Semi-continuous production of succinic acid from cane molasses by Actinobacillus succinogenes

In this work, the semi-continuous succinic acid fermentation by Actinobacillus succinogenes CGMCC1593 from cane molasses with a novel two-stage and two-stream system was studied, in order to increase the succinic acid productivity.The fermentation conditions of the first stage, such as initial sugar concentration, medium addition volume, and time interval of each loading were optimized.Under the optimized condition the maximum succinic acid productivity (2.38 g·L-1·h-1) was increased by 111% and 114% compared with those obtained in batch and fed batch fermentation, respectively.In addition, the maximum succinic acid concentration (46.0 g·L-1)increased by 12.9% compared with that in batch fermentation, and reached a compatible level of that obtained in fed batch fermentation (36 h, 48.8 g·L-1).This process was operated stably for 39 circles without any decreases in both succinic acid concentration and productivity.During the 39 operation circles, the fermentation time of each batch (stage 1 and stage 2), the average succinic acid concentration, succinic acid productivity, succinic acid yield, and sugar conversion rate were 21—24 h, 43.5 g·L-1, 2.07 g·L-1·h-1, 0.79 g·g-1, and 96.4%, respectively.