Thermococcus prieurii sp. nov., a hyperthermophilic archaeon isolated from a deep-sea hydrothermal vent

Abstract

A novel hyperthermophilic, anaerobic archaeon, strain Bio-pl-0405IT2T, was isolated from a hydrothermal chimney sample collected from the East Pacific Rise at 2700 m depth in the ‘Sarah Spring’ area (7° 25′ 24″ S 107° 47′ 66″ W). Cells were irregular, motile cocci (0.8–1.5 µm in diameter) and divided by constriction. Growth was observed at temperatures between 60 °C and 95 °C with an optimum at 80 °C. The pH range for growth was between pH 4.0 and pH 8.0 with an optimum around pH 7.0. Strain Bio-pl-0405IT2T grew at salt concentrations of 1–5 % (w/v) NaCl with an optimum at 2 %. The novel isolate grew by fermentation or sulphur respiration on a variety of organic compounds. It was a chemoorganoheterotrophic archaeon growing preferentially with yeast extract, peptone and tryptone as carbon and energy sources and sulphur and organic compounds as electron acceptors; it also grew on maltose and starch. Sulphur or l-cystine were required for growth and were reduced to hydrogen sulfide. The strain was resistant to rifampicin, chloramphenicol, vancomycin and kanamycin (all at 100 µg ml−1) but was sensitive to tetracycline. The G+C content of its genomic DNA was 53.6 mol%. Phylogenetic analysis of the almost complete 16S rRNA gene sequence (1450 bp) of strain Bio-pl-0405IT2T showed that the novel isolate belonged to the genus Thermococcus . DNA–DNA hybridization values with the two closest relatives Thermococcus hydrothermalis AL662T and Thermococcus celer JCM 8558T were below the threshold value of 70 %. On the basis of the physiological and genotypic distinctness, we propose a novel species, Thermococcus prieurii sp. nov. The type strain is Bio-pl-0405IT2T ( = CSUR P577T = JCM 16307T).