Key Limiting Factors for the Whole-Cell Synthesis of N-Acetyl Neuraminic Acid by Recombinant Escherichia coli

Abstract:

We constructed a recombinant Escherichia coli which could synthesize Neu5Ac with exogenous GlcNAc as sole substrate in previous work. Various nitrogen and carbon sources were used to investigate their effects on the production of Neu5Ac，and the key limiting factors in fluencing the whole process were revealed. It was shown that the increase of NeuB activity could not improve the Neu5Ac yield and the NeuB activity was not the limiting factor. The intracellular PEP was supposed to be the limiting factor for Neu5Ac production. The intracellular PEP was saved and shifted to the synthesis of Neu5Ac by adjusting the nitrogen source and restraining the cell growth. In addition，by using glycerol as sole carbon source which was PTS-independent，Neu5Ac synthesis in the glycerol/nitrogen-free medium reached （4.42±0.08） g/L，10.3 times higher than the initial synthesis conditions.