Assistant Professor University of California, Riverside Riverside, California
Crops grown during space expeditions can provide a fresh source of food and nutrients, carbon dioxide uptake capacity, and behavioral health benefits to crewmembers. However, the physical space and energy inputs available for crop growth are severely limited during space flight. Food production in a space flight environment is ultimately constrained by the energy conversion efficiency of photosynthesis which can be low (only a few percent). Increasing the energy efficiency of food production would allow for more food to be produced using less resources. Artificial photosynthesis seeks to overcome the limitations of biological photosynthesis, including low efficiency of solar energy capture and poor carbon dioxide reduction, and could provide an alternative route for food production. In this talk I will describe our work to decouple food production from photosynthesis through the development of a hybrid inorganic–biological system for the cultivation of food producing organisms. A two-step electrochemical process converts CO2 to acetate, which serves as a carbon and energy source for the heterotrophic cultivation of food producing organisms. We have demonstrated the cultivation of yeast, mushroom-producing fungus and a photosynthetic green alga, all in the dark without inputs from biological photosynthesis. An evaluation of nine crop plants found that carbon from exogenously supplied acetate incorporated into biomass through major metabolic pathways but could not natively sustain the growth of these plants. Metabolic engineering efforts are underway to enable heterotrophic growth on acetate as the sole carbon and energy source. Coupling this artificial photosynthesis approach to existing photovoltaic systems could increase solar-to-food energy conversion efficiency by about fourfold over biological photosynthesis, reducing the solar footprint required. This technology allows for a reimagination of how food can be produced in controlled environments.