sp. nov., an anaerobic bacterium isolated from marine sediment.

A novel bacterium, strain SH18-1, was isolated from marine sediment collected near Sado Island in the Sea of Japan. This strain was strictly anaerobic, Gram-stain-negative, non-spore-forming, rod-shaped, motile, and mesophilic. It grew at 15-40 °C (optimum, 30-35 °C), at a NaCl concentration of 0.2-5.0 % (w/v; optimum, 1.5-2.5 %), and at pH 5.5-8.5 (optimum, pH 7.0). Results of 16S rRNA gene phylogenetic analysis showed a similarity value of 97.49 % between strain SH18-1 and Ra1766G1, which was the most closely related species. The genome size of strain SH18-1 was 5.71 Mb and its G+C content was 30.2 mol%. Genome sequence analyses for comparison between strain SH18-1 and Ra1766G1 showed values lower than the threshold for species demarcation determined using the Genome-to-Genome Distance Calculator and the Average Nucleotide Identity Calculator. Elemental sulphur, sulphate, thiosulphate, sulphite, fumarate, nitrate, and nitrite were not used as terminal electron acceptors. The major fatty acids in strain SH18-1 were iso-C, anteiso-C, and C, and the detected polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphoglycolipid, glycolipid, three unidentified phospholipids, and one unidentified polar lipid. From these results, strain SH18-1 (=NBRC 115488=DSM 114058) is suggested to represent a novel species of the genus and the name sp. nov. is proposed.