|
''Thermococcus gammatolerans'' is an archaea extremophile and the most radiation-resistant organism known to exist. Discovered in 2003 in a submarine hydrothermal vent in the Guaymas Basin about 2,000 meters deep off the coast of California, ''Thermococcus gammatolerans'' thrives in temperatures between 55–95 °C with an optimum development at approximately 88 °C. The optimal growth pH is 6, favoring the presence of sulfur (S), which is reduced to hydrogen sulfide (). It is the organism with the strongest known resistance to radiation, supporting a radiation of gamma rays from 30,000 gray (Gy).〔Jolivet E, L'Haridon S, Corre E, Forterre P, Prieur D. 2003 "Thermococcus gammatolerans sp. nov., a hyperthermophilic archaeon from a deep-sea hydrothermal vent that resists ionizing radiation. " PMID 12807211 ]〕 Along with the genera ''Palaeococcus'' and ''Pyrococcus'', ''Thermococcus'' belongs to the Thermococcaceae family, sole family of the Thermococci (called "Protoarchaea" by Cavalier-Smith), a class in the phylum Euryarchaeota of Archaea. ''Thermococcus'' species live in extremely hot environments such as hydrothermal vents with a growth optimum temperature above 80 °C. ''Thermococcus'' and ''Pyrococcus'' (literally "ball of fire") are both chemoorganotrophic anaerobic required. ''Thermococcus'' spp. prefer 70–95 °C, whereas ''Pyrococcus'' prefer 70–100 °C. The resistance to ionizing radiation of ''T. gammatolerans'' is enormous. While a dose of 5 Gy is sufficient to kill a human, and a dose of 60 Gy is able to kill all cells in a colony of ''E. coli'', ''Thermococcus gammatolerans'' can withstand doses of up to 30,000 Gy, and an instantaneous dose of up to 5,000 Gy with no loss of viability. == History == ''Thermococcus gammatolerans'' was discovered in 2003 in samples collected from a hydrothermal chimney at the Guaymas Basin about 2,000 meters deep off the coast of California (27° 1' N, 111° 24' W). 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Thermococcus gammatolerans」の詳細全文を読む スポンサード リンク
|