Optimization of Recombinant β-NGF Production in Bioreactor

Nerve growth factor (β-NGF) is an important therapeutic agent for the treatment of neurodegenerative diseases such as Alzheimer’s disease; so, recombinant production of it in industrial scale is of high importance. The aim of this study is to optimize the effective factors in achieving the highest rate of β-NGF protein production in the bioreactor. As E. coli is a suitable host for industrial production of recombinant proteins, E. coli DE3 strain was used for production of recombinant β-NGF. Also, fermentation was performed in a 5-L bioreactor and % dissolved oxygen (%DO) and post-induction temperature values were optimized by response surface methodology (RSM). At first, the effects of these two variables on the level of total protein were studied. So, in every experiment, bacterial proteins were isolated and total protein concentration was determined by Bradford assay. The results indicated that %DO and post-induction temperature of 30% and 28.5ºC were the best values for increased production of total protein; in these circumstances, total protein concentration was 9.6±0.61 mg/ml. Finally, the effects of these variables on recombinant β-NGF production were surveyed by dot blot analysis, indicating the maximum β-NGF expression level on the optimized condition. In conclusion, %DO and post-induction temperature not only affect cell growth of recombinant E. coli, but also have a direct impact on recombinant protein expression and production, such as β-NGF.