Methanopyrus is a genus of methanogen, with a single described species, Methanopyrus kandleri. It is a rod-shaped hyperthermophile, discovered on the wall of a black smoker from the Gulf of California at a depth of 2,000 m, at temperatures of 84–110 °C. Strain 116 was discovered in black smoker fluid of the Kairei hydrothermal field; it can survive and reproduce at 122 °C. M. kandleri also requires a high ionic concentration (>1 M) in order for growth and cellular activity. Due to the species' high resilience and extreme environment, M. kandleri is also classified as an extremophile. It lives in a hydrogen–carbon dioxide rich environment, and like other methanogens reduces the latter to methane. It is placed among the Euryarchaeota, in its own class.

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