The freezing and thawing processes occurring at various spatio-temporal scales in soils can lead to cyclical changes in their temperature and moisture fields. The changes result in alterations of physical and chemical properties in microbial habitats, as well as direct or indirect injuries to the cell membranes and organelles. These injuries are caused by ice crystalization disrupting the cellular walls and changes in the osmotic balances. Due to restriction of the environments in seasonally frozen soils and in permafrost, cell becomes dormant, and DNA, protein synthesis and energy supply are maintained only at extremely low levels needed for cell survival. The biogeochemical cycles of carbon and nitrogen, mediated and modulated by microbial activity, are influenced by the freeze-thaw process in the seasonally-frozen ground and the active layer of permafrost. The permafrost environments tend to conserve biological objects and diversity at temperatures below 0℃ and serve as physical and chemical barriers which sharply restrict the influences of external factors, including background radiation, on the microorganisms. During the long process of adaptation, microbes correspondingly developed tolerant mechanisms and structures and functions at both cellular and molecular levels consistent with the permafrost environments. This provides important implications in the search for past or extant life in the presumed permafrost on Mars, which apparently had a water environment earlier in its history, or perhaps in the near-surface of some moons with a methane environment.