Moll D M, Vestal J R
Department of Biological Sciences, University of Cincinnati, Ohio 45221-0006, USA.
Icarus. 1992 Aug;98(2):233-9. doi: 10.1016/0019-1035(92)90092-l.
Manned exploration of Mars may result in the contamination of that planet with terrestrial microbes, a situation requiring assessment of the survival potential of possible contaminating organisms. In this study, the survival of Bacillius subtilis, Azotobacter chroococcum, and the enteric bacteriophage MS2 was examined in clays representing terrestrial (Wyoming type montmorillonite) or Martian (Fe(3+)-montmorillonite) soils exposed to terrestrial and Martian environmental conditions of temperature and atmospheric pressure and composition, but not to UV flux or oxidizing conditions. Survival of bacteria was determined by standard plate counts and biochemical and physiological measurements over 112 days. Extractable lipid phosphate was used to measure microbial biomass, and the rate of 14C-acetate incorporation into microbial lipids was used to determine physiological activity. MS2 survival was assayed by plaque counts. Both bacterial types survived terrestrial or Martian conditions in Wyoming montmorillonite better than Martian conditions in Fe(3+)-montmorillonite. Decreased survival may have been caused by the lower pH of the Fe(3+)-montmorillonite compared to Wyoming montmorillonite. MS2 survived simulated Mars conditions better than the terrestrial environment, likely due to stabilization of the virus caused by the cold and dry conditions of the simulated Martian environment. The survival of MS2 in the simulated Martian environment is the first published indication that viruses may be able to survive in Martian type soils. This work may have implications for planetary protection for future Mars missions.
载人火星探索可能会导致地球微生物污染火星，这种情况需要评估可能的污染生物的生存潜力。在本研究中，研究了枯草芽孢杆菌、褐球固氮菌和肠道噬菌体MS2在代表地球（怀俄明型蒙脱石）或火星（Fe(3 +)-蒙脱石）土壤的粘土中的存活情况，这些粘土暴露于地球和火星的温度、大气压力及成分的环境条件下，但未暴露于紫外线通量或氧化条件。通过标准平板计数以及在112天内进行生化和生理测量来确定细菌的存活情况。可提取的脂质磷酸盐用于测量微生物生物量，14C-乙酸掺入微生物脂质的速率用于确定生理活性。通过噬菌斑计数来检测MS2的存活情况。两种细菌在怀俄明蒙脱石中的地球或火星条件下的存活情况都比在Fe(3 +)-蒙脱石中的火星条件下要好。存活率降低可能是由于Fe(3 +)-蒙脱石的pH值低于怀俄明蒙脱石。MS2在模拟火星条件下的存活情况优于陆地环境，这可能是由于模拟火星环境的寒冷和干燥条件使病毒得以稳定。MS2在模拟火星环境中的存活是首次发表的表明病毒可能能够在火星类型土壤中存活的迹象。这项工作可能对未来火星任务的行星保护具有重要意义。
