Original Articles: 2016 Vol: 8 Issue: 6
Application of dissolved oxygen control and substrate feeding strategy to improve production of glutamate dehydrogenase protein of Streptococcus suis in Escherichia coli
The glutamate dehydrogenase (GDH) protein of Streptococcus suis is used for protecting pigs against S. suis infection, and acetate is a primary inhibitory metabolite in expression of GDH by E. coli and the expression of GDH was increased by reduction of acetate accumulation with optimization of dissolved oxygen (DO) level and feeding strategy. In this study, the effect of different DO levels and DO stage control strategies on expression of GDH were investigated, and the results indicated that the DO level controlled at 50% (0-5 h) and 30% (5- 10 h) decreased accumulation of acetate and increased cell density and GDH production. Furthermore, the DO and pH feedback feeding were applied in production of GDH, and higher cell density and concentration of GDH were obtained with DO feedback feeding that were 1.57 (OD600) and 38.24 mg/L and the accumulation of acetate decreased to 3.86 g/L. This study could provide theoretical foundation for industrial production of GDH and enhance the application market of GDH subunit vaccine.