Enhanced succinic acid production and magnesium utilization by overexpression of magnesium transporter mgtA in Escherichia coli mutant

In this study, a novel engineered Escherichia coli strain KMG111 was constructed by overexpression of mgtA in E. coli mutant DC1515. By adopting KMG111, nearly a concentration of succinic acid (32.41 g L−1) with a yield of 0.81 g g−1 glucose, could be obtained in a batch fermentation by using the low-cost mixture of Mg(OH)2 and NH3·H2O to replace MgCO3 as the alkaline neutralizer. Moreover, the effect of the inhibitory compounds in lignocellulosic hydrolyzates on cell growth and succinic acid production could be relieved. In a 3-L bioreactor, the overall productivity and yield of succinic acid in the whole anaerobic stage were 2.15 g L−1 h−1 and 0.86 g g−1 total sugar, respectively. This study was the first to report decreased alkaline neutralizer cost via genetic manipulation for succinic acid production, which contributed to the industrialization of this microbial synthesis process.