Power-to-Vitamins: Producing Folate (Vitamin B₉) from Renewable Electric Power and CO₂with a Microbial Protein System

Abstract

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 21stcentury. 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 operatedin series:(1)Clostridium ljungdahliiin Stage A to utilize H2 to reduce CO2 into acetate; and(2)Saccharomyces cerevisiaein Stage B to utilize O2 and produce microbial protein from acetate. Renewable energy would power water electrolysis to produce H2 and O2. A disadvantage ofC. ljungdahliiin Stage A is the need to continuously feed vitamins to sustain growth and acid production. Changing to the more robust thermophilic acetogenThermoanaerobacter kivuiavoids providing any vitamins. Additionally,S. cerevisiaeproduces 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-1in 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.