@Dudeski Particularly challenging temperate environments are found in the soil surface on the continental sides of large mountain chains located near the oceans. These regions frequently experience Foehn winds, also known as Chinook or Mistral winds, which develop when air descends from high elevations and heats due to compression. Chinook winds in North America can raise winter temperatures by 20°C in less than 1 h and frequently melt the snow cover. These conditions present additional challenges to microbial species that may endure summer temperatures as high as 35°C and winter temperatures that can dip to −35°C, as well as alternating freezing and thawing periods during the cold season. At these temperatures, microorganisms can be injured or killed as a result of cold shock, freezing, prolonged exposure to subzero temperatures, and subsequent warming (
17), and injury or death is often due to damage to membranes or cell walls that results in permeability changes, as well as to damage to DNA (
18). Indeed, the susceptibility of most enteric bacteria to freezing has allowed disposal of wastewater from polar research stations in a “sewage bulb” in the snowpack above glacial ice (
28). In addition, commercial interests argue that the use of secondary wastewater for snowmaking leads to killing or irreversible damage of bacteria so that in the spring, runoff water is effectively “disinfected” (
25). Given these challenges, the fact that soil consortia thrive in Chinook regions is a testimony either to environmental heterogeneity or to the remarkable adaptive abilities of microbial communities.
