%0 Journal Article %A Pikuta, Elena V. %A Marsic, Damien %A Itoh, Takashi %A Bej, Asim K. %A Tang, Jane %A Whitman, William B. %A Ng, Joseph D. %A Garriott, Owen K. %A Hoover, Richard B. %T Thermococcus thioreducens sp. nov., a novel hyperthermophilic, obligately sulfur-reducing archaeon from a deep-sea hydrothermal vent %D 2007 %J International Journal of Systematic and Evolutionary Microbiology, %V 57 %N 7 %P 1612-1618 %@ 1466-5034 %R https://doi.org/10.1099/ijs.0.65057-0 %K TEM, transmission electron microscopy %I Microbiology Society, %X A hyperthermophilic, sulfur-reducing, organo-heterotrophic archaeon, strain OGL-20PT, was isolated from ‘black smoker’ chimney material from the Rainbow hydrothermal vent site on the Mid-Atlantic Ridge (36.2°N, 33.9°W). The cells of strain OGL-20PT have an irregular coccoid shape and are motile with a single flagellum. Growth was observed within a pH range of 5.0−8.5 (optimum pH 7.0), an NaCl concentration range of 1–5 % (w/v) (optimum 3 %) and a temperature range of 55–94 °C (optimum 83–85 °C). The novel isolate is strictly anaerobic and obligately dependent upon elemental sulfur as an electron acceptor, but it does not reduce sulfate, sulfite, thiosulfate, Fe(III) or nitrate. Proteolysis products (peptone, bacto-tryptone, Casamino acids and yeast extract) are utilized as substrates during sulfur reduction. Strain OGL-20PT is resistant to ampicillin, chloramphenicol, kanamycin and gentamicin, but sensitive to tetracycline and rifampicin. The G+C content of the DNA is 52.9 mol%. The 16S rRNA gene sequence analysis revealed that strain OGL-20PT is closely related to Thermococcus coalescens and related species, but no significant homology by DNA–DNA hybridization was observed between those species and the new isolate. On the basis of physiological and molecular properties of the new isolate, we conclude that strain OGL-20PT represents a new separate species within the genus Thermococcus, for which we propose the name Thermococcus thioreducens sp. nov. The type strain is OGL-20PT (=JCM 12859T=DSM 14981T=ATCC BAA-394T). %U https://www.microbiologyresearch.org/content/journal/ijsem/10.1099/ijs.0.65057-0