Thermophile
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fr:Thermophile de:Thermophil ja:好熱菌
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A thermophile is an organism – a type of extremophile – which thrives at relatively high temperatures, up to about 60 °C. Many thermophiles are archaea.
Thermophiles have been found in various geothermally heated regions of the Earth such as hot springs like those in Yellowstone National Park (see image) and deep sea hydrothermal vents.
As a prerequisite for their survival, thermophiles contain enzymes that can function at high temperature. Some of these enzymes are used in molecular biology (for example heat-stable DNA polymerases for polymerase chain reaction), and in washing agents.
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Importance of enzymes from thermophiles
The enzymes isolated from some extremophiles have proven to be of great use in the biotechnology industry, able to function under conditions that would denature enzymes taken from most "normal" organisms.
The most commonly used DNA polymerase for the polymerase chain reaction technique is Taq DNA polymerase, originally isolated from Thermus aquaticus, a bacterial species found in surface aquatic locations such as Yellowstone National Park hot springs. For a few PCR applications, the lack of proofreading by Taq DNA polymerase is a problem.
The DNA polymerase from Thermococcus litoralis was shown to have a proofreading exonuclease activity. (Mattila et al, 1991)Thermococcus litoralis was isolated from a deep sea hydrothermal vent. This DNA polymerase is marketed as "Vent" polymerase.
Taq DNA polymerase is adequate for most PCR, but one study (Hamilton et al, 2001). reported that higher fidelity thermostable DNA polymerases such as Vent account for as much as 30% of DNA polymerase sales.
Some thermophilic organisms
- Thermus aquaticus
- Thermus thermophilus
- Chloroflexus aurantiacus (photosynthetic bacterium)
- Thermococcus litoralis (see extremophiles)
- Pyrodictium abyssi (archaea)
The Pompeii worm survives the scalding temperatures surrounding deep-sea hydrothermal vents thanks to a symbiotic relationship with thermophilic bacteria.
See also
Contrast with mesophile and psychrophile
References
- Mattila P, Korpela J, Tenkanen T, Pitkanen K. (1991) "Fidelity of DNA synthesis by the Thermococcus litoralis DNA polymerase--an extremely heat stable enzyme with proofreading activity (http://www.pubmedcentral.nih.gov/pagerender.fcgi?artid=328798&pageindex=7#page)" in Nucleic Acids Res. Sep 25;19(18):4967-73
- Hamilton SC, Farchaus JW, Davis MC (2001) "DNA polymerases as engines for biotechnology" by . in Biotechniques, 31:370-6, 378-80, 382-3
- Zierenberg Robert A., Adams Michael W. W., and Arp Alissa J. (2000) "Life in extreme environments: Hydrothermal vents (http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pubmed&pubmedid=11058150)" in Proc Natl Acad Sci U S A. 2000 November; 97(24): 1296112962.