Microbial production of C4 dicarboxylic acids

Authors: Terrell, Evan; Bruni, Gillian

Submitted to: Scholarly Community Encyclopedia
Publication Type: Literature Review
Publication Acceptance Date: 5/19/2022
Publication Date: 5/19/2022
Citation: Terrell, E., Bruni, G.O. 2022. Microbial production of C4 dicarboxylic acids. Scholarly Community Encyclopedia. Available: https://encyclopedia.pub/entry/23082.

Interpretive Summary: One group of chemicals that have a wide variety of potential applications is known as "C4 dicarboxylic acids." These types of acids (spefically: succinic, malic, and fumaric acid) can be produced by microbes like bacteria and yeasts. Further, these microbes can utilize waste and/or by-products from sugar crop processing to make the compounds of interest. Overall, this creates a more efficient process and presents an opportunity to generate useful chemicals from waste materials. Once C4 dicarboxylic acids are produced, they may be utilized in foods, cosmetics, biofuels, biochemicals, and other potentially attractive green industries.

Technical Abstract: A major contributor to the final cost for a biomass-derived product is typically the cost of the initial biomass feedstock. To overcome this economically driven obstacle, the effective utilization of biomass-derived wastes and by-products is critical. Using wastes is desirable because they are abundantly available at low cost, with the intrinsic benefit of affording new waste management opportunities. One class of compounds that is readily derivable from microbial conversions of biomass-derived feedstocks is C4 dicarboxylic acids; specifically, these are succinic (butanedioic acid), fumaric (trans-butenedioic acid), and malic (hydroxybutanedioic acid) acids. In order to make bio-based production of high value C4 dicarboxylic acids competitive and more economically feasible compared to fossil fuel-based production, it is imperative that microbial conversion of inexpensive biomass be optimized. Part of this process may involve metabolic engineering of strains, adaptation to inexpensive feedstocks, exporter engineering, and process development which includes optimization of aeration, pH, temperature, and isolation/purification steps. Microbial production of valuable, bio-based C4 dicarboxylic acids such as malic acid and succinic acid is performed primarily by filamentous fungi and anaerobic bacteria as well as yeast such as S. cerevisiae. In S. cerevisiae, the C4 dicarboxylic acids can be produced either in the cytosol by the reductive TCA branch or through modification of the mitochondrial TCA cycle. Collectively, a diverse variety of strategies have been implemented to augment C4 dicarboxylic acid production, consideration of which may benefit and improve aspects of future studies.