Thiomicrospira hydrogeniphila sp. nov., an aerobic, hydrogen- and sulfur-oxidizing chemolithoautotroph isolated from a seawater tank containing a block of beef tallow.

A moderately psychrophilic, aerobic, hydrogen- and sulfur-oxidizing bacterium, designated strain MAS2T, was isolated from a tank containing coastal seawater from Tokyo Bay and a block of beef tallow added as organic material. Growth occurred under aerobic chemolithoautotrophic conditions in the presence of molecular hydrogen, thiosulfate, tetrathionate, elemental sulfur or sulfide as the sole energy source and bicarbonate as a carbon source. The isolate represented a Gram-staining-negative rod with a single polar flagellum and grew in artificial seawater medium with thiosulfate at 2-40 °C (optimum 30 °C). The isolate grew in media with thiosulfate at Na+ concentrations between 30 and 1380 mM (optimum 270 mM). MAS2T possessed C16 : 0, C16 : 1 and C18 : 1 as the major fatty acids. The G+C content of the genomic DNA was 39.6 mol%. The 16S rRNA gene sequence similarity analysis showed that the isolate represented a member of the genus Thiomicrospira within the class Gammaproteobacteria and was most closely related to Thiomicrospira frisia JB-A2T. On the basis of phenotypic and molecular properties, the isolate represents a novel species of the genus Thiomicrospira, for which the name Thiomicrospira hydrogeniphila sp. nov. is proposed (type strain, MAS2T=JCM 30760T=DSM 100274T).