Survival of microorganisms during two-year exposure in outer space near the ISS

The results of the "Test" experiment on the study of the survival and variability of microorganisms in open space near the International Space Station are presented. It was found that after two years of exposure, spore-forming bacteria of the species Bacillus subtilis , fungi of the species Aurobasidium pullulans and archaea of the species Methanosarcina mazei S-6T, deposited on cotton wool, are able to survive, and their numbers decreased equally, regardless of whether the microorganisms belong to different taxonomic groups. Such duration of microorganism survival may be the result of their dehydration and partial lyophilization in the vacuum of near-Earth space. A study of the radiation resistance of the fungus species Aurobasidium pullulans after two-year stay in space revealed that resistance to gamma radiation increased in 30% of subcultures compared to the original culture. It was found that the response to the action of different concentrations of hydrogen peroxide and 1% chlorine in the control strain Aurobasidium pullulans VKM F-1116 is more pronounced than in the studied surviving strains on the ISS of a similar species.