Integrated succinic acid production from xylose-enriched hydrolysates by Actinobacillus succinogenes for downstream biopolymer production

The production of chemicals from biomass alongside fuels will enable the economic feasibility of modern biorefineries. Succinic acid (SA), a C4-dicarboxylic acid, 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, a facultative anaerobic, capnophilic, genetically tractable bacterium, making it an attractive target for industrial production. In the current study, a high-xylose content hydrolysate from deacetylated, dilute-acid pretreated corn stover (DDAPH) was investigated for the production of SA. A. succinogenes efficiently utilized most of the sugars in DDAPH (i.e. glucose, xylose, arabinose, and galactose) producing SA titers up to 39 g/L from initial 60 g/L of sugars in anaerobic batch-fermentation. Interestingly, A. succinogenes also detoxified the hydrolysate prior to SA production, via reduction of furfural to its corresponding alcohol. SA yields of 0.74 g/g sugars and maximum productivities of 1.27 g/L-h were achieved. Downstream separation has been also performed to recover SA from the fermentation broth, and the resulting SA has been catalytically converted to 1,4-butanediol (1,4-BDO). In addition, the bio-derived SA and 1,4-BDO have been polymerized to produce bio-poly(butylene succinate) (bio-PBS), which presents comparable thermal properties and  molecular weights to that produced from commercial SA. This work paves the way to further strain and fermentation development as well as biochemical integration for the production of bio-polymers from lignocellulosic biomass.