Methanopyrus is a rod-shaped hyperthermophilic methanogen that has been isolated from sediments near submarine hydrothermal vents and from the walls of "black smoker" hydrothermal vent chimneys. Methanopyrus occupies a unique phylogenetic position on the tree of Archaea; it is one of the most ancient (least derived) of all known hyperthermophilic Archaea and shares phontypic properties with both the hyperthermophiles (growth temperature maximum, 110°C) and the methanogens (it carries out the reaction of 4H2 + CO2 -> CH4 + 2H2O).
Methanopyrus produces methane from H2 + CO2 only and grows rapidly (generation time less than 1 h) at its temperature optimum of 100°C. Unlike mesophilic methanogens, however, cells of Methanopyrus have large amounts of the glycolytic derivative, cyclic 2,3-diphosphoglycerate, dissolved in the cytoplasm. This compound, present at more than 1 M concentration in Methanopyrus, is thought to function as a thermostabilizing agent to prevent denaturation of enzymes and DNA inside the cell. In addition, Methanopyrus contains a type of membrane lipid found in no other known organism; this ether lipid is an unsaturated form of the otherwise saturated dibiphytanyl tetraethers found in other hyperthermophiles.
The discovery of Methanopyrus may explain the origin of hydocarbon-like materials in hot oceanic sediments previously thought to be too hot to support biogenic methanogenesis. In addition, at the depth at which Methanopyrus was found, approximately 2000 m, water remains liquid at temperatures up to 350°C, suggesting that other hyperthermophilic methanogens may exist capable of growth at 110°C or at perhaps even higher
Taken from the text Brock Biology of Microorganisms (10th ed.). Madigan, M.T., Martinko, J.M., and Parker, J. 2003. Prentice Hall. 459p.