyuki Uematsu, Frank E. Löffler, Ken Sakai, Hiroyuki Imachi


An anaerobic, psychrophilic bacterium, strain MO-SPC2(T), was isolated from a methanogenic microbial community in a continuous-flow bioreactor that was established from subseafloor sediments collected from off the Shimokita Peninsula of Japan in the north-western Pacific Ocean. Cells were pleomorphic: spherical, annular, curved rod, helical and coccoid cell morphologies were observed. Motility only occurred in helical cells. Strain MO-SPC2(T) grew at 0-17 °C (optimally at 9 °C), at pH 6.0-8.0 (optimally at pH 6.8-7.2) and in 20-40 g NaCl l(-1) (optimally at 20-30 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-SPC2(T) were phosphatidylglycolipids, phospholipids and glycolipids. The major cellular fatty acids were C14 : 0, C16 : 0 and C16 : 1ω9. Isoprenoid quinones were not detected. The G+C content of the DNA was 32.3 mol%. 16S rRNA gene-based phylogenetic analysis showed that strain MO-SPC2(T) was affiliated with the genus Sphaerochaeta within the phylum Spirochaetes, and its closest relatives were Sphaerochaeta pleomorpha Grapes(T) (88.4 % sequence identity), Sphaerochaeta globosa Buddy(T) (86.7 %) and Sphaerochaeta coccoides SPN1(T) (85.4 %). Based on phenotypic characteristics and phylogenetic traits, strain MO-SPC2(T) is considered to represent a novel species of the genus Sphaerochaeta, for which the name Sphaerochaeta multiformis sp. nov. is proposed. The type strain is MO-SPC2(T) ( = JCM 17281(T) = DSM 23952(T)). An emended description of the genus Sphaerochaeta is also proposed.

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Miyazaki M, Sakai S, Ritalahti KM, Saito Y, Yamanaka Y, Saito Y, Tame A, Uematsu K, Loeffler FE, Takai K, Imachi H.2014. Sphaerochaeta multiformis sp nov.; an anaerobic, psychrophilic bacterium isolated from subseafloor sediment, and emended description of the genus Sphaerochaeta. International Journal of Systematic and Evolutionary Microbiology 64:4147-4154.