Modeling and experimental assessment of Synechococcus nidulans cultivation using simulated Martian medium and astronauts’ urine

The growth of microalgae as food for astronauts is one of the main challenges in view of future manned missions on Mars. The possibility of cultivating the cyanobacterium Synechococcus nidulans in a medium consisting of a mixture of simulated regolith leachate and astronauts’ urine, called Martian Medium, is investigated with the aim of reducing the payload deriving from nutrients to bring from Earth. The strain was capable of surviving and grow with a biomass productivity of about 29 g m−3 day−1 in a medium containing 40% v/v of Martian Medium and urine. The composition of the strain, showing a prevalence of proteins, was not affected by the Martian Medium content up to 60% v/v. The produced biomass was characterized by a good antioxidant power and a relevant content of carotenoids that, together with the biochemical composition, make this strain a potential food for astronauts. The experimental results were well simulated by a mathematical model considering the effect of CO2 level, light intensity, and Martian Medium content on the growth of the strain. Once validated, the model was used to predict the biomass productivities achievable when using Martian CO2 in pressurized domes hosting the culture. The model estimated that a pond of about 85 m2 and 40 cm deep hosted in CO2 pressurized domes might allow to meet the 40% of proteins astronauts’ needs during manned missions on Mars.