High-level expression of soluble human epidermal growth factor in Escherichia coli

Abstract Human epidermal growth factor (hEGF) has multiple biological functions, and it is a very expensive polypeptide with attractive market prospects. However, the production of hEGF needs for high cost to manufacture polypeptide demands reinvestigations of process conditions so as to enhance economic benefits. Improving the expression of soluble hEGF is the fundamental method to reduce the cost. In this study, a non-secretion engineered strain of biosynthesized hEGF was constructed, using plasmid pET-22b(+) in Escherichia coli. Preliminary fermentation and high cell density cultivation were carried out in shake flasks and in a 5 L bioreactor, respectively. A high yield of 98 ± 10 mg/L of soluble hEGF and a dry cell weight (DCW) of 6.98 ± 0.3 g/L were achieved in shake flasks. Then, fermentation conditions were optimized for large-scale production, while taking into consideration the expensive equipment required for cooling and conforming to industrial standards. A yield of 285 ± 10 mg/L of soluble hEGF, a final cell density of 57.4 ± 2 g/L DCW (OD600 = 141.1 ± 4.9), and hEGF productivity of 14.3 mg/L/h were obtained using a bioreactor at 32 ℃ for 20 h. The production method developed in this study for the biosynthesis of soluble hEGF is efficient and inexpensive.