Cryophilic Bacteria

Cryophilic bacteria, microorganisms that live at low temperatures; another name for them is psychrophilic bacteria. According to Lehmann and Neumann, the optimal temperature for these microorganisms is 15-20°C, with a minimum of 0°C and maximum of 30°C; however, in some cryophilic species, the optimal temperature is considerably lower. Cryophilic bacteria are natural inhabitants of polar countries and northern cold seas. They do not form spores. Many species of aquatic bacteria, some luminous bacteria, and some iron bacteria belong to the cryophilic bacteria. Cold generally has little effect on luminous bacteria; among iron bacteria, the cryophilic one is Spirophyllum ferrugineum, whose optimal temperature is 6°C. Typical psychrophilic bacteria are very sensitive even to moderately high temperatures; they die from prolonged exposure to 40°C, whereas their reproduction ceases at even lower temperatures.