Proteomics of long-term acclimation of the desert cyanobacterium Chroococcidiopsis sp. CCMEE 029 in perchlorate-rich medium and its implications for in situ resource utilization on Mars.

Space exploration demands sustainable technologies to minimize reliance on Earth-based resources. The extreme-tolerant cyanobacterium Chroococcidiopsis sp. CCMEE 029 exhibits remarkable resistance to perchlorate salts ubiquitously found on Martian soil, holding promise for in situ resource utilization. Exploring the proteomic responses to this chaotropic agent is fundamental for understanding the mechanisms of salt-stress response in cyanobacteria and to develop biotechnologies based on local resources to support human outposts. Hence, using liquid chromatography-tandem mass spectrometry, we analyzed the protein expression after 21 days of cultivation in the presence of increasing perchlorate concentrations with triplicates per experimental condition (|log2FC| ≥ 0.5; FDR ≤ 0.05). This study shows that this cyanobacterium displays a broad suite of enzymatic and non-enzymatic mechanisms for mitigating reactive oxygen species, as well as formaldehyde assimilation capacity from the RuMP pathway. The upregulation of polyhydroxybutyrate and siderophore biosynthesis further supports its suitability for putative bioplastic production, nutrient mobilization, and plant protection in extraterrestrial environments. Overall, Chroococcidiopsis sp. CCMEE 029 modulates its metabolism to maintain energy balance, support growth, and synthesize biotechnologically relevant compounds. This versatility underscores its suitability as a candidate for Martian bioprocessing, where robustness, low resource requirements and multifunctionality are paramount. By providing molecular insights into cyanobacterial stress responses, this research advances our understanding of microbial adaptation to environmental constraints occurring on Mars and lays the groundwork for optimizing microbial biotechnologies to support astronauts in long-term missions on the red planet.