Description of Oceanispirochaeta sediminicola gen. nov., sp. nov., an obligately anaerobic bacterium isolated from coastal marine sediments, and reclassification of Spirochaeta litoralis as Oceanispirochaeta litoralis comb. nov.

An obligately anaerobic spirochaete (strain SY2T) was isolated from coastal marine sediments of Tongyeong-Si, South Korea. Strain SY2T was helical-shaped and Gram-stain-negative. Strain SY2T was able to grow at 10-40 °C (optima, 25-30 °C), pH 6.3-8.8 (optima, pH 7.0-8.0) and with 1-7 % (optimum, 2-3 %) NaCl concentration. Strain SY2T was negative for catalase and oxidase activity. The major end-products of glucose fermentation were acetate, ethanol, hydrogen and carbon dioxide. C14 : 0, C16 : 0, iso-C15 : 0, iso-C14 : 0 3-OH, iso-C15 : 1 H/C13 : 0 3-OH and iso-C17 : 1ω9c were predominant fatty acids (>5 %) with minor amounts (<5 %) of C18 : 0, iso-C13 : 0, iso-C17 : 0, iso-C17 : 1/anteiso-C17 : 1 B and C16 : 1ω6c/C16 : 1ω7c. Diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine were major polar lipids. The genomic DNA G+C content was 53.5 mol%. 16S rRNA gene sequence comparisons indicated that strain SY2T represents a member of the family Spirochaetaceae in the phylum Spirochaetes. Strain SY2T has a sequence similarity of 95.1 % with Spirochaeta litoralis R1T and <90.1 % with other members of the genus Spirochaeta. Distinct morphological, physiological and genotypic differences from the previously described taxa support the classification of strain SY2T as a representative of a novel genus and species in the family Spirochaetaceae, for which the name Oceanispirochaeta sediminicola gen. nov., sp. nov. is proposed. The type strain is SY2T (=KEMB 3001-381T=DSM 104770T=KCTC 15593T). Reclassification of Spirochaeta litoralis as Oceanispirochaeta litoralis comb. nov. is also proposed based on polyphasic taxonomic analyses.