Effects of immobilization ofActinobacillus succinogeneson efficiency of bio-succinic acid production from glycerol

The aim of this research was to optimize bio-succinic acid production from glycerol by usingActinobacillus succinogenes. The effects of different substrate types (pure and crude glycerol), cell patterns (free cells and immobilized cells in agar), and carbonate sources (MgCO(3)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 MgCO(3)to increase dissolved CO(2)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 CO(2)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.