Optimization of succinic acid production from cane molasses by Actinobacillus succinogenes GXAS137 using response surface methodology (RSM)

A method combining a Plackett-Burman design (PBD), the steepest ascent method (SA), and a Box-Behnken design (BBD) was developed to optimize succinic acid production from cane molasses by Actinobacillus succinogenes GXAS137. The important parameters were (g/L): total sugars of cane molasses (85 g/L), yeast extract (8.84 g/L), and MgCO3 (63.1 g/L). Verification experiments indicated that the maximal succinic acid production reached 57.43 +/- 0.86 g/L, which agreed with the predicted value (57.12 g/L). In addition, batch and fed-batch fermentations were carried out in a 1.3 L stirred bioreactor. Compared with a batch fermentation that produced 57.96 g/L of succinic acid at 60 h, a fed-batch fermentation, performed to minimize the inhibition effect of the substrate, produced 64.34 g/L of succinic acid at 60 h. The combined method is powerful for selection of optimized conditions for succinic acid production from cane molasses.