Optimization of human interferon gamma production in <Emphasis Type="Italic">Escherichia coli</Emphasis> by response surface methodology

The production of human interferon gamma (hIFN-γ) using a synthetic gene in Escherichia coli BL21-SI was optimized by response surface methodology (RSM) and a Box-Behnken design. The process variables studied were temperature, bio-mass concentration at induction time and the NaCl concentration as inducer. According to the Box-Behnken design, a second order response function was developed. The optimal expression conditions were a temperature of 32.6°C, induction biomass of 0.31 g/L and 0.3 M NaCl in minimal medium. The model prediction for the maximum hIFN-γ production was 77.3 mg/L, which corresponded satisfactorily with the experimental data. The hIFN-γ concentration attained under optimized conditions was 13-times higher than that obtained using the non-optimized conditions. We conclude that RSM is an effective method for the optimization of recombinant protein expression using synthetic genes in E. coli.