ИСТИНА

It was assumed that the putative biosphere of Mars could be cryopreserved and had been stored for billions of years in anabiotic state like microbial communities of Arctic and Antarctic permafrost deposits have been preserved till now for millions of years. In this case the main factor causing cell’s death should be ionizing radiation. We irradiated Arctic permafrost microbial community by 1 MGy dose of gamma radiation in simulated Martian conditions (pressure 1 torr, temperature -50°C) to assess duration of survival of potential microorganisms in Martian regolith in anabiotic state. Results of culturing, epifluorescence microscopy, multisubstrate testing, GC-MS of lipids, molecular cloning and Illumina sequencing of 16S rRNA genes of control and irradiated samples will be presented. In general it was found that microbial biomarkers and living cells could be reliably detected in irradiated soil samples. Resistance to 1 MGy dose of irradiation in simulated conditions proves that if there was an Earth-like biosphere on the early Mars microorganisms could survive in the surface or subsurface layers of the Martian regolith for more than tens of millions of years after climate change. The obtained data point out that the radioresistance of microorganisms being entrapped into the complex natural substrates is significantly underestimated. This work was supported by the Russian Foundation for Basic Research (grant № 13-04-01982) and by Russian Science Foundation (grant № 14-50-00029).