(188am) Increase Recombinant Bax Expression By Inducing E.coli Cells at Oxygen Limiting Condition with a Constant kLa

Bax is a pro-apoptosis protein which translocates from the cytosol into mitochondria membrane upon initiation of programed cell death, subsequently disrupts mitochondria membrane and releases cytochrome C. Structure of Bax has been solved but the molecular mechanism of how it regulates apoptosis is still under intensive investigation. Recombinant Bax has been obtained by growing E.coli cell in a fermenter and inducing cells with IPTG, but the expression level varied substantially from batch to batch. A detailed study showed that oxygen level in the fermentation culture during induction period was the key to differed expression level. More specifically, Bax expression level decreased continuously when dissolved oxygen level was kept at 30% which is non-limiting for E.coli. Alternatively, when oxygen was limited (0 %) with a constant agitation or k_La, Bax expression level reached its highest after 5 hour induction and the yield increased by a factor of two. Short chain fatty acids were monitored closely with HPLC, and proteomic analysis was used to identify the mechanism behind the higher expression level

Keywords: Dissolved Oxygen in Fermentation, k_La in Fermenter, Recombinant Protein Expression, Proteomic Analysis