Thiomicrorhabdus indica sp. nov., an obligately chemolithoautotrophic, sulfur-oxidizing bacterium isolated from a deep-sea hydrothermal vent environment.

A new mesophilic bacterium, designated strain 13-15AT, was isolated from the deep-sea water from the Carlsberg Ridge, northwestern Indian Ocean. Cells were short rods and motile with a single polar flagellum. Growth was observed in the presence of 85-1700 mM NaCl (optimum 680 mM), at 10-45 °C (optimum, 28 °C) and pH 5.0-9.0 (optimum, pH 7.0). The isolate was an obligate chemolithoautotroph capable of growth using thiosulfate, sulfide, elemental sulfur or tetrathionate as the sole energy source, carbon dioxide as the sole carbon source, and molecular oxygen as the sole electron acceptor. Molecular hydrogen did not support growth. The major fatty acids were C16 : 1 (45.0 %), C18 : 1 (22.5 %) and C16 : 0 (20.1 %). The G+C content of the genomic DNA was 41.6 mol%. The results of phylogenetic analysis based on 16S rRNA gene sequences showed that the novel isolate belonged to the genus Thiomicrorhabdus and was most closely related to Thiomicrorhabdus hydrogeniphila MAS2T (94.8 % sequence similarity). On the basis of the taxonomic data obtained in this study, strain 13-15AT represents a novel species of the genus Thiomicrorhabdus, for which the name Thiomicrorhabdus indica sp. nov. is proposed, with the type strain 13-15AT (=MCCC 1A13986T=KCTC 15750T).