AUTHOR=Xiberras Joeline , Klein Mathias , de Hulster Erik , Mans Robert , Nevoigt Elke 

TITLE=Engineering Saccharomyces cerevisiae for Succinic Acid Production From Glycerol and Carbon Dioxide

JOURNAL=Frontiers in Bioengineering and Biotechnology

VOLUME=8

YEAR=2020

URL=https://www.frontiersin.org/journals/bioengineering-and-biotechnology/articles/10.3389/fbioe.2020.00566

DOI=10.3389/fbioe.2020.00566

ISSN=2296-4185

ABSTRACT=<p>Previously, our lab replaced the endogenous FAD-dependent pathway for glycerol catabolism in <italic>S. cerevisiae</italic> by the synthetic NAD-dependent dihydroxyacetone (DHA) pathway. The respective modifications allow the full exploitation of glycerol’s higher reducing power (compared to sugars) for the production of the platform chemical succinic acid (SA) via a reductive, carbon dioxide fixing and redox-neutral pathway in a production host robust for organic acid production. Expression cassettes for three enzymes converting oxaloacetate to SA in the cytosol (“SA module”) were integrated into the genome of <italic>UBR2</italic><sub>CBS</sub>-DHA, an optimized CEN.PK derivative. Together with the additional expression of the heterologous dicarboxylic acid transporter DCT-02 from <italic>Aspergillus niger</italic>, a maximum SA titer of 10.7 g/L and a yield of 0.22 ± 0.01 g/g glycerol was achieved in shake flask (batch) cultures. Characterization of the constructed strain under controlled conditions in a bioreactor supplying additional carbon dioxide revealed that the carbon balance was closed to 96%. Interestingly, the results of the current study indicate that the artificial “SA module” and endogenous pathways contribute to the SA production in a highly synergistic manner.</p>