Optimization of expression conditions of an induction strategy for improving liver targeted interferon (IFN-CSP) production in E. coli / 生物医学工程学杂志

ABSTRACT

Expression conditions of induction strategies for the cytoplasmic inclusion bodies (IBs) production of liver targeted interferon IFN-CSP by recombinant Escherichia coli (E. coli) BL21 (DE3) were optimized in shake-flask cultures in this study. The factors of the optimized protocol included in the present study were pH, inducer IPTG (isopropyl beta-D-thiogalactoside) concentration, culture growth temperature, incubation time and induction point. The effects of those factors were investigated by 'single variable at a time' method, aimed to analyze characterization of the recombinant strain. Orthogonal experimental design was further used to optimize the above critical factors for IFN-CSP production. According to the expression optimization result, it was confirmed that the main influence factors were cell density and induction temperature. The IFN-CSP gene expression optimized conditions were pH value of the culture medium was 6.0, culture temperature 37 degrees C, adding IPTG to final concentration 0.4 mmol/L when the recombinant strain growth density OD600 achieved 0.8 and induction time 4 h. At this point, the IBs represented 74.3% of the total cellular protein. Compared with the non-optimized condition, IFN-CSP production obtained in optimized induction strategies were increased by approx. 1.2-fold. The optimized induction strategy yielded 688.8 mg/L of IFN-CSP, providing experimental data to study the biology activity and productive technology of IFN-CSP.