Microbial survival rates in soil under sub-zero, low-pressure and UV conditions

We studied the effects of different environmental stresses on microbial populations. E. coli and D. radiodurans were exposed to sub-zero temperature, low-pressure, and UV radiation conditions. The viability of microbial populations in salt water soil, fresh water soil, and sea water was determined. Laboratory experiments were designed to simulate extreme environments to test whether or not selected microbes can remain viable after 10-day exposure to subzero temperatures, low-pressure conditions and combined subzero temperature and low-pressure conditions. Additional experiments were carried out to test whether or not selected microbes can remain viable after 24 hour exposure to UV radiation, combined UV radiation and low-pressure conditions, and finally, combined UV radiation, subzero temperature and low-pressure conditions. Results demonstrate that microorganisms such as E. coli and the radiation resistant microbe D. radiodurans can remain viable under these exposure conditions to a variable degree. These results have direct implication for assessing viabilities of terrestrial microbes in Martian environments