Engineering Escherichia coli Tolerance to Improve Succinic Acid Production

Abstract:

[Objective] This study aims to enhance the high osmotic pressure tolerance of Escherichia coli (E. coli) for the efficient production of succinic acid.[Method] Adaptive evolution, transcriptomic analysis, reverse metabolic engineering, and fermentation optimization were employed for improving E. coli tolerance to high osmotic pressure.[Result] By analyzing the key factors influencing succinic acid production by fermentation, osmotic pressure was identified as the critical factor reducing succinic acid production efficiency . A mutant strain, E. coli FN-6, with tolerance to high osmotic pressure was obtained through adaptive evolution. The key gene cusC responsible for osmotic pressure tolerance was identified by transcriptomic analysis. After optimization of the expression level of cusC, the engineered strain E. coli FN-20 showed strong tolerance to high osmotic pressure. In a 5 L fermenter with E. coli FN-20, the succinic acid titer, yield, and productivity were up to 145.27 g/L, 90.0%, and 2.01 g/(L·h), respectively.[Conclusion] The obtained E. coli FN-20 strain with tolerance to high osmotic pressure enabled efficient production of succinic acid. This provides a new approach for the industrial production of succinic acid and provides the reference for producing other high value-added chemicals by fermentation.