High-efficiency production of succinic acid from glycerol by metabolically engineered Escherichia coli

To construct a high-yield succinate producing strain,the recombinant strain Escherichia coli CICIM B0013-025 lacking genes ackA-pta,ldhA and pflB served as the starting strain.The promoter of phosphoenolpyruvate carboxylase in this bacterium was then replaced by the temperature-inducible promoter P_L and P_R of lambda phage,generating the thermoregulatory succinic acid-producing strain B0013-026.After optimization,a dual-phase fermentation process was established as follows:the temperature used for cell growth and induction was 37 ℃ and 42 ℃,respectively;succinic acid was produced under micro-aerobic condition,with glycerol and 5 g/L of tryptone as the sole carbon source and organic nitrogen,respectively.After cultured in a 5 L fermentor under optimal conditions,the succinate titer,overall productivity and conversion rate of glycerol reached 62.5 g/L,1.04 g/(L·h)and 64.2%,with only small amounts of α-ketoglutaric acid(3.0 g/L)and acetate(1.8 g/L)accumulated.Therefore,using glycerol as the sole carbon source,we achieved the efficient production of succinic acid,providing an important reference for its industrial production.