Psychrophiles: Life in the Cold
from: Extremophiles: Microbiology and Biotechnology (Edited by: Roberto Paul Anitori). Caister Academic Press, U.K. (2012)
Psychrophilic, or cold-loving, organisms actively live at low temperatures. Psychrophily is not an uncommon trait; cold-adapted organisms are found throughout the three domains of life and successfully inhabit a wide variety of low temperature environments. The ongoing investigation of these environments continues to broaden our view of what is possible for life on Earth. Cold-adapted microorganisms have evolved mechanisms to deal with the thermodynamic constraints of low temperatures. To combat the stability and decreased flexibility of macromolecules, psychrophiles generally increase the disorder within macromolecules to maintain fluidity or flexibility and hence function at low temperatures. To contend with reduced water activity and the presence of ice crystals, cryoprotectants are produced. To counteract decreased reaction and diffusion rates, psychrophiles practice efficient growth. Currently, the functional low-temperature limits of psychrophiles are minus 12 degrees celsius for reproduction and minus 20 degrees celsius for metabolism. The availability of liquid water appears to be the major growth-limiting factor at subzero temperatures. Examination of molecular and physiological adaptations to low temperatures is increasing our comprehension and appreciation of the capabilities of psychrophiles and their contribution to nutrient cycling in low temperature environments read more ...