Effects of atmospheric pressure on the survival of photosynthetic microorganisms during simulations of ecopoesis

摘要

Three cyanobacteria (Anabaena sp., Plectonema boryanum and ChroococcidiopsisCCMEE171) and an alga (Chlorella ellipsoidea) were grown under simulated martian ecopoesisconditions. A xenon arc lamp with a solar filter provided simulated martian sunlight, and temperaturecycled diurnally from — 80 °C to 26 °C. A Mars-like atmosphere of 100 % CO_2was provided at 50, 100,300, 500 and 1000 mbar. The cyanobacteria and alga were inoculated into JSC Mars-1 soil simulant andexposed to each atmospheric pressure for five weeks. Survival and growth were determined viaextractable chlorophyll a and total esterase (fluorescein diacetate hydrolysis) activity. Maximumsurvival occurred at 100 and 300 mbar. At 50, 500 and 1000 mbar, esterase activity was near zero, andextractable chlorophyll a was less than 10 % of control samples. Overall, the cyanobacteria survivedbetter than the alga. Low survival at 50 mbar was probably due to desiccation. Low survival at 500 and1000 mbar may have been due to CO2 toxicity.