Power-to-Vitamins: Producing Folate (Vitamin B9) from Renewable Electric Power and CO2 with a Microbial Protein System
Meeting a surging demand for superior micronutrient-rich protein sources and finding production practices that are less detrimental to the climate will be critical challenges of the 21st century. New technologies are needed to decouple food production from land use. Our group previously proposed a two-stage Power-to-Protein technology to produce microbial protein from renewable electric power and CO2. Two stages were operated in series: (1) Clostridium ljungdahlii in Stage A to utilize H2 to reduce CO2 into acetate; and (2) Saccharomyces cerevisiae in Stage B to utilize O2 and produce microbial protein from acetate. Renewable energy would power water electrolysis to produce H2 and O2. A disadvantage of C. ljungdahlii in Stage A is the need to continuously feed vitamins to sustain growth and acid production. Changing to the more robust thermophilic acetogen Thermoanaerobacter kivui avoids providing any vitamins. Additionally, S. cerevisiae produces folate when grown with acetate as a sole carbon source under aerobic conditions. A total folate concentration of 6.7 mg per 100 g biomass with an average biomass concentration of 3 g L-1 in Stage B is achieved. The developed Power-to-Vitamin system enables folate production from renewable power and CO2 with zero or negative net-carbon emissions.