Continuous succinic acid production from corn fiber hydrolysate by immobilized Actinobacillus succinogenes in a hollow fiber membrane packed-bed biofilm reactor

Succinic acid is one of the most useful intermediate chemicals that can be produced in a biorefinery approach. In this study, Actinobacillus succinogenes was immobilized to produce succinic acid using non-detoxified corn fiber hydrolysate (CFH) and a control mimicking the sugars in CFH. Tests were carried out in a hollow fiber membrane packed-bed biofilm reactor (HFM-PBR) operated in a continuous mode. Under steady-state conditions, the bioconversion process was characterized in terms of sugar consumption, succinic acid and other organic acid production. Steady states were obtained at dilution rates of 0.025, 0.05, 0.075, 0.1, 0.2, and 0.3 h(-1). The optimal results were achieved at the dilution rate of 0.05 h(-1) and recirculation rate of 50 ml/min with a maximum succinic acid concentration, yield and productivity of 31.1 g/L, 0.61 g/g and 1.56 g/L h, respectively, when control was used. Succinic acid concentration, yield and productivity of 23.4 g/L, 0.51 g/g and 1.17 g/L h, respectively, were obtained when CFH was used. Productivity in the HFM-PBR was between 1.3 and 1.9 times higher than productivities for succinic acid production from CFH stated in the literature. The results demonstrated that immobilized A. succinogenes has the potential for effective conversion of an inexpensive biomass feedstock to succinic acid. Furthermore, the process has the potential to serve as a means for value-added chemical biomanufacturing in an integrated corn biorefinery.