Psychrophiles and Psychrotrophs

Psychrophiles are extremophilic bacteria or archaea which are cold-loving having an optimal temperature for growth at about 15°C or lower, a maximal temperature for growth at about 20°C and a minimal temperature for growth at 0°C or lower. Psychrotrophs are cold-tolerant bacteria or archaea that have the ability to grow at low temperatures but have optimal and maximal growth temperatures above 15 and 20°C, respectively. The Earth has extensive cold ecosystems that do not reach temperatures greater than 5°C (e.g., polar surface and ice-cap regions, permafrost and worldwide deep oceans). Psychrophiles and psychrotrophs are cold-loving extremophiles adroitly adapted to these environmental conditions, and are often capable of enduring extended periods of cryobiosis.