Optimization of Fermentation Conditions for Recombinant Human Interferon Beta Production by Escherichia coli Using the Response Surface Methodology

Background: The periplasmic overexpression of recombinant human interferon beta (rhIFN-B)-1b using a synthetic gene in Escherichia coli BL21 (DE3) was optimized in shake flasks using Response Surface Methodology (RSM) based on the Box-Behnken Design (BBD). Objectives: This study aimed to predict and develop the optimal fermentation conditions for periplasmic expression of rhIFN-B-1b in shake flasks whilst keeping the acetate excretion as the lowest amount and exploit the best results condition for rhIFN-B in a bench top bioreactor. Materials and Methods: The process variables studied were the concentration of glucose as carbon source, cell density prior the induction (OD 600 nm) and induction temperature. Ultimately, a three-factor three-level BBD was employed during the optimization process. The rhIFN-B production and the acetate excretion served as the evaluated responses. Results: The proposed optimum fermentation condition consisted of 7.81 g L-1 glucose, OD 600 nm prior induction 1.66 and induction temperature of 30.27°C. The model prediction of 0.267 g L-1 of rhIFN-B and 0.961 g L-1 of acetate at the optimum conditions was verified experimentally as 0.255 g L-1 and 0.981 g L-1 of acetate. This agreement between the predicted and observed values confirmed the precision of the applied method to predict the optimum conditions. Conclusions: It can be concluded that the RSM is an effective method for the optimization of recombinant protein expression using synthetic genes in E. coli.