Growth and survival of filamentous cyanobacteria under Martian surface conditions

Cyanobacteria are oxygenic phototrophs with significant potential in space exploration, as they are adept at producing two of the most relevant resources outside Earth: oxygen and organic matter. These microorganisms may be of use in colonizing planetary bodies in the solar system. To assess the adaptability and resilience of these organisms under deleterious conditions, we used several Martian regolith simulants to support the growth of three widespread filamentous cyanobacteria (Desmonostoc muscorum UTAD N213, Anabaena cylindrica UTAD A212 and an uncharacterized Desmonostoc sp.) Both MGS-1 and MMS-2 were fully colonized by all cyanobacteria, and soluble minerals present within them were enough to allow and sustain significant growth. The resistance of the two Desmonostoc species to desiccation and UV radiation was also assayed in all Martian regolith simulants, and in two clays: Montmorillonite and nontronite. Desiccation hindered growth, but both cyanobacteria were able to recover in less than 30 days in all cases after desiccation. Short irradiation times (up to 1000 kJ/m2) did not consistently affect survival, but longer ones (24,000 kJ/m2) could fully destroy all cyanobacteria in some samples. Cyanobacteria within MGS-1, montmorillonite and nontronite, however, showed signs of recovery in the long term (>70 days). Clays were also remarkably effective at preserving cyanobacterial viability. This was particularly the case for montmorillonite.