Tepidicella xavieri gen. nov., sp. nov., a betaproteobacterium isolated from a hot spring runoff.

Strains TU-16T and TU-18, two non-pigmented bacterial isolates with an optimum growth temperature of about 45 degrees C and an optimum pH of about 8.5-9.0, were recovered from the Furnas geothermal area on the Island of São Miguel in the Azores. Phylogenetic analysis of the 16S rRNA gene sequence of these strains indicated that they represent a novel species in a new genus of the phylum Betaproteobacteria. The major fatty acids of strains TU-16T and TU-18 were 16 : 0 and 18 : 1omega7c. Ubiquinone 8 was the major respiratory quinone and the major polar lipids were phosphatidylethanolamine and phosphatidylglycerol. The novel isolates were aerobic; thiosulfate was oxidized to sulfate in the presence of a metabolizable carbon source. The organism assimilated organic acids and amino acids, but did not assimilate carbohydrates or polyols. Based on phylogenetic analyses and physiological and biochemical characteristics, it is proposed that strain TU-16T (=LMG 23030T = CIP 108724T) represents the type strain of a novel species in a new genus, Tepidicella xavieri gen. nov., sp. nov.