Extremophile

Organisms are called extremophiles phil, that have adapted to extreme environmental conditions, which are generally considered to be hostile to life. In most cases these are single-celled microorganisms. Non- extremophile organisms is called Mesophilic.

System

The term extremophiles in 1974 by R. D. MacElroy coined. Many extremophiles are members of the domain Archaea, and in fact the two terms are sometimes used interchangeably, although there are many mesophilic archaea, in addition, there are also numerous extremophile bacteria and even eukaryotes. Although the lion's share is to be found in extremophiles in the individual learning, there are also examples of multicellular organisms ( Metazoa ) among these specialists. Examples of extremophile multicellular organisms are the psychrophilic Grylloblattodea ( insects) and Antarctic krill ( Crustacea).

An important role in biotechnology have enzymes derived from extremophile organisms and were produced recombinantly. For example, the derived thermostable DNA polymerase in the polymerase chain reaction (PCR) used originally from the thermophilic bacterium Thermus aquaticus, Pyrococcus furiosus, or Archaee.

Even viruses could be detected in extreme habitats, such as Sulfolobus turreted - Icosahedral virus.

Categories of extremophiles

There are many different categories of extremophile organisms. The classification is according to the way how the environmental conditions of the organism differ from what is seen in human terms, as " normal". This classification is not exclusive, that is, to some extremophiles meet several categories. Organisms that live for example in the interior of hot rocks far below the surface, are not only Endolithe but also thermophilic and barophil.

The following categories are known:

• Thermophilic: organisms that optimally at high temperatures (80 ° C and more) are adapted
• Psychrophiles: organisms that are optimally adapted to low temperatures ( 15 ° C and lower)
• Kryophile: organisms that are adapted to extremely cold environments below -10 ° C. Make the increase of psychrophiles dar.
• Halophilic: organisms optimally to high salt concentrations ( at least 0.2 mol / l of salt ) are adapted
• Methanophile: organisms that are adapted to a high methane concentrations, for example, bacteria in the methane hydrate
• Alkali Phile: organisms that optimally at high pH ( pH 9 and above) are adjusted
• Barophilic: organisms that are optimally adapted to high hydrostatic pressure
• Radio Audiophile: organisms that tolerate very high doses of ionizing radiation (see Deinococcus radiodurans ), or even using the pigment melanin in energy to convert assets and can use for their growth. It is certain melanin- rich fungi that were conspicuous as a black deposit on the reactor walls in the destroyed nuclear reactor at Chernobyl.
• Endolithe: organisms that live inside of rocks
• Oligotrophic: organisms that are best adapted to a nutrient-poor environment
• Toxitolerante: organisms that can withstand the large concentrations of destructive agents such as toxins or radiation. So some can survive even in benzene -saturated water, others thrive in the cooling water tank of a nuclear reactor
• Xerotolerante: organisms that are adapted to a low-water environment. Examples are extremely halophilic or endolithic organisms.

Extremophiles that exist with the more extreme environmental conditions are referred to as Polyextremophile. Examples of Polyextremophilie are Deinococcus radiodurans and tardigrades.

Since extremophile organisms can exist under space conditions in part, they are for astrobiological research projects of interest.