Slow post-induction specific growth rate enhances recombinant protein expression in Escherichia coli: Pramlintide multimer and ranibizumab production as case studies

Abstract

Specific growth rate (SGR) is a key process parameter that affects cell growth and recombinant protein expression in Escherichia coli (E. coli). Post induction, cell metabolism changes significantly due to the metabolic burden imposed by foreign protein expression and maintenance. Hence, post-induction SGR has a direct effect on heterologous protein expression. In this study, the effect of different post-induction SGR on the production of pramlintide multimer (rPramlintide) and ranibizumab using E. coli as the host was investigated. An exponential feeding strategy was used to control pre- and post-induction SGR. For all bioreactor runs, pre-induction SGR was controlled at 0.30 h−1. Among different post-induction SGR (0.3, 0.1, 0.08 and 0.04 h−1) values that were examined, SGR of 0.08 h−1 resulted in the highest rPramlintide titer accumulation of 4.49 g/L after 4 h of induction. For ranibizumab, the slowest post-induction SGR of 0.02 h−1 resulted in the highest light and heavy chain titer of 4.64 and 8.12 g/L, respectively. Results demonstrated that slow post-induction SGR improves the expression of heterologous proteins. The present study highlights a correlation between SGR and protein production and thus elucidates the importance of controlling post-induction SGR.