High-level secretory production of human granulocyte-colony stimulating factor by fed-batch culture of recombinant Escherichia coli

Secretory production of human granulocyte colony-stimulating factor fusion protein (hG-CSF) by fed-batch culture of Escherichia coli was investigated in both 2.5-L and 30-L fermentors, To develop a fed-batch culture condition that allows efficient production of hG-CSF, different feeding strategies including pH-stat, exponential and constant feeding were examined. Among these, the constant feeding strategy (0.228 g glucosexmin(-1)) and the exponential feeding that supports a low specific growth rate (mu=0.116 h(-1)) resulted in the best hG-CSF production. Under these conditions, 4.4 gxL(-1) of hG-CSF was produced. The effect of induction time on the protein production was also investigated. For the fed-batch cultures carried out with the pH-stat and exponential feeding strategies, induction at higher cell density (late-exponential phase) resulted in more hG-CSF production compared with induction at lower cell density (early to mid-exponential phase). The constant feeding strategy that supported best hG-CSF production was applied to the scale-up production of hG-CSF in 30 L of fermentor. The maximum dry cell weight and hG-CSF concentration of 51.7 and 4.2 gxL(-1), respectively, was obtained.