BACKGROUND: A sustained presence on Mars requires the production of food on site, but farming is limited by the local availability of suitable nutrients. Cyanobacteria can feed on Martian resources, and we hypothesized that the nutrients they mobilize could be extracted through anaerobic digestion and used as crop fertilizer. METHODS: We therefore tested the abilities of three microbial communities to digest the biomass of Anabaena sp. in minimal medium, 200 g L RESULTS: All communities produced ammonium and removed organic carbon in all media, especially in minimal medium and 200 g L IMPACT: Overall, this study suggests the viability of a bioprocess which could support crop production from Martian resources.