Psychrophile

Psychrophiles or cryophiles (adj. cryophilic) are extremophilic organisms that are capable of growth and reproduction in cold temperatures, ranging from −15°C to +10°C. Temperatures as low as −15°C are found in pockets of very salty water (brine) surrounded by sea ice. They can be contrasted with thermophiles, which thrive at unusually hot temperatures. The environments they inhabit are ubiquitous on Earth, as a large fraction of our planetary surface experiences temperatures lower than 15°C. They are present in alpine and arctic soils, high-latitude and deep ocean waters, polar ice, glaciers, and snowfields. They are of particular interest to astrobiology, the field dedicated to the formulation of theory about the possibility of extraterrestrial life, and to geomicrobiology, the study of microbes active in geochemical processes. In experimental work at University of Alaska Fairbanks, a 1000 litre biogas digester using psychrophiles harvested from "mud from a frozen lake in Alaska" has produced 200–300 litres of methane per day, about 20–30 % of the output from digesters in warmer climates.[1]

Psychrophiles use a wide variety of metabolic pathways, including photosynthesis, chemoautotrophy (also sometimes known as lithotrophy), and heterotrophy, and form robust, diverse communities. Most psychrophiles are bacteria or archaea, and psychrophily is present in widely diverse microbial lineages within those broad groups. Additionally, recent research has discovered novel groups of psychrophilic fungi living in oxygen-poor areas under alpine snowfields. A further group of eukaryotic cold-adapted organisms are snow algae, which can cause watermelon snow. Psychrophiles are characterized by lipid cell membranes chemically resistant to the stiffening caused by extreme cold, and often create protein 'antifreezes' to keep their internal space liquid and protect their DNA even in temperatures below water's freezing point.

Examples are Arthrobacter sp., Psychrobacter sp. and members of the genera Halomonas, Pseudomonas, Hyphomonas and Sphingomonas.

See also

References

  1. ^ Gupta, Sujata (2010-11-06). "Biogas comes in from the cold". New Scientist (London: Sunita Harrington): pp. 14. http://www.newscientist.com/article/mg20827854.000-cold-climates-no-bar-to-biogas-production.html. Retrieved 2011-02-04. 

1. Yoshinori Murata, et al., "Genome-wide expression analysis of yeast response during exposure to 4C," Extremophiles (2006) 10:117–12

2. Jill A. Mikucki, et al., "A Contemporary Microbially Maintained Subglacial Ferrous 'Ocean' " Science 324, 397 (2009);



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  • psychrophile — [ psikrɔfil ] adj. et n. m. • 1963; du gr. psukhros « froid » et phile ♦ Biol. Qui vit et se reproduit dans des conditions optimales, à des températures inférieures à 20 oC (en parlant d un micro organisme). N. m. Les psychrophiles. psychrophile… …   Encyclopédie Universelle

  • Psychrophile — Un psychrophile ou psychrotolérant (du grec psukhros, froid) ou cryophile est un type d organisme adapté et capable de survivre à des températures froides par exemple dans les mers polaires ou les abysses (90 % du volume des océans est en… …   Wikipédia en Français

  • Psychrophile — psichrofilai statusas T sritis ekologija ir aplinkotyra apibrėžtis Organizmai, kurių gyvenamosios aplinkos (terpės) temperatūra palyginti žema (0–+30 °C). Tai dažniausiai mikroorganizmai, augantys –6–+5 °C temperatūroje. Kitaip nei mezofilai,… …   Ekologijos terminų aiškinamasis žodynas

  • psychrophile — (si kro faīl) A microorganism that grows well at 0°C and has an optimum growth temperature of 15°C or lower and a temperature maximum around 20°C …   Dictionary of microbiology

  • psychrophile — Organism that grows best at low temperatures …   Dictionary of molecular biology

  • psychrophile — See psychrophilic. * * * …   Universalium

  • psychrophile — noun An organism that can live and thrive at temperatures much lower than normal; a form of extremophile …   Wiktionary

  • psychrophile — psy·chro·phile sī krō .fīl n a psychrophilic organism compare MESOPHILE, THERMOPHILE * * * psy·chro·phile (siґkro fīl) an organism that grows best at low temperatures …   Medical dictionary

  • psychrophile — [ sʌɪkrə(ʊ)fʌɪl] noun Biology an organism that grows best at temperatures close to freezing. Derivatives psychrophilic adjective Origin 1920s: from Gk psukhros cold + phile …   English new terms dictionary

  • psychrophile — psy·chro·phile …   English syllables

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