Maximizing Production of Human Interferon-γ in HCDC of Recombinant E. coli

Tuning recombinant protein expression is an approach which can be successfully employed for increasing the yield of recombinant protein production in high cell density cultures. On the other hand, most of the previous results reported the optimization induction conditions during batch and continuous culture of recombinant E. coli, and consequently fed-batch culture have received less attention. Hence, in this research induction conditions for the over-production of recombinant interferon-γ including the amount of inducer, induction time and post-induction duration during chemical induction were optimized. E. coli BL21 (DE3) (pET3a-hifnγ) was used to over-express human interferon-gamma (hIFN-γ) in an exponential fed-batch procedure with a maximum attainable specific growth rate of 0.55 h(-1) at the beginning of feeding and 0.4 h(-1) in induction time. The factors were considered as the amount of inducer (IPTG) in the range of 0.565-22 mg g(-1) L(-1) at seven levels, cell density at induction time as 53, 65 and 75 g (dry cell weight) L(-1), induction duration at different intervals of 3, 4, and 5 h after induction time. The final concentration of biomass and interferon gamma reached to 127 g L(-1) (DCW) and 51 g (hIFN-γ) L(-1) after 17 h, and also the final specific yield and overall productivity were obtained 0.4 g (hIFN-γ) g(-1) DCW and 3 g (hIFN-γ) L(-1) h(-1), respectively, which are the highest amounts of reported specific yield and productivity for recombinant proteins production.