Thiofaba tepidiphila gen. nov., sp. nov., a novel obligately chemolithoautotrophic, sulfur-oxidizing bacterium of the Gammaproteobacteria isolated from a hot spring.

A novel obligately chemolithoautotrophic, sulfur-oxidizing bacterium designated strain BDA453T was isolated from a hot spring in Fukushima prefecture, Japan. The cells were short-rod-shaped and possessed an inclusion, a Gram-negative type cell wall and a single polar flagellum. Strain BDA453T grew by sulfur-oxidizing respiration with thiosulfate, elemental sulfur, sulfide and tetrathionate as electron donors and used only carbon dioxide as a carbon source. The optimum growth conditions were 45 degrees C, pH 6.5 and the absence of NaCl. Analysis of the 16S rRNA gene revealed that the isolate was a member of the Gammaproteobacteria and related to the genera Halothiobacillus and Thiovirga in the family Halothiobacillaceae. However, the phylogenetic tree constructed using 16S rRNA gene sequences showed that strain BDA453T was distant from any other known bacteria with sequence similarities of less than 90 %. On the basis of phenotypic features and phylogenetic analysis, strain BDA453T is considered to represent a novel species of a new genus within the family Halothiobacillaceae, for which the name Thiofaba tepidiphila gen. nov., sp. nov. is proposed. The type strain of Thiofaba tepidiphila is BDA453T (=NBRC 103218T=DSM 19618T).