Absence of increased genomic variants in the cyanobacterium Chroococcidiopsis exposed to Mars‐like conditions outside the space station

Despite the increasing interest in using microbial‐based technologies to support human space exploration, many unknowns remain not only on bioprocesses but also on microbial survivability and genetic stability under non‐Earth conditions. Here the desert cyanobacterium Chroococcidiopsis sp. CCMEE 029 was investigated for robustness of the repair capability of DNA lesions accumulated under Mars‐like conditions (UV radiation and atmosphere) simulated in low Earth orbit using the EXPOSE‐R2 facility installed outside the International Space Station. Genomic alterations were determined in a space‐derivate of Chroococcidiopsis sp. CCMEE 029 obtained upon reactivation on Earth of the space‐exposed cells. Comparative analysis of whole‐genome sequences showed no increased variant numbers in the space‐derivate compared to triplicates of the reference strain maintained on the ground. This result advanced cyanobacteria‐based technologies to support human space exploration.