The Potential Anaerobic Cultivation of Microbial Biomass for Astronaut Nutrition During Long-Term Space Flight

Long-term crewed space missions will have significant constraints on the weight and volume of supplies. The food needed and the management of the waste produced present a challenge, demanding technologies that effectively recycle nutrients. Using microbiological processes may be a way to meet this challenge. Here, we suggest that byproducts of anaerobic wastewater digestion (organic acids, H₂, and CO₂) could be paired with waste CO from atmospheric regeneration to produce microbial biomass, specifically Acetobacterium woodii and Rubrivivax gelatinosus, as a food source. First, we showed that the thermodynamics of key reactions are favorable. Next, we conducted nutritional analyses to evaluate suitability of A. woodii and R. gelatinosus as potential food supplements. A. woodii biomass consisted of 21% protein and 11% lipid on a dry mass basis. R. gelatinosus biomass consisted of 54% protein and 21% lipid on a dry mass basis. Finally, we conducted growth experiments for R. gelatinosus under varied (ammonium) acetate concentrations. Following the observation that an intermediate amount of acetate produced the most biomass, a second growth experiment showed that a high level of acetate, rather than ammonium, wasthe observed inhibiting factor. This perspective hopefully inspires new research establishing systems where waste products are recycled via microbial growth during long-term space flight.