The potential of cyanobacterium Nostoc sp. as the primary producer in the life-support system on Mars

Abstract Background Cyanobacteria capable of photosynthesis and nitrogen fixation are considered to be the most promising primary producers of biological life-support systems for Mars exploration, but there is limited information about their survival and growth in space flight or Mars-like environments. Results During the HH-21-5 Balloon-Borne Astrobiology Platform flight mission of the Chinese Academy of Sciences, Nostoc sp. cells were exposed to the Mars-like environment in the stratosphere (35 km altitude) for 2 h in the Temperature-Controlled Biological Samples Exposure Payload. The results showed that the survival rate was high, although analyses did reveal some damage to the cellular metabolic activity and morphology of the experimental samples. Transcriptome analyses revealed that Nostoc sp. activated a set of defense mechanisms under Mars-like radiation levels, which included DNA repair, protein repair of the photosynthetic system, and antioxidant enzymes. Conclusions Results suggest that Nostoc sp. has the potential to survive and grow in Mars-like conditions and that it may be a suitable primary producer in future attempts to colonize Mars using cyanobacteria-based biological life-support systems with groundwater available.