Sulfurihydrogenibium rodmanii sp nov., a sulfur-oxidizing chemolithoautotroph from the Uzon Caldera, Kamchatka Peninsula, Russia, and emended description of the genus Sulfurihydrogenibium

Four thermophilic, sulfur-oxidizing, chemolithoautotrophic strains with >99% 16S rRNA gene sequence similarity were isolated from terrestrial hot springs in the Geyser Valley and the Uzon Caldera, Kamchatka, Russia. One strain, designated UZ3-5(T), was characterized fully. Cells of UZ3-5(T) were Gram-negative, motile, slightly oval rods (about 0.7 mu m wide and 1.0 mu m long) with multiple polar flagella. All four strains were obligately microaerophilic chemolithoautotrophs and could use elemental sulfur or thiosulfate as electron donors and oxygen (1-14%, v/v) as the electron acceptor. Strain UZ3-5(T) grew at temperatures between 55 and 80 degrees C (optimally at 75 degrees C; 1.1 h doubling time), at pH 5.0-7.2 (optimally at pH 6.0-6.3) and at 0-0.9% NaCl (optimally in the absence of NaCl). The G + C content of the genomic DNA of strain UZ3-5(T) was 35 mol%. Phylogenetic analysis revealed that strain UZ3-5(T) was a member of the genus Sulfurihydrogenibium, its closest relative in culture being Sulfurihydrogenibium azorense Az-Fu1(T) (98.3% 16S rRNA gene sequence similarity). On the basis of its physiological and molecular characteristics, strain UZ3-5(T) represents a novel species of the genus Sulfurihydrogenibium, for which the name Sulfurihydrogenibium rodmanii sp. nov. is proposed. The type strain is UZ3-5(T) (= OCM 900(T) = ATCC BAA-1536(T) = DSM 19533(T)).