Succinic acid production by Actinobacillus succinogenes using acid and enzymatic hydrolysates of potato and beer wastes and repeated batch operation

The replacement of fossil resources by biomass is one of the key strategies for the development of bioeconomy. Here we have focused on the bioproduction of succinic acid, a biorefinery platform of great versatility and importance. In this study, the anaerobic bacterium Actinobacillus succinogenes was selected as the biocatalyst, choosing discarded potatoes and spent brewer's yeast hydrolysates served as carbon and nitrogen sources, respectively. The use of food residues is critical to reduce operating expenses in this type of processes. Furthermore, to analyze and improve the process performance, repeated batch fermentations were carried out in several conditions: with potato waste hydrolysate or 40 g L-1 of pure glucose as carbon sources and spent brewer's yeast hydrolysate or commercial yeast extract as nitrogen sources. Very promising results were obtained with the residue preparations: 35.8 g L-1 of succinic acid were produced, with a yield of 0.84 g g-1 and an average productivity of 1.19 g L-1 h -1, increasing the selectivity towards the target acid in comparison to pure glucose and yeast extract. Finally, a previously developed unstructured non-segregated global kinetic model is successfully applied, obtaining the parameters values in all conditions.