RT Journal Article SR Electronic(1) A1 Birrien, Jean-Louis A1 Zeng, Xiang A1 Jebbar, Mohamed A1 Cambon-Bonavita, Marie-Anne A1 Quérellou, Joël A1 Oger, Philippe A1 Bienvenu, Nadège A1 Xiao, Xiang A1 Prieur, DanielYR 2011 T1 Pyrococcus yayanosii sp. nov., an obligate piezophilic hyperthermophilic archaeon isolated from a deep-sea hydrothermal vent JF International Journal of Systematic and Evolutionary Microbiology, VO 61 IS 12 SP 2827 OP 2881 DO https://doi.org/10.1099/ijs.0.024653-0 PB Microbiology Society, SN 1466-5034, AB An obligate piezophilic anaerobic hyperthermophilic archaeon, designated strain CH1T, was isolated from a hydrothermal vent site named ‘Ashadze’, which is located on the Mid-Atlantic Ridge at a depth of 4100 m. Enrichment and isolation of the strain were carried out at 95 °C under a hydrostatic pressure of 42 MPa. Cells of strain CH1T were highly motile irregular cocci with a diameter of ~1–1.5 µm. Growth was recorded at 80–108 °C (optimum 98 °C) and at pressures of 20–120 MPa (optimum 52 MPa). No growth was observed under atmospheric pressures at 60–110 °C. Growth was observed at pH 6.0–9.5 (optimum 7.5–8.0) and in 2.5–5.5 % (w/v) NaCl (optimum 3.5 %). Strain CH1T was strictly anaerobic and grew on complex proteinaceous substrates, such as yeast extract, Peptone, and casein, as well as on sucrose, starch, chitin, pyruvate, acetate and glycerol without electron acceptors. The G+C content of the genomic DNA was 49.0±0.5 mol%. Analysis of 16S rRNA gene sequences revealed that strain CH1T belongs to the genus Pyrococcus. Based on its physiological properties and similarity levels between ribosomal proteins, strain CH1T represents a novel species, for which the name Pyrococcus yayanosii sp. nov. is proposed. The type strain is CH1T ( = JCM 16557). This strain is also available by request from the Souchothèque de Bretagne (catalogue LMBE) culture collection (collection no. 3310)., UL https://www.microbiologyresearch.org/content/journal/ijsem/10.1099/ijs.0.024653-0