Succinic acid production from xylose-enriched biorefinery streams by Actinobacillus succinogenes

Succinic acid (SA) is a potential platform chemical that can be produced from lignocellulosic sugars, and the development of a cost-competitive, fermentation-based SA production system is gaining significant attention in modern biorefineries. In the current work, we evaluated SA production from xylose-enriched streams from dilute acid pretreated corn stover. In particular, the streams of interest consisted of xylose (~100 g/L), glucose (~14 g/L), galactose (~7 g/L), arabinose (~16 g/L), and inhibitors derived from the pretreatment such as furfural (~1.8 g/L), hydroxymethylfurfural (HMF) (~0.3 g/L), and acetates (4 g/L and 11 g/L in previously deacetylated (DCS) or non-deacetylated (AS) corn stover). Actinobacillus succinogenes 130Z, a facultative anaerobic, biofilm-forming SA producer, was selected for this study. Using batch fermentation, we first determined the inhibition effect of xylose levels on SA production. Secondly, we studied the effect of furfural, HMF, and acetate in mock DCS- and AS-hydrolysates, and lastly, we used actual hydrolysates. SA was produced in all fermentation broths for both mock and actual AS- and DCS-hydrolysates, and titers, rates, and yields will be reported for each scenario. The optimal xylose concentration was determined to be 60 g/L, and acetate seemed to be the major inhibitor of SA production, above furfural and HMF. Going forward, strain development and improvement of the culture conditions will be conducted in order to enhance SA production from biomass-derived sugars.