Facilitating extracellular protein production in a novel E.coli strain via easily controlled process parameters

Abstract

Escherichia coli cells are a well established expression system for recombinant protein production. High cell densities and robust fermentation processes are only two of the many advantages of the E:coli expression host. However, one of their major disadvantages is complex downstream puri cation following cell disruption for intracellular product release. A conjunction between the simple and established fermentation process and the advantages of extracellular protein production could increase the applicability of E:coli expression systems for previously unfeasible applications. For this purpose the two easily controllable process parameters temperature and speci c growth rate were investigated for their impact on leakiness and cell lysis. Their impact on the two E:coli strains BL21(DE3) and the X-Press strain was compared. It was shown that both the speci c growth rate as well as the temperature have a positive impact on cell leakiness, furthermore, extracellular protein production was successfully decoupled from cell lysis. We saw that increasing the speci c growth rates also increased lysis while higher temperatures did not. Proposed process conditions for high extracellular product concentration coupled with high cell viabillity were shown to be at 35 C and 0.05 h􀀀1 speci c growth rate for the X-press strain and Protein A. The BL21(DE3) strain showed higher robustness in terms of lysis, combined with a lower ability for extracellular production.