Overcoming acetate in recombinant protein production by metabolic engineering of Escherichia coli

The primary goal of this research is to understand the physiological cause for overflow metabolism of E. coli in order to improve the yield and productivity of protein production. E. coli strains with genetic modifications (pyc+, pps+ and poxB-) at pyruvate node were examined. All these strains were grown in glucose-limited fed-batch with defined medium at two different growth rates: 0.15 h-1 and 0.35h-1. More protein and less acetate were produced at low growth rate. Overexpression pyc improves protein yield at low growth rate. Overexpression of pps did not improve protein production but increased glucose uptake rate. Knockout poxB has a detrimental impact on protein production. Protein production in poxB- strain containing pyc or pps decreased significantly compared to the strain containing pyc or pps alone. The intracellular pyruvate/PEP ratio was essentially unchanged between low and high growth rate.