Earth microbes may contaminate the search for life on Mars

Bacteria common to spacecraft may be able to survive the harsh environs of Mars long enough to inadvertently contaminate Mars with terrestrial life according to research published in the April 2010 issue of the journal Applied and Environmental Microbiology.

The search for life on Mars remains a stated goal of NASA’s Mars Exploration Program and Astrobiology Institutes. To preserve the pristine environments, the bioloads on spacecraft headed to Mars are subject to sterilization designed to prevent the contamination of the Martian surface.

Despite sterilization efforts made to reduce the bioload on spacecraft, recent studies have shown that diverse microbial communities remain at the time of launch. The sterile nature of spacecraft assembly facilities ensures that only the most resilient species survive, including acinetobacter, bacillus, escherichia, staphylococcus and streptococcus.

Researchers from the University of Central Florida replicated Mars-like conditions by inducing desiccation, hypobaria, low temperatures, and UV irradiation. During the week-long study they found that Escherichia coli a potential spacecraft contaminant, may likely survive but not grow on the surface of Mars if it were shielded from UV irradiation by thin layers of dust or UV-protected niches in spacecraft.

“If long-term microbial survival is possible on Mars, then past and future explorations of Mars may provide the microbial inoculum for seeding Mars with terrestrial life,” say the researchers. “Thus, a diversity of microbial species should be studied to characterize their potential for long term survival on Mars.”

###

Applied and Environmental Microbiology is a journal published by the American Society for Microbiology. The American Society for Microbiology, headquartered in Washington, D.C., is the largest single life science association, with 40,000 members worldwide. Its members work in educational, research, industrial, and government settings on issues such as the environment, the prevention and treatment of infectious diseases, laboratory and diagnostic medicine, and food and water safety. The ASM’s mission is to gain a better understanding of basic life processes and to promote the application of this knowledge for improved health and economic and environmental well-being.