ABSTRACT
The permafrost microbial community has been characterized as a “community of survivors” (Friedmann, 1994) based on the continued viability of many of their members for hundreds to millions of years in the frozen state. Despite the extreme conditions of low temperature, low nutrients, and low water activity associated with this environment, a large diversity of viable microorganisms exists in even the deepest layers of permafrost. This continually frozen soil matrix contain members of the bacteria, archaea, and some green algae and yeast that will grow on appropriate media. Other
eukaryotes have not been cultivated from permafrost layers older than 10,000 years. These microbes may have responses to the stress conditions that prolong their survival under the stable conditions of permafrost. Known response reactions include physiological changes to membrane composition, which maintain fluidity; changes in protein production; a reduction in cell size; and the production of internal osmolytes.
