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A thermophile is an organism—a type of extremophile—that thrives at relatively high temperatures, between 41 and 122 °C. Many thermophiles are archaea, though they can be bacteria. Thermophilic eubacteria are suggested to have been among the earliest bacteria.
A hydrothermal vent is a fissure on the seafloor from which geothermally heated water discharges. Hydrothermal vents are commonly found near volcanically active places, areas where tectonic plates are moving apart at spreading centers, ocean basins, and hotspots. Hydrothermal deposits are rocks and mineral ore deposits formed by the action of hydrothermal vents.
A hyperthermophile is an organism that thrives in extremely hot environments—from 60 °C upwards. An optimal temperature for the existence of hyperthermophiles is often above 80 °C. Hyperthermophiles are often within the domain Archaea, although some bacteria are also able to tolerate extreme temperatures. Some of these bacteria are able to live at temperatures greater than 100 °C, deep in the ocean where high pressures increase the boiling point of water. Many hyperthermophiles are also able to withstand other environmental extremes, such as high acidity or high radiation levels. Hyperthermophiles are a subset of extremophiles. Their existence may support the possibility of extraterrestrial life, showing that life can thrive in environmental extremes.
Archaeoglobus is a genus of the phylum Euryarchaeota. Archaeoglobus can be found in high-temperature oil fields where they may contribute to oil field souring.
Geoglobus is a hyperthermophilic member of the Archaeoglobaceae within the Euryarchaeota. It consists of two species, the first, G. ahangari, isolated from the Guaymas Basin hydrothermal system located deep within the Gulf of California. As a hyperthermophile, it grows best at a temperature of 88 °C and cannot grow at temperatures below 65 °C or above 90 °C. It possess an S-layer cell wall and a single flagellum. G. ahangari is an anaerobe, using poorly soluble ferric iron (Fe3+) as a terminal electron acceptor. It can grow either autotrophically using hydrogen gas (H2) or heterotrophically using a large number of organic compounds, including several types of fatty acids, as energy sources. G. ahangari was the first archaeon isolated capable of using hydrogen gas coupled to iron reduction as an energy source and the first anaerobe isolated capable of using long-chain fatty acids as an energy source.
Archaeal Richmond Mine acidophilic nanoorganisms (ARMAN) were first discovered in an extremely acidic mine located in northern California by Brett Baker in Jill Banfield's laboratory at the University of California Berkeley. These novel groups of archaea named ARMAN-1, ARMAN-2, and ARMAN-3 were missed by previous PCR-based surveys of the mine community because the ARMANs have several mismatches with commonly used PCR primers for 16S rRNA genes. Baker et al. detected them in a later study using shotgun sequencing of the community. The three groups were originally thought to represent three unique lineages deeply branched within the Euryarchaeota, a subgroup of the Archaea. However, based on a more complete archaeal genomic tree, they were assigned to a new superphylum named DPANN. The ARMAN groups now comprise deeply divergent phyla named Micrarchaeota and Parvarchaeota. Their 16S rRNA genes differ by as much as 17% between the three groups. Prior to their discovery, all of the Archaea shown to be associated with Iron Mountain belonged to the order Thermoplasmatales.
In taxonomy, Thermococcus is a genus of thermophilic Archaea in the family the Thermococcaceae.
Aciduliprofundum is a genus of the Euryarchaeota.
Pyrococcus abyssi is a hyperthermophilic archaeon isolated from a deep-sea hydrothermal vent in the North Fiji Basin at 2,000 metres (6,600 ft). It is anaerobic, sulfur-metabolizing, gram-negative, coccus-shaped and highly motile. Its optimum growth temperature is 96 °C (205 °F). Its type strain is GE5. Pyrococcus abyssi has been used as a model organism in studies of DNA polymerase. This species can also grow at high cell densities in bioreactors.
Thermoplasma volcanium is a moderate thermoacidophilic archaea isolated from acidic hydrothermal vents and solfatara fields. It contains no cell wall and is motile. It is a facultative anaerobic chemoorganoheterotroph. No previous phylogenetic classifications have been made for this organism. Thermoplasma volcanium reproduces asexually via binary fission and is nonpathogenic.
Sulfolobus metallicus is a coccoid shaped thermophilic archaeon. It is a strict chemolithoautotroph gaining energy by oxidation of sulphur and sulphidic ores into sulfuric acid. Its type strain is Kra 23. It has many uses that take advantage of its ability to grow on metal media under acidic and hot environments.
Thermococcus barophilus is a barophilic and hyperthermophilic archaeon isolated from a deep-sea hydrothermal vent. It is anaerobic and sulfur-metabolising, with type strain MPT.
Thermococcus hydrothermalis is a hyperthermophilic archaeon. It is strictly anaerobic and coccus-shaped, and its cells range from 0.8 to 2.0 μm in diameter, with type strain AL662T. It was isolated from a hydrothermal vent in the East Pacific Rise. This species is notable for its α-glucosidase, which functions optimally at a temperature of 110 °C.
Lokiarchaeota is a proposed phylum of the Archaea. The phylum includes all members of the group previously named Deep Sea Archaeal Group (DSAG), also known as Marine Benthic Group B (MBG-B). A phylogenetic analysis disclosed a monophyletic grouping of the Lokiarchaeota with the eukaryotes. The analysis revealed several genes with cell membrane-related functions. The presence of such genes support the hypothesis of an archaeal host for the emergence of the eukaryotes; the eocyte-like scenarios.
Methanocaldococcussp. 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.
Acidilobus saccharovorans is a thermoacidophilic species of anaerobic archaea. The species was originally described in 2009 after being isolated from hot springs in Kamchatka.
Aciduliprofundum boonei is an obligate thermoacidophilic archaea belonging to the phylum Euryarchaeota. Isolated from acidic hydrothermal vent environments, A. boonei is the first cultured representative of a biogeochemically significant clade of thermoacidophilic archaea known as the “Deep-Sea Hydrothermal Vent Euryarchaeota 2 (DHVE2)”.
Hippea alviniae is a thermoacidophilic and obligately anaerobic bacterium from the genus of Hippea which has been isolated from a hydrothermal vent from the East Pacific Rise.
The hydrothermal vent microbial community includes all unicellular organisms that live and reproduce in a chemically distinct area around hydrothermal vents. These include organisms in the microbial mat, free floating cells, or bacteria in an endosymbiotic relationship with animals. Chemolithoautotrophic bacteria derive nutrients and energy from the geological activity at Hydrothermal vents to fix carbon into organic forms. Viruses are also a part of the hydrothermal vent microbial community and their influence on the microbial ecology in these ecosystems is a burgeoning field of research.
References
- ↑ Flores G, Wagner I, Liu Y, Reysenbach AL. 2012. Distribution, abundance, and diversity patterns of thermoacidophilic "deep-sea hydrothermal vent euryarchaeotha 2. 3:1-17
- ↑ Reysenbach AL, Liu Y, Banta A, Beveridge T, Kirshtein J, Schouten S, Tivey M, Von Damm K, Voytek M 2006. A ubiquitous thermoacidophilic archaeon from deep-sea hydrothermal vents. Nature. 442:444-447