Methanocaldococcus jannaschii DSM 2661

M. jannaschii was the first Archaea to have it's genome sequenced, which opened the doors for comparison between the genomes of the three domains. It was originally located from a sediment sample collected from the sea floor at the base of a "white smoker" chimney on the East Pacific Rise.Methanocaldococcus jannaschii was formally in the genus Methanococcus, but due to its ability to grow in high temperatures it was re-classified. There were a few thermophilic species in Methanococcus that were reorganized, and this reorganization was supported by a low 16S rRNA sequence similarity between the thermophilics and mesophilics. The species left in Methanococcus are mesophilic and are related on the genus level by close DNA reassociation levels.No difference is noted in the G + C content of thermophilics and mesophilics of Methanococcus. However, there is a difference in the proteins. The thermophilic proteins have higher residue volume, higher residue hydrophobicity, more charged amino acids, and fewer uncharged polar residues than the mesophilic proteins.This autotrophic organism is strictly anaerobic and gets it's energy by the reduction of CO2 with H2 to generate methane. In addition to it's anabolic pathway, it also contains several scavenging molecules that most likely play a role in importing small organic compounds such as amino acids. Although Methanococcus spp. have a nifH-like gene they cannot fix N2, with the exception of M. maripaludis that can.Structurally the species consist of having two bundles of flagella at the same cellular pole along with no cell membrane, but a thin S-layer covering the plasma membrane. They are cocci in shape, about 1.0 microns in diameter, and are Gram stain negative.M. jannaschii can grow in habitats with pressure up to more than 200 atm and a temperature range between 48 and 94oC, with an optimum growth temperature being 85oC.(From http://microbewiki.kenyon.edu/index.php/Methanocaldococcus) (MicrobeWiki: Methanocaldococcus)