There, protected from space by the ice and invigorated by the energy of the hot vents, microbes adapted and evolved in an intricate dance with extremes of heat and cold. A few microbial species find temperatures less than 194 degrees Fahrenheit too cold to reproduce. At the other extreme, bacteria living in the sea ice around Antarctica find it too hot to breed if the temperature gets much above 53 degrees. Bacteria discovered in the gravel under alpine glaciers in Switzerland live quite comfortably at the freezing point of water. In the interior of Antarctica, with winds so violent and ice so thick that no root can hold, life ekes out a surprisingly rich existence.
Some microbes find refuge from the cold between the grains of porous stone.
Others live and die in the minute gaps between snow crystals at the South Pole, biologist Ed Carpenter at San Francisco State University and USC environmental biologist Douglas Capone discovered. The ambient temperature in the snow where they were found hovered just above 1 degree Fahrenheit. Their habitat was continually bathed in high levels of sterilizing ultraviolet radiation common in the polar region. To survive in such conditions, these seemingly simple creatures each inherit four copies of their genome and an elaborate DNA repair mechanism that compensates for the destructive genetic effects of radiation and desiccation. Researchers believe that is a sign that the ice is composed not of ancient compacted snow but of frozen water from the lake itself.