Comparative study of succinic acid production from xylose-enriched biorefinery streams by Actinobacillus succinogenes and Basfia succiniciproducens in batch fermentation

The production of chemicals from biomass alongside fuels will likely enhance the economic feasibility of modern biorefineries, and succinic acid (SA) is one such value-added co-product that could be used to this end. SA is found as major metabolic intermediate in some prokaryotic organisms such as Actinobacillus succinogenes and Basfia succiniciproducens. Additionally, these bacteria are non-pathogen, facultative anaerobic, and genetically tractable, features that make them attractive targets for industrial purposes. In the current study, a high-xylose content hydrolysate from deacetylated diluted acid pretreated corn stover (DDAPH) was investigated for the production of SA by both bacteria in batch fermentation. Fermentations were carried out in 0.5 L BioStat-Q Plus fermentors, at pH 6.8, 37°C and 300 rpm with CO₂ sparged at 0.03 vvm. A. succinogenes and B. succiniciproducens efficiently utilized most of the sugars in DDAPH (i.e. glucose, xylose, arabinose, and galactose) producing SA titers up to 43 and 30 g/L from initial 80 and 60 g/L of sugars respectively. Interestingly, both species detoxified the hydrolyzate before SA production started, via reduction of furfural to its corresponding alcohol. Yields of 0.74 and 0.68 g SA/g sugars and maximum productivities of 1.27 and 1.23 g SA/L-h were achieved in A. succinogenes and B. succiniciproducens, respectively. Yield decreases in the latter species were mainly due to the production of lactic acid. This work will pave the way to further strain and fermentation engineering for the production of SA from lignocellulosic biomass.