Abstract: Objective: To explore the effect of IPTG concentrations on recombinant GroEL production in Escherichia Coli (E.coli) and analyze the reasons. Methods: The E. coli expression system for GroEL was constructed and induced by different IPTG concentrations (0, 10, 20, 30, 50, 100 μmol/L) for GroEL expression, and the SDS-PAGE and gel analysis software were used to determine the amount of expressed GroEL. The transmission electron microscopy (TEM) and OD-measuring were used to detect IB formation and bacterial growth. Results: GroEL mainly exists in the soluble form. The addition of IPTG can obviously increase the GroEL expression, and 30 μmol/L IPTG leaded to the most GroEL expression. Conclusion: The recombinant GroEL expression in E. coli differed among IPTG concentrations, and the optimal IPTG concentration was 30μmol/L. The main reasons for IPTG effect on GroEL yield were IB formation and growth inhibition.

Key words: Escherichia coli , Recombinant protein Isopropyl-β-D-thiogalactopyranoside