Thermococcus gammatolerans

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Thermococcus gammatolerans
Thermococcus gammatolerans.jpg
Thermococcus gammatolerans
Scientific classification
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T. gammatolerans
Binomial name
Thermococcus gammatolerans
Jolivet , 2003

Thermococcus gammatolerans is an archaea extremophile and the most radiation-resistant organism known to exist.

Contents

As reported in 2003 the type strain EJ3T was taken from a submarine hydrothermal vent in the Guaymas Basin off the coast of Baja California at a depth of about 2,600  m by submersible Nautile during the 1991 Guaynaut cruise. Thermococcus gammatolerans thrives in temperatures between 55 and 95 °C with an optimum development around 88 °C. Its optimal growth pH is 6, favoring the presence of sulfur (S), which is reduced to hydrogen sulfide (H
2
S
). It is the organism with the strongest known resistance to radiation, supporting a radiation of gamma rays from 30,000 gray (Gy). [1]

Along with the genera Palaeococcus and Pyrococcus, Thermococcus belongs to the Thermococcaceae family, sole family of the Thermococci (called "Protoarchaea" by Cavalier-Smith), a class in the phylum Euryarchaeota of Archaea. [2] Thermococcus species live in extremely hot environments such as hydrothermal vents with a growth optimum temperature above 80 °C. Thermococcus and Pyrococcus (literally "ball of fire") are both chemoorganotrophic anaerobic required. Thermococcus spp. prefer 70–95 °C, whereas Pyrococcus species prefer 70–100 °C.

The resistance to ionizing radiation of T. gammatolerans is enormous. While a dose of 5 Gy is sufficient to kill a human, and a dose of 60 Gy is able to kill all cells in a colony of E. coli, Thermococcus gammatolerans can withstand doses up to 30,000 Gy, and an instantaneous dose up to 5,000 Gy with no loss of viability.

History

Thermococcus gammatolerans was discovered in 2003 in samples collected from a hydrothermal chimney at the Guaymas Basin about 2,000 m deep off the coast of California, (27° 1' N, 111° 24' W).

Mechanisms of resistance to radiation

Unlike other organisms, cell survival in T. gammatolerans is not altered by changing conditions in its growth phase, but the lack of ideal conditions and nutrients decreases its radioresistance. The system of chromosomal DNA repair shows that cells in stationary phase of growth reconstitute DNA more rapidly than cells in exponential growth phase. T. gammatolerans can slowly or quickly rebuild damaged chromosomes without loss of viability. [3]

Applications

A study has been conducted of its application to the development of new enzymatic markers that are resistant to high temperatures and their application in the study of carcinogenesis and the study of the development of mitochondrial diseases. DNA repair mechanisms of T. gammatolerans could be incorporated into the genome of higher species to improve DNA repair and reduce cellular aging.

Etymology

Thermococcus: Greek feminine noun thermê (θέρμη), [4] heat; Neo-Latin masculine noun coccus (from Greek masculine noun kokkos (κόκκος), [5] berry), coccus; new Latin masculine noun Thermococcus, coccus existing in hot environment. [6] gammatolerans: Gr. gamma (γάμμα), [7] referring to gamma rays; Latin participle adjective tolerans, tolerating; Neolatin participle adjective gammatolerans, referring to its ability to tolerate high levels of γ-rays. [6]

Related Research Articles

<span class="mw-page-title-main">Extremophile</span> Organisms capable of living in extreme environments

An extremophile is an organism that is able to live in extreme environments, i.e. environments with conditions approaching or expanding the limits of what known life can adapt to, such as extreme temperature, radiation, salinity, or pH level.

<span class="mw-page-title-main">Thermophile</span> Organism that thrives at relatively high temperatures

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 some of them are bacteria and fungi. Thermophilic eubacteria are suggested to have been among the earliest bacteria.

A hyperthermophile is an organism that thrives in extremely hot environments—from 60 °C (140 °F) upwards. An optimal temperature for the existence of hyperthermophiles is often above 80 °C (176 °F). 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.

Radioresistance is the level of ionizing radiation that organisms are able to withstand.

<i>Pyrococcus furiosus</i> Species of archaeon

Pyrococcus furiosus is a heterotrophic, strictly anaerobic, extremophilic, model species of archaea. It is classified as a hyperthermophile because it thrives best under extremely high temperatures, and is notable for having an optimum growth temperature of 100 °C. P. furiosus belongs to the Pyrococcus genus, most commonly found in extreme environmental conditions of hydrothermal vents. It is one of the few prokaryotic organisms that has enzymes containing tungsten, an element rarely found in biological molecules.

<span class="mw-page-title-main">Thermococci</span> Class of archaea

In taxonomy, the Thermococci are a class of microbes within the Euryarchaeota.

In taxonomy, Thermococcus is a genus of thermophilic Archaea in the family the Thermococcaceae.

Thermococcus litoralis is a species of Archaea that is found around deep-sea hydrothermal vents as well as shallow submarine thermal springs and oil wells. It is an anaerobic organotroph hyperthermophile that is between 0.5–3.0 μm (20–118 μin) in diameter. Like the other species in the order thermococcales, T. litoralis is an irregular hyperthermophile coccus that grows between 55–100 °C (131–212 °F). Unlike many other thermococci, T. litoralis is non-motile. Its cell wall consists only of a single S-layer that does not form hexagonal lattices. Additionally, while many thermococcales obligately use sulfur as an electron acceptor in metabolism, T. litoralis only needs sulfur to help stimulate growth, and can live without it. T. litoralis has recently been popularized by the scientific community for its ability to produce an alternative DNA polymerase to the commonly used Taq polymerase. The T. litoralis polymerase, dubbed the vent polymerase, has been shown to have a lower error rate than Taq but due to its proofreading 3’–5’ exonuclease abilities.

Thermococcus celer is a Gram-negative, spherical-shaped archaeon of the genus Thermococcus. The discovery of T. celer played an important role in rerooting the tree of life when T. celer was found to be more closely related to methanogenic Archaea than to other phenotypically similar thermophilic species. T. celer was the first archaeon discovered to house a circularized genome. Several type strains of T. celer have been identified: Vu13, ATCC 35543, and DSM 2476.

<span class="mw-page-title-main">Orders of magnitude (radiation)</span>

Recognized effects of higher acute radiation doses are described in more detail in the article on radiation poisoning. Although the International System of Units (SI) defines the sievert (Sv) as the unit of radiation dose equivalent, chronic radiation levels and standards are still often given in units of millirems (mrem), where 1 mrem equals 1/1,000 of a rem and 1 rem equals 0.01 Sv. Light radiation sickness begins at about 50–100 rad.

Macrococcus is a genus of Gram-positive cocci belonging to the family Staphylococcaceae. The genus was created in 1998.

Thermococcus kodakarensis is a species of thermophilic archaea. The type strain T. kodakarensis KOD1 is one of the best-studied members of the genus.

Pyrococcus horikoshii is a hyperthermophilic, anaerobic archaeon, first isolated from hydrothermal fluid samples obtained at the Okinawa Trough vents at a depth of 1,395 metres (4,577 ft). It is obligately heterotrophic, cells are irregular cocci with a tuft of flagella, growing optimally at 98 °C, sulphur greatly enhancing its growth.

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.

Thermococcus profundus is a hyperthermophilic archaeon isolated from a deep-sea hydrothermal vent. It is coccoid-shaped with 1–2 μm in diameter, designated as strain DT5432.

Thermococcus chitonophagus is a chitin-degrading, hyperthermophilic archaeon isolated from a deep-sea hydrothermal vent. It is anaerobic, round to slightly irregular coccus-shaped, 1.2–2.5 μm in diameter, and motile by means of a tuft of flagella.

Thermococcus barophilus is a piezophilic and hyperthermophilic archaeon isolated from a deep-sea hydrothermal vent. It is anaerobic and sulfur-metabolising, with type strain MPT.

Thermococcus peptonophilus is a fast-growing hyperthermophilic archaeon. It is coccus-shaped, obligately anaerobic and about 0.7–2 μm in diameter. It is a strict anaerobe and grows exclusively on complex substrates, such as peptone, casein, tryptone, and yeast extract. It cannot use carbon dioxide as a source of carbon. Although it can grow somewhat in the absence of elemental sulfur, it prefers sulfur.

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.

References

  1. Jolivet, E; L'Haridon, S; Corre, E; Forterre, P; Prieur, D (2003). "Thermococcus gammatolerans sp. nov., a hyperthermophilic archaeon from a deep-sea hydrothermal vent that resists ionizing radiation". Int. J. Syst. Evol. Microbiol. 53 (Pt 3): 847–51. doi: 10.1099/ijs.0.02503-0 . PMID   12807211.
  2. Classification of phyla entry in LPSN ; Euzéby, J.P. (1997). "List of Bacterial Names with Standing in Nomenclature: a folder available on the Internet". International Journal of Systematic and Evolutionary Microbiology. 47 (2): 590–2. doi: 10.1099/00207713-47-2-590 . PMID   9103655.
  3. Tapias, Angels; Leplat, Christophe; Confalonieri, Fabrice (March 2009). "Recovery of ionizing-radiation damage after high doses of gamma ray in the hyperthermophilic archaeon Thermococcus gammatolerans". Extremophiles. 13 (2): 333–343. doi:10.1007/s00792-008-0221-3. PMID   19137239. S2CID   5671089.
  4. θέρμη . Liddell, Henry George ; Scott, Robert ; A Greek–English Lexicon at the Perseus Project
  5. κόκκος . Liddell, Henry George ; Scott, Robert ; A Greek–English Lexicon at the Perseus Project
  6. 1 2 Thermococcus entry in LPSN ; Euzéby, J.P. (1997). "List of Bacterial Names with Standing in Nomenclature: a folder available on the Internet". International Journal of Systematic and Evolutionary Microbiology. 47 (2): 590–2. doi: 10.1099/00207713-47-2-590 . PMID   9103655.
  7. γάμμα . Liddell, Henry George ; Scott, Robert ; A Greek–English Lexicon at the Perseus Project

Further reading