A novel group of abyssal methanogenic archaebacteria (Methanopyrus ) growing at 110 degree C

The organisms with the highest growth temperature known so far are members of the archaebacterial genus Pyrodictium . These anaerobic sulphur reducers thrive at temperatures of up to 110 degree C within a shallow hydrothermal system off Vulcano, Italy. The authors have now isolated a novel group of methanogenic archaebacteria growing at least at 110 degree C from sediment samples taken by the research submersible Alvin at the Guaymas Basin hot vents (Gulf of California). This finding demonstrates the unexpected biogenic methanogenesis at temperatures above 100 degree C, and, in view of biogeochemistry at temperatures above 100 degree C, and, in view of biogeochemistry, could explain isotope discrimination at temperatures that were thought to be unfavourable for biological methanogenesis.