Psychrophilic microorganisms as important source for biotechnological processes

Abstract

The major parts of Earth’s environments are cold and have temperatures below 5°C (Gounot 1999; Russell and Cowan 2005). About 70% of the freshwater is ice and about 14% from the Earth’s biosphere is represented by terrestrial and aquatic polar areas (Priscu and Christner 2004). The depth of the oceans, the poles, and high mountains are the most important cold regions on Earth (Russell and Cowan 2005). Global ice, for example, covers 6.5 million km² which increases to 14.4 million km² in wintertime (Perovich et al. 2002). Here we can meet representatives from all domains of the living world. Two categories of microorganisms were discovered in such cold environments. First, the psychrophiles with an optimum growth temperature of about 15°C or even less, which cannot grow above 20°C (Moyer and Morita 2007); second, the psychrotolerants with an optimum growth temperature of 20–30°C, which are able to grow and exhibit activity at temperatures close to the freezing point of water (Madigan and Jung 2003). The lowest temperature for life’s activities is −20°C under certain defined conditions (Rivkina et al. 2000; Gilichinsky 2002; D’Amico et al. 2006); others consider the temperature limits for reproduction as −12°C and for metabolism as −20°C (Bakermans 2008). Colwellia psychrerythraea strain 34H is motile at −10°C, as observed by transmitted light microscopy (Junge et al. 2003). Psychrophilic microorganisms are dominant in permanently cold environments such as Antarctic waters and have important roles in the biogeochemical cycles in the polar zones (Helmke and Weyland 2004).