sp. nov., an obligately chemolithoautotrophic, sulphur-oxidizing bacterium isolated from a deep-sea sediment sample from the South China Sea.

A novel marine bacterium, designated strain B2, was isolated from a deep-sea sediment sample collected from the South China Sea. Cells were observed to be Gram-stain negative, motile and rod shaped with a single polar flagellum. B2 could grow at 10-45 °C (optimum, 35 °C), pH 4.5-9.0 (optimum, pH 7.0) and in the presence of 1.0-8.0 % (w/v) NaCl (optimum, 3.0%). The isolate grew chemolithoautotrophically with sulphide, elemental sulphur and thiosulphate as electron donors, carbon dioxide as the sole carbon source, and molecular oxygen as the sole electron acceptor. Molecular hydrogen did not support growth. The predominant fatty acids of B2 were Cω7, C and Cω7. The results of phylogenetic analysis based on 16S rRNA gene sequence indicated that B2 represented a member of the genus , with the highest similarity to the 16S rRNA gene sequences of NW8N (95.9 %), SN118 (95.7 %), 1-1N (95.6 %) and GO25 (95.4 %). Sequence similarities to other members of the genus were less than 95.0 %. In addition, the average nucleotide identity (ANI) value and digital DNA-DNA hybridization (dDDH) estimate between B2 and NW8N were 73.0 and 23.7 %, respectively. The size of the complete genome of B2 is 22 61 034 bp, with a DNA G+C content of 36.0 mol %. On the basis of the phenotypic, phylogenetic and genomic data presented here, strain B2 represent a novel species of the genus , for which the name sp. nov. is proposed, with the type strain B2 (=MCCC 1A14515=KCTC 15852).