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Microorganisms with an optimum growth temperature of ≤15°C that do not grow above 20°C are termed psychrophiles. Psychrotolerant microorganisms have an optimum temperature between 20°C and 40°C, but are also capable of growth at 0°C. Psychrophiles grow in permanently cold environments (e.g. areas of the Arctic/Antarctic and the ocean depths), whereas psychrotolerant microorganisms are more often isolated from boreal environments (high altitudes and extreme latitudes) where temperatures fluctuate widely over the year. Psychrophilic and psychrotolerant microorganisms express enzymes with an increased activity at low temperatures and with a lower maximum temperature, although maximum rates are usually lower than their mesophilic counterparts at 37°C [1]. Cold adapted enzymes have a greater flexibility that allows them to undergo conformational changes at low temperatures during catalytic events. The disadvantage of this flexibility is a low stability of the enzyme structure at higher temperatures [1].

See also


[1] Feller (2003) Cell Mol Life Sci 60, 648-662.

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