| Abstract |
Two thermophilic, Gram-stain-positive, sporulating bacterial strains, which formed branched vegetative and aerial mycelia, were isolated from fallen leaves sampled from geothermal soils and designated ONI-1(T) and ONI-5(T). Strain ONI-1(T) grew at 50-74 °C, with optimum growth at 60-65 °C, and strain ONI-5(T) grew at 45-74 °C, with optimum growth at 60-65 °C. The pH range for growth of the strains was pH 4.6-8.0, with optimum growth at pH 7.0. The DNA G+C contents of strains ONI-1(T) and ONI-5(T) were 60.2 and 58.1 mol%, respectively. The major fatty acid was iso-C(17 : 0) and the major menaquinone was MK-9(H(2)). The cell walls of the strains contained glutamic acid, serine, glycine, histidine, alanine and ornithine. The polar lipids consisted of phosphatidylinositol, phosphatidylglycerol and a glycolipid. The cell-wall sugar was rhamnose. Detailed phylogenetic analysis based on 16S rRNA gene sequences indicated that the strains belong to the class Ktedonobacteria and that strains ONI-1(T) and ONI-5(T) are most closely related to Thermosporothrix hazakensis SK20-1(T) (85.3 and 84.5 % sequence similarity, respectively). 16S rRNA gene sequence similarity between the two strains was 96.6 %. Based on the phenotypic features and phylogenetic position, we propose that strains ONI-1(T) and ONI-5(T) constitute a novel genus containing two novel species, for which we propose the names Thermogemmatispora onikobensis gen. nov., sp. nov. (the type species; type strain ONI-1(T) = JCM 16817(T) = KCTC 19768(T)) and Thermogemmatispora foliorum sp. nov. (type strain ONI-5(T) = JCM 16818(T) = KCTC 19767(T)), within the new family Thermogemmatisporaceae fam. nov. and order Thermogemmatisporales ord. nov.
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