A preliminary survey of the cellular responses of the black fungus Cryomyces antarcticus to long and short-term dehydration

The McMurdo Dry Valleys in Southern Victoria Land, Antarctica, are known for their extreme aridity, cold, and nutrient-poor conditions. These valleys provide a valuable comparison to environments on Mars. The survival of microorganisms in these areas hinges on their ability to withstand dehydra-tion due to the limited availability of liquid water. Some microorganisms have adapted to survive extended periods of metabolic inactivity and dehydration, a physiological response to the harsh conditions in which they exist. This adaptation is significant for astrobiology studies as it allows for testing the resilience of microorganisms under extraterrestrial conditions, exploring the boundaries and potential for life beyond Earth. In this study, we examined the survivability, metabolic activity, cellular membrane integrity, and ultrastructural damage of Cryomyces antarcticus, a eukaryotic organism used for astrobiological studies, following two dehydration processes. We conducted a fast dehydration process, simulating what happens on the sur- face of Antarctic rocks under typical environmental conditions, and a slow dehydration process, which is commonly used in astrobiological experiments. Our findings revealed a higher percentage of damaged cells following slow dehydration treatments, confirming that rapid dehydration reflects the adaptability of microorganisms to respond to sudden and drastic changes in the Antarctic environment.