Thermosipho activus sp. nov., a thermophilic, anaerobic, hydrolytic bacterium isolated from a deep-sea sample Podosokorskaya, Olga A. and Bonch-Osmolovskaya, Elizaveta A. and Godfroy, Anne and Gavrilov, Sergey N. and Beskorovaynaya, Daria A. and Sokolova, Tatyana G. and Kolganova, Tatyana V. and Toshchakov, Stepan V. and Kublanov, Ilya V.,, 64, 3307-3313 (2014), doi = https://doi.org/10.1099/ijs.0.063156-0, publicationName = Microbiology Society, issn = 1466-5026, abstract= A novel obligately anaerobic, extremely thermophilic, organotrophic bacterium, strain Rift-s3T, was isolated from a deep-sea sample containing Riftia pachyptila sheath from Guaymas Basin, Gulf of California. Cells of the novel isolate were rods, 0.3–0.8 µm in width and 1.5–10 µm in length, surrounded by a sheath-like structure (toga). Strain Rift-s3T grew at temperatures ranging from 44 to 75 °C, at pH 5.5 to 8.0, and with NaCl concentrations of 3 to 60 g l−1. Under optimum conditions (65 °C, pH 6.0, NaCl 25 g l−1), the doubling time was 30 min. The isolate was able to ferment mono-, oligo- and polysaccharides including cellulose, chitin, xylan and pectin, and proteins including β-keratins, casein and gelatin. Acetate, hydrogen and carbon dioxide were the main products of glucose fermentation. The G+C content of the DNA was 30 mol%. Phylogenetic analysis of 16S rRNA gene sequences showed the affiliation of strain Rift-s3T with the genus Thermosipho , with Thermosipho atlanticus Ob7T as the closest relative (96.5 % 16S rRNA gene sequence similarity). Based on the phylogenetic analysis and physiological properties of the novel isolate we propose a novel species of the genus Thermosipho , Thermosipho activus sp. nov., with Rift-s3T ( = DSM 26467T = VKM B-2803T) as the type strain., language=, type=