Extremophilia

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As extremophilic are organisms referred to, which have adapted to extreme environmental conditions, which are generally considered hostile. These are mostly single-cell microorganisms . Non-extremophilic organisms are called mesophiles .

Systematics

The term extremophile was coined in 1974 by RD MacElroy. Many extremophiles are members of the domain of the archaea and in fact the two terms are occasionally used interchangeably , although there are many mesophilic archaea, there are also numerous extremophilic bacteria and even eukaryotes . Although by far the largest proportion of extremophiles can be found among the unicellular organisms , there are also examples of multicellular organisms ( Metazoa ) among these specialists. Examples of extremophilic multicellular cells are the psychrophilic Grylloblattodea ( insects ) and the Antarctic krill ( Crustacea ).

Enzymes that originate from extremophilic organisms and were produced recombinantly are of great importance in biotechnology . For example, the thermostable DNA polymerase used in the polymerase chain reaction (PCR) originally comes from the thermophilic bacterium Thermus aquaticus or the archaea Pyrococcus furiosus .

Even viruses were discovered in extreme habitats such. B. Sulfolobus turreted icosahedral virus .

Categories of extremophiles

There are many different categories of extremophiles. The classification corresponds to the way in which the environmental conditions of the respective organism differ from what is considered "normal" from a human point of view. This classification is not exclusive, which means that some extremophiles have several categories. Organisms that live, for example, inside hot rocks far below the surface of the earth are not only endolites , but also thermophilic and barophilic .

The following categories are known:

  • Thermophiles : Organisms that are optimally adapted to high temperatures (80 ° C and more)
  • Psychrophiles : organisms that are optimally adapted to low temperatures (15 ° C and lower)
  • Cryophiles : Organisms that are adapted to particularly cold environments below −10 ° C. They represent the increase in psychrophilia.
  • Halophiles : Organisms that are optimally adapted to high salt concentrations (at least 0.2  mol / l salt)
  • Methanophiles : Organisms that are adapted to high methane concentrations, for example bacteria in methane hydrate and Hesiocaeca methanicola (not to be confused with methane producers , which, however, endure a certain concentration of their metabolic product).
  • Alkali philes : organisms that are optimally adapted to a high pH value (pH 9 and higher)
  • Acidophiles : Organisms that are optimally adapted to a low pH value (pH 3 and lower)
  • Barophilic : organisms that optimally at high hydrostatic pressure adapted
  • Radiophiles : Organisms that tolerate very high doses of ionizing radiation (see Deinococcus radiodurans ), or are even able to convert melanin into energy with the help of the pigment ( radiosynthesis ) and use this for their growth. These are certain melanin-rich types of fungus that were noticeable as a black coating on the reactor walls in the destroyed Chernobyl nuclear reactor.
  • Endolites : Organisms that live inside rocks
  • Oligotrophs : Organisms that are optimally adapted to a nutrient-poor environment
  • Toxitolerante : Organisms that can withstand large concentrations of destructive agents such as toxins or radiation . Some can even survive in benzene- saturated water, while others thrive in the cooling water tank of a nuclear reactor
  • Xerotolerants : Organisms that are adapted to an environment with little water. Examples are extremely halophilic or endolithic organisms.

Extremophiles who occur under several extreme environmental conditions are known as polyextremophiles. Examples of polyextremophilia are Deinococcus radiodurans and tardigrade .

Since extremophilic organisms can sometimes also exist under space conditions, they are of interest for astrobiological research projects, for example on the probability of panspermia .

See also

literature

  • Kazem Kashefi, Derek R. Lovley: Extending the Upper Temperature Limit for Life . In: Science . tape 301 , 2003, p. 934 , doi : 10.1126 / science.1086823 , PMID 12920290 .
  • Walter Kleesattel: Survival in ice, desert and deep sea . Scientific Book Society, Darmstadt 1999, ISBN 3-534-14090-7 .
  • Klaus Hausmann: Extremophiles - Microorganisms in unusual habitats. VCH-Verlag, Weinheim 1995, ISBN 3-527-30068-6 .
  • Garabed Antranikian: Biotechnology of extremophiles. Springer, Berlin 1998, ISBN 3-540-63817-2 .
  • K. Horikoshi: Extremophiles in deep-sea environments. Springer, Tokyo 1999, ISBN 4-431-70263-6 .
  • Charles Gerday and Nicolas Glansdorff: Physiology and biochemistry of extremophiles. ASM Press, Washington, DC 2007, ISBN 978-1-55581-422-9 .
  • Birgit Sattler, Hans Puxbaum and Roland Psenner: Bacteria in the air - Gone with the wind . In: Biology in Our Time . Vol. 32, No. 1, 2002, pp. 42-49, ISSN  0045-205X .
  • Michael Groß: The eccentric of life - cells between heat shock and cold stress . Spektrum Akademischer Verlag, Heidelberg, Berlin, Oxford 1997, ISBN 3-8274-0139-9 .
  • Iain Gilmour et al: Examples of extremophilic microorganism (polyextremophiles), Table 2 . In: An introduction to astrobiology. Cambridge Univ. Press, Cambridge 2004, ISBN 0-521-83736-7 , pp. 74-80.
  • Mosè Rossi u. a .: Extremophiles 2002 . In: Journal of Bacteriology . tape 185 , no. 13 , 2003, p. 3683-3689 , doi : 10.1128 / JB.185.13.3683-3689.2003 , PMID 12813059 , PMC 161588 (free full text).
  • Helga Stan-Lotter, Sergiu Fendrihan (Ed.): Adaption of Microbial Life to Environmental Extremes . Springer, Vienna [a. a.] 2012, ISBN 978-3-211-99690-4 , doi : 10.1007 / 978-3-211-99691-1 .

Web links

Individual evidence

  1. "RDMacElroy first coined the term" extremophiles "in a 1974 paper entitled" Some comments on the evolution of extremophiles ", but definitions of extreme and extremophiles are of course anthropocentric." In: Joseph Seckbach et al .: Polyextremophiles - life under multiple forms of stress. Springer, Dordrecht 2013, ISBN 978-94-007-6487-3 .
  2. ^ Helga Stan-Lotter: Physico-chemical boundaries of life. In: Helga Stan-Lotter et al .: Adaption of microbial life to environmental extremes - novel research results and application. Springer, Vienna 2012, ISBN 978-3-211-99690-4 , p. 10ff.
  3. ^ Marc Le Romancer et al .: Viruses in extreme environments. Reviews in environmental science and bio-technology 6, 1-3 (2007), pp. 17-31, abstract @ univ-brest.fr, accessed on August 3, 2012
  4. Fungus eats radioactivity. In: Wissenschaft.de. May 23, 2007, accessed September 8, 2019 .
  5. Lynn J. Rothschild et al.: Life in extreme environments. In: Nature 409, 2001, pp. 1092-1101. doi : 10.1038 / 35059215 , pdf ; Lynn J. Rothschild: A biologist's guide to the Solar System. In: Constance M. Bertka: Exploring the origin, extent, and future of life. Cambridge University Press, Cambridge, 2009, ISBN 978-0-521-86363-6 . P. 132.
  6. ^ Joseph Seckbach et al .: Polyextremophiles - life under multiple forms of stress. Springer, Dordrecht 2013, ISBN 978-94-007-6488-0 .
  7. ^ Ricardo Cavicchioli: Extremophiles and the Search for Extraterrestrial Life. Astrobiology, August 2002, Volume 2, Issue 3, pp. 281-292, doi : 10.1089 / 153110702762027862 .
  8. Comparative Survival Analysis of D. radiodurans, N. magadii, and H. volcanii Exposed to Vacuum Ultraviolet Irradiation spaceref.com, accessed October 5, 2011.
  9. Peter Reuell: Harvard study suggests asteroids might play key role in spreading life. In: Harvard Gazette. July 8, 2019, Retrieved October 6, 2019 (American English).
  10. Ker Than: Bacteria Grow Under 400,000 Times Earth's Gravity. April 26, 2011, accessed October 6, 2019 .