Thermococcus piezophilus sp. nov., a novel hyperthermophilic and piezophilic archaeon with a broad pressure range for growth, isolated from a deepest hydrothermal vent at the Mid-Cayman Rise.

Abstract A novel strictly anaerobic, hyperthermophilic archaeon, designated strain CDGS T , was isolated from a deep-sea hydrothermal vent in the Cayman Trough at 4964 m water depth. The novel isolate is obligate anaerobe and grows chemoorganoheterotrophically with stimulation of growth by sulphur containing compounds. Its growth is optimal at 75 °C, pH 6.0 and under a pressure of 50 MPa. It possesses the broadest hydrostatic pressure range for growth that has ever been described for a microorganism. Its genomic DNA G + C content is 51.11 mol%. The novel isolate belongs to the genus Thermococcus . Phylogenetic analyses indicated that it is most closely related to Thermococcus barossii DSM17882 T based on its 16S rRNA gene sequence, and to ‘ Thermococcus onnurineus ’ NA1 based on its whole genome sequence. The average nucleotide identity scores with these strains are 77.66% for T. barossii and 84.84% for ‘ T. onnurineus ’, respectively. Based on the draft whole genome sequence and phenotypic characteristics, strain CDGS T is suggested to be separated into a novel species within the genus Thermococcus , with proposed name Thermococcus piezophilus (type strain CDGS T  = ATCC TSD-33 T  = UBOCC 3296 T ).