Towards new carbon-neutral food systems: Combining carbon capture and utilization with microbial protein production

Alternative protein sources such as microbial protein (MP) are currently considered to alleviate the burden that food production exerts on the environment. Even though MP production is highly efficient in land and nutrient utilization, their carbon footprint should be improved. Here we propose the use of CCU as a driver for heterotrophic MP production. By comparing different MP production routes starting from liquid substrates derived from CO₂ (i.e., formate, acetate, methanol, and ethanol) and their respective metabolic pathways, the potential of this concept as a carbon-neutral food or feed production process was estimated. Acetate and ethanol appear to be the most beneficial substrates for the integrated CCU-to-MP process in terms of electricity demand (acetate: 25 - 54 kWh/kg_product, ethanol: 28 - 56 kWh/kg_product). Moreover, recycling CO₂ enables a carbon-negative protein production process by 2030 (considering the projected CO₂ emissions from electricity in the EU: 0.096 kg_CO2-eq/kWh) for formate, acetate, and ethanol (-1.1 up to 13 kg_CO2-eq/kg_product).