Thermococci

Thermococci
Thermococcus gammatolerans
Scientific classification
Domain:	Archaea
Kingdom:	Methanobacteriati
Phylum:	Methanobacteriota
Class:	Thermococci Zillig and Reysenbach 2002 [1]
Orders
Thermococcales
Synonyms
"Methanofastidiosia" corrig. Nobu et al. 2016 Protoarchaea Cavalier-Smith 2002 "Thermococcia" Oren, Parte & Garrity 2016

Schematic diagram of the Thermococcus gammatolerans cell pictured above.

Pyrococcus furiosus

Thermococci is a class of microbes within the Euryarchaeota. ^[2]

They live in extremely hot environments, such as hydrothermal vents, ^[3] and their optimal optimal growth temperatures tend to be around 75 to 85°C. ^[4] Thermococcus and Pyrococcus (literally "balls of fire") are both obligately anaerobic chemoorganotrophs.

Thermococcus prefers 70–95 °C and Pyrococcus 70-100 °C. Palaeococcus helgesonii , recently discovered in the Tyrrhenian Sea, is an aerobic chemoheterotrophic that grows at temperatures of 45–85 °C with an optimal temperature of 80 °C. Thermococcus gammatolerans sp. nov. was recently discovered in the Guaymas Basin, and it grows at temperatures from 55 to 95 °C with an optimal temperature around 88 °C with an optimal pH of 6. It has pronounced radioresistance and can survive gamma radiation at 30 kGy. ^[5]

Thermococcus grows on organic substrates where there is a higher capacity of elemental sulfur. This archaeon mostly grows between temperatures 60–100 degrees Celsius. The average temperature where they thrive is around 85 degrees Celsius.

The DNA structure has a cicular genome with around 2,353 coding sequence, and 2,306 are identified.

Taxonomy

This class encompasses the hyperthermophilic ^{[6] [7]} members of Methanobacteriota that have a sulfur-based anaerobic respiration. ^[7] There is only one widely recognized order within Thermococci, Thermococcales. ^[8] Another proposed but not yet widely accepted order is Candidatus Methanofastidiosales. ^[9] Thermococcales encompasses the family Thermococcaceae, which is composed of three genus: Palaeococcus, Pyrococcus and Thermococcus. ^[8] Palaeococcus encompasses 3 species, while Pyrococcus and Thermococcus encompass 24 and 179 species, respectively. ^[10]

See also

• List of Archaea genera

References

1. A.C. Parte; et al. "Thermococci". List of Prokaryotic names with Standing in Nomenclature (LPSN). Retrieved 2025-02-28.
2. See the NCBI webpage on Thermococci. Data extracted from the "NCBI taxonomy resources". National Center for Biotechnology Information . Retrieved 2007-03-19.
3. Price, Mark Thomas; Fullerton, Heather; Moyer, Craig Lee (2015-09-24). "Biogeography and evolution of Thermococcus isolates from hydrothermal vent systems of the Pacific". Frontiers in Microbiology. 6. doi: 10.3389/fmicb.2015.00968 . ISSN   1664-302X. PMC   4585236 .
4. Lamosa, Pedro; Martins, Lígia O.; Da Costa, Milton S.; Santos, Helena (October 1998). "Effects of Temperature, Salinity, and Medium Composition on Compatible Solute Accumulation byThermococcus spp". Applied and Environmental Microbiology. 64 (10): 3591–3598. Bibcode:1998ApEnM..64.3591L. doi:10.1128/AEM.64.10.3591-3598.1998. PMC   106469 . PMID   9758772.
5. "Airspade" . Retrieved 13 June 2023.
6. Cavalier-Smith, T (2002-01-01). "The neomuran origin of archaebacteria, the negibacterial root of the universal tree and bacterial megaclassification" . International Journal of Systematic and Evolutionary Microbiology. 52 (1): 7–76. doi:10.1099/00207713-52-1-7. ISSN   1466-5026. PMID   11837318.
7. Gao, Beile; Gupta, Radhey S. (2007-03-29). "Phylogenomic analysis of proteins that are distinctive of Archaea and its main subgroups and the origin of methanogenesis". BMC Genomics. 8: 86. doi: 10.1186/1471-2164-8-86 . ISSN   1471-2164. PMC   1852104 . PMID   17394648.
8. "Explore the Taxonomic Tree | FWS.gov". www.fws.gov. Retrieved 2025-06-26.
9. "Order: Methanofastidiosales". lpsn.dsmz.de. Retrieved 2025-06-30.
10. "Taxonomy Browser". NCBI. Retrieved 2025-06-26.

Further reading

• Marguet, Evelyne; Gaudin, Marie; Gauliard, Emilie; Fourquaux, Isabelle; le Blond du Plouy, Stephane; Matsui, Ikuo; Forterre, Patrick (2013). "Membrane vesicles, nanopods and/or nanotubes produced by hyperthermophilic archaea of the genus Thermococcus". Biochemical Society Transactions. 41 (1): 436–442. doi:10.1042/BST20120293. PMID   23356325.
• Woese, CR; Kandler O; Wheelis ML (1990). "Towards a natural system of organisms: proposal for the domains Archaea, Bacteria, and Eucarya". Proc. Natl. Acad. Sci. USA. 87 (12): 4576–4579. Bibcode:1990PNAS...87.4576W. doi: 10.1073/pnas.87.12.4576 . PMC   54159 . PMID   2112744.
• Zillig W; Reysenbach AL (2001). "Class IV (sic) [V]. Thermococci class. nov.". In DR Boone; RW Castenholz (eds.). Bergey's Manual of Systematic Bacteriology Volume 1: The Archaea and the deeply branching and phototrophic Bacteria (2nd ed.). New York: Springer Verlag. pp.  169. ISBN   978-0-387-98771-2.
• Garrity GM; Holt JG (2001). "Phylum AII. Euryarchaeota phy. nov.". In DR Boone; RW Castenholz (eds.). Bergey's Manual of Systematic Bacteriology Volume 1: The Archaea and the deeply branching and phototrophic Bacteria (2nd ed.). New York: Springer Verlag. pp.  169. ISBN   978-0-387-98771-2.