To generate air to breathe on Mars, research is being conducted on cyanobacteria to see if they can photosynthesize at low pressure. CyprienVerseux is conducting research on cyanobacteria at ZARM under simulated Martian conditions.
MAPEX Research Highlight: https://www.uni-bremen.de/en/mapex/research/research-highlights/mapex-research-highlights/a-low-pressure-n2-co2-atmosphere-is-suitable-for-cyanobacterium-based-life-support-systems-on-mars