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Book Sections Year : 1999

Microbial life in permanently cold soils



he earth contains many low-temperature environments. Over 80% of the earth’s biosphere is permanently cold: 90% of the volume of oceans — which occupy 71% of the earth’s surface — is colder than 5°C. Various aquatic and terrestrial continental environments are also cold, such as polar regions (14% of the earth surface), high mountains, and deep lakes.1 These continental environments are characterized by stable or unstable temperatures. Many organisms are able to develop in cold habitats, but cold adaptation can be a tolerance or a preference. These microorganisms are called psychrophiles or psychrotrophs (more exactly psychrotolerants) depending on their maximum growth: psychrophiles do not grow at 20°C and above, psychrotrophs grow better at temperatures above 20°C.2 Consequently, psychrophilic microorganisms, being heat-sensitive, can live only in permanently cold habitats, while psychrotrophic microorganisms are found in both permanently or temporarily cold habitats. Most continental habitats encounter large variations of temperature. Even temperate soils contain high numbers of psychrotolerant microorganisms which can be isolated after incubation at a temperature below 5°C but they grow faster in spring and summer, while psychrophiles are excluded. However, some continental habitats are permanently cold and can be favorable to true psychrophiles.

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hal-02570942 , version 1 (12-05-2020)



Anne-Monique Gounot. Microbial life in permanently cold soils. Cold-Adapted Organisms : Ecology, Physiology, Enzymology and Molecular Biology, Springer Berlin Heidelberg, pp.3-15, 1999, 978-3-642-08445-4. ⟨10.1007/978-3-662-06285-2_1⟩. ⟨hal-02570942⟩
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