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Thermophile

from ancient Greek θερμός (thermós) - warm, φίλος (phílos) - loving
Deutsch: Thermophil, Thermophile

1 Definition

Organisms prefering high temperatures between 45 and 80°C are called thermophiles. They thus belong to the group of extremophiles. The adjective is thermophilic.

2 Incidence

Thermophiles belong to the kingdom of prokaryotes and can be found in the domain Eubacteria, but above all in the Archaea. They live in hot regions such as hot springs and the black and white smokers of the deep sea.

3 Classification

Thermophiles can be classified according to their optimal growth temperatures:

  • moderate thermophiles: 50-64 °C
  • extreme thermophiles 65-79 °C
  • hyperthermophiles: 80 °C

Another system classifies thermophiles according to the temperatures at which growth is possible:

  • Facultative thermophiles (also moderate thermophiles) can live at both high and low temperatures (< 50 °C) while
  • obligatory thermophiles (also extreme thermophiles) depend on high temperatures for growth.
  • Hyperthermophiles can only grow at temperatures of at least 80 °C.

The metabolism of many hyperthermophiles also depends on other "unusual" factors, so that some of them can also be attributed to other groups of extremophiles. Thus, many Archaea need elementary sulfur for growth. While some are also attributed to the anaerobes using sulfur instead of oxygen as electron acceptor in cell respiration, others belong to the lithotrophes who oxidize sulfur to sulfuric acid as an energy source. The latter requires the adaptation of this Archaea to low pH-values, so an assignment to the azidophiles is also possible.
Those prokaryotes are therefore found in hot, sulphurous habitats, which are usually located near volcanoes such as hot springs, geysers and fumaroles.

4 Importance

Thermophilic bacteria and archaea, for example, play a major role in composting and the process of biogas (methane) production, which can be operated under thermophilic conditions. Due to the higher temperatures, the substrate turnover is, according to the laws of thermodynamics, increased compared to mesophilic conditions.
Some enzymes from extremophilic organisms are of importance in biotechnology, they are called extremozymes. Examples are lipases, amylases and proteases in detergents that can operate at very high washing temperatures and the Taq-polymerase which, due to its optimum temperature, is used in DNA amplification by polymerase chain reaction (PCR).

Specialties: Biology

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