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

1 Department of Molecular and Cellular Biology, Portland State University, PO Box 751, Portland, OR 97207-0751, USA 2 Department of Microbiology, College of Biological Science, University of Guelph, Guelph, Ontario N1G 2W1, Canada Correspondence Anna-Louise Reysenbach reysenbacha{at}pdx.edu 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 µm wide and 1.0 µm 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 °C (optimally at 75 °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 ). Present address: John Wilson and Partners, 100 Wickham Street, Fortitude Valley, Queensland 4006, Australia. The GenBank/EMBL/DDBJ accession numbers for the partial 16S rRNA gene sequences of strain UZ3-5 T , GV2-1C1, UZ1-1C1 and UZ1-1C2 are AM259502 , AM259494 , AM259495 and AM259496 , respectively. Graphs showing the effects of temperature and pH on the growth of strain UZ3-5 T are available as supplementary figures with the online version of this paper.