Valorization of the organic fraction of municipal solid waste for fumaric acid production and electrochemical membrane extraction using Candida blankii

This work focuses on valorization of waste streams as crude renewable resources in the frame of the circular bioeconomy for C4-carboxylic acid production by the natural yeast Candida blankii. The metabolism of Candida blankii was affected by the availability of air due to fermentation conditions (agitation, total fermentation volume) resulting in direction of the carbon flux towards biomass or competing C4-dicarboxylic acid production. The maximum C4-dicarboxylic acid production was 69.1 g/L (fumaric acid was 45.8 g/L, malic acid was 21.6 g/L and succinic acid was 1.7 g/L) with 0.19 g/g yield and 0.27 g/L/h productivity. Candida blankii was able to consume a wide range of commercial carbon sources. The utilization of the organic fraction municipal solid waste hydrolysate resulted in the production of 37.6 g/L C4-dicarboxyic acids. Furthermore, electrolytic membrane extraction was used for the purification of the organic acids resulting in the reduction of downstream, separation and purification steps.