Kosmotoga pacifica sp. nov., a thermophilic chemoorganoheterotrophic bacterium isolated from an East Pacific hydrothermal sediment

A novel strictly anaerobic thermophilic heterotrophic bacterium, strain SLHLJ1^T, was isolated from a Pacific hydrothermal sediment. Cells were Gram-negative coccobacilli (approximately 1.0 × 0.6 μm) with a toga. It grew at temperatures between 33 and 78 °C (optimum 70 °C). Elemental sulphur and l-cystine stimulated its growth. It contained C_16:0, C_16:1 ω11c, C_18:0 and C_18:1 ω9c as major fatty acids (>5 %), 3 phospholipids and 2 glycolipids as polar lipids. Its DNA G+C content was 43.7 mol%. Phylogenetic analyses based on 16S rRNA gene sequences placed strain SLHLJ1^T within the family Thermotogaceae. The novel isolate was most closely related to Kosmotoga arenicorallina (97.93 % 16S rRNA gene sequence similarity), K. olearia (92.43 %) and K. shengliensis (92.17 %). On the basis of phenotypic, chemotaxonomic and phylogenetic comparisons with its closest relatives, we propose its assignment to a novel species of the genus Kosmotoga. The name Kosmotoga pacifica sp. nov. is proposed with strain SLHLJ1^T (=DSM 26965^T = JCM 19180^T = UBOCC 3254^T) as the type species.