Sulfurihydrogenibium yellowstonense sp. nov., an extremely thermophilic, facultatively heterotrophic, sulfur-oxidizing bacterium from Yellowstone National Park, and emended descriptions of the genus Sulfurihydrogenibium, S. subterraneum and S. azorense

A novel thermophilic, sulfur-oxidizing Gram-negative bacterium, designated strain SS-5, was isolated from the Calcite Hot Springs in Yellowstone National Park, USA. The cells were motile rods (1?2–2?8 mm long and 0?6–0?8 mm wide). The new isolate was a facultative heterotroph capable of using elemental sulfur or thiosulfate as an electron donor and O2 (1–18 %; optimum 6 %, v/v) as an electron acceptor. Hydrogen did not support growth. The isolate grew autotrophically with CO2. In addition, strain SS-5 T utilized various organic carbon sources such as yeast extract, tryptone, sugars, amino acids and organic acids. Growth was observed between 55 and 78 6C (optimum 70 6C; 3?5 h doubling time), pH 6?0 and 8?0 (optimum pH 7?5), and 0 and 0?6 % (w/v) NaCl (optimum 0 %). The G+C content of the genomic DNA was 32 mol%. Phylogenetic analysis based on the 16S rRNA gene sequence indicated that the isolate was a member of the genus Sulfurihydrogenibium. On the basis of the physiological and molecular characteristics of the new isolate, we propose the name Sulfurihydrogenibium yellowstonense sp. nov. with SS-5 (=JCM 12773=OCM 840) as the type strain. In addition, emended descriptions of the genus Sulfurihydrogenibium, Sulfurihydrogenibium subterraneum and Sulfurihydrogenibium azorense are proposed.