Methanocaldococcus sp. FS406-22 is an archaea in the genus Methanocaldococcus. It is an anaerobic, piezophilic, diazotrophic, hyperthermophilic marine archaeon. This strain is notable for fixing nitrogen at the highest known temperature of nitrogen fixers recorded to date. The 16S rRNA gene of Methanocaldococcus sp. FS406-22, is almost 100% similar to that of Methanocaldococcus jannaschii, a non-nitrogen fixer.
Discovery and isolation
Methanocaldococcus sp. FS406-22 was isolated from deep-sea hydrothermal vent fluid. Hydrothermal vents are located on the ocean floor where plates are moving tectonically apart, for example volcano sites and by mid ocean ridges. These mid ocean ridges provide a large supply of food for aquatic marine animals. The particular vent that strain FS406-22 was isolated from, is located on the Juan de Fuca Ridge in the Pacific Ocean near volcanic activity. Mausmi P. Mehta and John A. Baross isolated strain FS406-22 in September 2004 during the New Millennium Observatory cruise. The Thomas G. Thompson vessel made this cruise possible and journeyed off to the Axial Volcano. A remotely operated vehicle (ROPOS) sampled vent fluid from marker 113 using a hydrothermal fluid and particle sampler (HFPS). Marker 113 is a vent located at 1525 meters deep in the southeast corner of the caldera. This vent was active before the last eruption of Axial Volcano in January 1998.
Characteristics
Ecology
Methanocaldococcus sp. FS406-22 is a deep sea marine Archean. It is a hyperthermophilic methanogen that fixes nitrogen. Strain FS405-22 grows at an optimal temperature of 92 °C, allowing it to thrive near volcanoes. Strain FS406-22 prefers to inhabit specifically hydrothermal vents on the deep sea floor. Lastly, this marine archaean does not sporulate.
Morphology
This particular strain of Methanocaldococcus is cocci in shape. FS406-22 is gram negative and is not pathogenic to humans. Strain FS406-22 is a free-living marine archaean and motile via flagella.
Physiology and metabolism
Methanocaldococcus sp. FS406-22 is an anaerobic marine archaean that is able to fix nitrogen at extreme depths. Being a hyperthermophilic extremophile, it lives in an extremely hot environment for example, a hydrothermal vent, which can range anywhere from 75 °C to 110 °C. Strain FS406-22 is also a piezophilic, diazotrophic, lithotroph. It has an anaerobic metabolism, nitrogen-fixing metabolism, and is methanogenic. The electron acceptors consist of carbon dioxide, acetic acid, and nitrate. The electron donors are glutamine and carboxylic groups.
Genome
Its genome size is 1.77 Million base pairs long and contains 1,893 protein-coding genes. In addition to these protein coding genes, Methanocaldococcus sp. FS406-22 has 36 pseudogenes and a total of 23 CRISPR loci. This strain has the highest number of CRISPR loci of all sequenced isolates to date. It also has a GC-content of 32.04%.
Phylogeny
The 16S rRNA gene of Methanocaldococcus sp. FS406-22, is almost 100% similar to that of Methanocaldococcus jannaschii DSM 2661. The only difference being that Methanocaldococcus sp. FS406-22 is a hyperthermophilic nitrogen fixing archaea and Methanocaldococcus jannaschii DSM 2661 is unable to fix nitrogen. Other related species and strains of Methanocaldococcus that reside in the same Order include: Methanococcus aeolicus, Methanocaldococcus fervens, Methanotorris igneus, Methanocaldococcus infernus, Methanocaldococcus jannaschii, Methanococcus maripaludis, Methanothermococcus okinawensis, Methanococcus vannielii, Methanococcus voltae, and Methanocaldococcus vulcanius.
