Improvement of fermentation density of aminotransferase by batch-feeding culture

Aminotransferase is a key enzyme for the enzymatic preparation of L-phenylalanine from phenylpyruvate. In order to improve the fermentation density of aminotransferase, the optimum batch-feeding culture technique of Escherichia coli A5 was studied. The initial glucose mass concentration was 5 g/L, the initial nitrogen resource was the mixture solution of 5 mL/L corn slurry and 1.5 g/L peptone, and the pH value of fermentation was controlled at 7.5. When the initial glucose mass concentration decreased to 2 g/L, the glucose content in the culture was controlled at this level by feeding 120 g/L glucose every 2 h. After 8 h of culture, the mixture solution with corn slurry 20 mL/L, peptone 6 g/L and the solution 0.6 g/L of four kinds of amino acid (L-methionine, L-valine, L-isoleucine, L-glutamic) were fed every 2 h. After 24 h culture under such conditions the mass concentration of dry cell of Escherichia coli A5 was up to 10.5 g/L, increased by 126% compared with the batch fermentation.