Thermophilia (from ancient Greek θερμός thermós “warm” and φίλος phílos “loving”) is the property of living beings , especially microorganisms , to prefer high temperatures (45–80 ° C). Living things with this property are called thermophilic . If the preferred temperature range is above 80 ° C, then we speak of hyperthermophilic organisms.
Thermophilic organisms are found in particular among the archaea and (less often) among the bacteria . Their proteins are thermally stable and denature more slowly. For some archaea, the optimal living conditions are far above 70 ° C; they mainly live in hot springs and geysers . Some thermophilic bacteria and fungi (e.g. Chaetomium thermophilum ) prefer to colonize compost heaps , inside of which the temperature has risen to over 45 ° C due to rotting processes.
In the deep sea, in areas with volcanic activity - especially on mid-ocean ridges - there are ecosystems in which the water temperatures even exceed 100 ° C due to heating by rising magma and the high hydrostatic pressure, but which nevertheless contain a rich biocenosis . The current front runners among the hyperthermophilic microorganisms are the Archaea Strain 121 , which doubles its population every 24 hours at 121 ° C (discovered in 2003 on a black smoker in the Juan de Fuca ridge ), and the Archaea Methanopyrus kandleri , which also can grow at 122 ° C (discovered in 1991 on a black smoker in the Gulf of California ). This replaces the previous record holder Pyrolobus fumarii , which is able to grow up to a maximum of 113 ° C. The worm Alvinella pompejana also lives in the chimneys of black smokers, tolerating temperatures of up to 80 ° C in its habitat and thus holding the record among thermophilic eukaryotes .
Maximum temperature for living things
It is assumed that the absolute upper limit for life of any kind is around 150 ° C, since at higher temperatures the DNA (the carrier of genetic information) disintegrates through hydrolysis at such a rapid rate that any currently known DNA repair system would be overwhelmed. Tardigrades are able to survive temperatures of up to 151 ° C under certain conditions and with a certain probability and thus provisionally confirm this limit range. Nevertheless, nobody can rule out the existence of so-called ultrathermophilic organisms with absolute certainty . These currently still hypothetical living beings could have developed mechanisms by which they survive at even higher temperatures, such as those found in e.g. B. found in some hot water springs near which colonies of Pyrolobus fumarii exist; temperatures of up to 350 ° C were measured there.
In technical microbiology ( biotechnology ), bacterial processes run under thermophilic conditions when they take place at over 50 ° C. If the temperatures are lower, one speaks of mesophilic conditions (30–40 ° C) or psychrophilic conditions (below 20 ° C). Both fermentation and composting can be carried out under thermophilic conditions.
Many enzymes of thermophilic bacteria are used today in various technical processes, e.g. B. proteases or lipases in detergents . A thermostable DNA polymerase is used in the polymerase chain reaction (PCR).
- Wilhelm Gemoll: Greek-German school and hand dictionary. Munich / Vienna 1965.
- Lovley, D. & Kashefi, K. (2003): Extending the upper temperature limit for life. In: Science . Vol. 301, pp. 934-524. PMID 12920290 PDF ( page no longer available , search in web archives ) Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice. .
- Unboilable bug points to hotter origin of life guardian.co.uk, August 15, 2003; Strain 121 en.wikipedia, accessed December 1, 2010.
- Cowen, DA (2004): The upper temperature of life - where do we draw the line? In: Trends Microbiol. Vol. 12, pp. 58-60. PMID 15040324 .