Enhanced Production of Insulin-Like Growth Factor I Protein in Escherichia coli by optimization of five key factors

Human insulin-like growth factor I (hIGF-I) is a kind of growth factor with clinical significance in medicine. The major objective of this study is over- production of recombinant human insulin-like growth factor I(rhIGF-I) through a developed process by recruiting effective factors in order to achieve the most recombinant protein. Up to now E. coli expression system has been widely used as a host to produce rhIGF-1 with high yields. Batch cultures as non-continuous fermentation were carried out to overproduce rhIGF-I in E. coli. The effects of culture medium type, induction temperature and amount of inducer on cell growth and IGF-I production were investigated in shaking flask. Taguchi design of experiments (DOE) method was used as the statistical method. Analysis of experimental data showed that maximum production of rhIGF-I was occurred in 32y culture medium at 28°C and 0.05 Mm IPTG. Under this condition, 0.7 g/L of rhIGF-I was produced as the inclusion bodies. Following optimization of these three factors, we have also optimized the amount of glucose and induction time in 5 liter top bench bioreactor. Full factorial design of experiment method was used for these two factors as the statistical method. 10 g/l and OD600=5 were selected as the optimum point of Glucose amount and induction time, respectively. Finally we have had 1.26 g/l rhIGF-1 production as the final product that is one of the best reported amounts.