Psychrophilia

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Psychrophilia (from ancient Greek ψυχρός psychrós “cold”, “cool” and φίλος phílos “loving”) is the property of living beings to prefer low temperatures . Living beings with this property are called psychrophilic (cold-loving). Psychrophilic microorganisms are extremophiles . They usually thrive at −5 to +20 ° C. Cryophiles , which have specialized in temperatures below −10 ° C, represent an increase in psychrophiles .

Overview of the temperature requirements for bacteria

Psychrophilic bacteria have a growth optimum at 15 ° C, but can also live at temperatures below freezing point. Psychrotolerant microorganisms, on the other hand, tolerate low temperatures, but can no longer grow below 3–5 ° C. They play an important role in many biotechnological fermentation processes (see below). The table shows the approximate, overlapping temperature ranges that can be divided into different classes:

Real psychrophilic organisms (also called stenopsychrophilic) cannot tolerate higher temperatures for growth, while psychrotolerant organisms (also called eurypsychrophilic) prefer low temperatures, but can also withstand temperatures up to the mesophilic range.

group Temperatures [° C]
minimum optimum maximum
Psychrophilic (stenopsychrophilic) -5 to +5 12 to 15 15 to 20
Psychrotolerant (eurypsychrophil) 3 to 5 20 to 30 30 to 35
Mesophile 7 to 15 30 to 40 35 to 47
Thermophilic 40 to 45 55 to 75 60 to 90
Hyperthermophile 70 to 80 80 to 90 90 to 110

Occurrence

" Blood snow " in the fjäll mountains of northern Sweden

Psychrophilic microorganisms are often found in alpine and polar regions such as the Alps, the Arctic ( Greenland ) or Antarctica , where they live trapped in the ice in tiny liquid films that are hardly larger than themselves. Other representatives also live in deep, cold water layers of oceans and are therefore barophile at the same time . The cold-loving microorganisms often include bacteria ( Flavobacterium species, Micrococcus antarcticus , Photobacterium profundum , Shewanella benthica , Gallionella ) and archaea ( Methanogenium frigidum , Methanococcoides burtonii , Halorubrum lacusprofundi ), but also fungi and microalgae. The latter include the snow algae that are known for snow and glacier surfaces green or red to color in summer ( Blood Snow ).

Example: Chryseobacterium greenlandense

An example of simultaneously psychrophilic and barophilic bacteria was in the ice from Greenland discovered. The organism, which is less than 0.2 µm in size, is able to survive long periods of time in habitats with low temperatures, high pressure and low oxygen and nutrient content. It survived for more than 120,000 years at a depth of around 3,000 meters.

The bacterium was discovered at Pennsylvania State University and first introduced to the public by Jennifer Loveland-Curtze and colleagues at the American Society for Microbiology's annual meeting on June 3, 2008. They assign it to the Flavobacteriaceae family in the Bacteroidetes strain . The scientific name is Chryseobacterium greenlandense .

Adaptation

Most of the time, the enzymes of psychrophilic microorganisms are specially adapted to these living conditions, similar to the thermophilic microorganisms. Compared to the psychrotolerant organisms that survive at low temperatures - with slowed growth - psychrophilic organisms can also multiply under these conditions.

The cell membrane of these organisms contains a high proportion of polyunsaturated fatty acids with a shortened chain length and increasing branching. This is to ensure that the membrane is sufficiently fluid at low temperatures and does not solidify. In addition, the enzymes are sufficiently flexible and thermally labile at low temperatures. After all, the cytoplasm of those psychrophiles must remain fluid and prevent the formation of ice crystals. In the case of algae, one such “ antifreeze ” is glycerine .

Biotechnological importance

Psychrophilic or psychrotolerant microorganisms (e.g. Brochothrix thermosphacta , Pseudomonas fragi ) can pose a problem when storing refrigerated foods. Despite the low temperatures, these can make a decisive contribution to spoiling. Yersinia enterocolitica , Listeria monocytogenes , Clostridium botulinum and Bacillus cereus are also pathogenic to humans .

On the other hand, beer and many dairy products ( cheese , yogurt ) are made with the help of psychrotolerant microorganisms. These therefore play an important role in biotechnological fermentation.

See also

literature

  • Wolfgang Fritsche: Microbiology . Spektrum Akademischer Verlag, 3rd edition 2001, ISBN 3-8274-1107-6 , pp. 362f.
  • Katharina Munk (Ed.): Pocket textbook Biology: Microbiology , Thieme Verlag, Stuttgart 2008, ISBN 978-3-13-144861-3 , pp. 452ff.
  • Bartlett, DH. (1999): Microbial adaptations to the psychrosphere / piezosphere . In: J Mol Microbiol Biotechnol . 1 (1); 93-100; PMID 10941790 ; PDF (free full text access)
  • Cavicchioli, R. (2006): Cold-adapted archaea. In: Nature reviews. Microbiology. 4 (5); 331-343; PMID 16715049 ; doi : 10.1038 / nrmicro1390

Individual evidence

  1. ^ Wilhelm Gemoll : Greek-German school and hand dictionary. Munich / Vienna 1965.
  2. ↑ Johannes Krämer: Food microbiology , 5th edition, Eugen Ulmer Verlag Stuttgart, 2007, ISBN 978-3-8252-1421-0 ; P. 143.
  3. ↑ Katharina Munk (ed.): Pocket textbook Biology: Microbiology , Thieme Verlag, Stuttgart 2008, ISBN 978-3-13-144861-3 , pp. 452ff.
  4. ↑ Wolfgang Fritsche: Microbiology . Spektrum Akademischer Verlag, 3rd edition 2001, ISBN 3-8274-1107-6 , p. 364.
  5. ^ R. Cavicchioli: Cold-adapted archaea. In: Nature reviews. Microbiology. Volume 4, Number 5, May 2006, pp. 331-343, doi : 10.1038 / nrmicro1390 , PMID 16715049 (review).
  6. ↑ MM Zakaria, M. Ashiuchi, S. Yamamoto, T. Yagi: Optimization for beta-mannanase production of a psychrophilic bacterium, Flavobacterium sp. In: Bioscience, Biotechnology, and Biochemistry . Volume 62, Number 4, April 1998, pp. 655-660, doi : 10.1271 / bbb.62.655 , PMID 9614696 .
  7. ↑ H. Liu, Y. Xu, Y. Ma, P. Zhou: Characterization of Micrococcus antarcticus sp. nov., a psychrophilic bacterium from Antarctica. In: International journal of systematic and evolutionary microbiology. Volume 50, Number 2, March 2000, pp. 715-719, ISSN  1466-5026 . PMID 10758880 .
  8. ↑ Vezzi, A. et al . (2005): Life at depth: Photobacterium profundum genome sequence and expression analysis . In: Science 307 (5714); 1459-1461; PMID 15746425 ; doi: 10.1126 / science.1103341
  9. ↑ Kato, C. and Bartlett, DH. (1997): The molecular biology of barophilic bacteria . In: Extremophiles 1 (3); 111-116; PMID 9680316 ; doi: 10.1007 / s007920050023
  10. ^ PD Franzmann, Y. Liu, DL Balkwill, HC Aldrich, E. Conway de Macario, DR Boone: Methanogenium frigidum sp. nov., a psychrophilic, H2-using methanogen from Ace Lake, Antarctica. In: International journal of systematic bacteriology. Volume 47, Number 4, October 1997, pp. 1068-1072, doi : 10.1099 / 00207713-47-4-1068 , PMID 9336907 .
  11. ^ PD Franzmann, N. Springer, W. Ludwig, E. Conway De Macario, M. Rohde: A Methanogenic Archaeon from Ace Lake, Antarctica: Methanococcoides burtonii sp. nov .. In: Systematic and Applied Microbiology. 15, 1992, pp. 573-581, doi : 10.1016 / S0723-2020 (11) 80117-7 .
  12. ↑ Terry J. McGenity, William D. Grant: Transfer of Halobacterium saccharovorum, Halobacterium sodomense, Halobacterium trapanicum NRC 34021 and Halobacterium lacusprofundi to the Genus Halorubrum gen. Nov., As Halorubrum saccharovorum comb. nov., Halorubrum sodomense comb. nov., Halorubrum trapanicum comb. nov., and Halorubrum lacusprofundi comb. nov .. In: Systematic and Applied Microbiology. 18, 1995, pp. 237-243, doi : 10.1016 / S0723-2020 (11) 80394-2 .
  13. ^ A b A Survivor in Greenland: A Novel Bacterial Species is Found Trapped in 120,000-Year-Old Ice. In: website phys.org . June 3, 2008, accessed November 10, 2019 .
  14. ↑ Jennifer Loveland-Curtze, Vanya Miteva, Jean Brenchley: Novel ultramicrobacterial isolates from a deep Greenland ice core represent a proposed new species, Chryseobacterium greenlandense sp. nov. In: Extremophiles. 14, 2010, pp. 61-69, doi : 10.1007 / s00792-009-0287-6 .
  15. ↑ Georg Fuchs (Ed.), Hans. G. Schlegel (Author): General Microbiology . Thieme Verlag Stuttgart; 8th edition 2007; ISBN 3-13-444608-1 ; P. 561.