Effects of immobilization of Actinobacillus succinogenes on efficiency of bio-succinic acid production from glycerol

Abstract

The aim of this research was to optimize bio-succinic acid production from glycerol by using Actinobacillus succinogenes. The effects of different substrate types (pure and crude glycerol), cell patterns (free cells and immobilized cells in agar), and carbonate sources (MgCO3 and CaCO3) on succinic (SA) production were studied in serum bottles. The maximum succinic acid concentration of 8.9 ± 0.5 g/L and yield of 1.27 g SA/g GLR were achieved using crude glycerol fermentation by immobilized cells supplemented with10 g/L of MgCO3 to increase dissolved CO2 in the system. However, a high concentration of MgCO3 (20 g/L) resulted in an adverse effect on SA production due to increasing pH which decreased CO2 fixation in the C4 pathway. The optimal conditions were used for up-scaling SA fermentation in a 1-L bioreactor using batch and semi-continuous operations. Higher SA concentration, glycerol utilization, and SA yield of 10.8 g/L, 88.8%w/w, and 1.25 g SA/g GLR, respectively, were achieved using the batch process. The development process is potent for further up-scaling the study for SA production.