High pressure homogenization is a key unit operation in inclusion body processing.

Recombinant protein production in E. coli often leads to the formation of inclusion bodies (IBs). Although downstream processing of IBs has the reputation of being a great hurdle, advantages of IBs can be substantial. Highly pure recombinant protein with the possibility of correctly folded structures and an easy separation from cell matter are decisive factors that make IB processes so interesting. Product yield, purity and biological activity of the refolded protein are the responses to evaluate an IB process. The objective of this case study was to develop a refolding process in an integrated manner. The effects of the unit operations 1) homogenization, 2) IB wash and 3) IB solubilisation as well as their interdependencies were analyzed. We revealed interesting factor interactions between homogenization and IB wash, as well as homogenization and solubilisation, which would be overlooked if the single unit operations were investigated individually. Furthermore, we found that homogenization was a key unit operation for IB processing. By changing the conditions during homogenization only, the product yield, purity and biological activity of the refolded product was affected 2-fold, 1.2-fold and 2.5-fold, respectively.