Laboratory bench-scale and pilot plant scale-up processes were established and characterized for Pichia pastoris disruption in a bead mill after fermentation in methanol. Combinations of retention times per pass and number of passes were evaluated. Heat generation during wet milling was evaluated and the thermal balance of the operation yielded a clear correlation between generated heat and retention time. Under these conditions, approximately 66% and 34% of the heat generated during the process was removed by the refrigerant and the product, respectively. Rheological properties of the process fluids were determined and a change from Newtonian to a non-Newtonian behaviour was observed as disruption progressed. The relation between changes in rheology and product temperature rises suggested that the most effective method for P. pastoris cell disruption is by a single pass of 6 min through the mill.

This work was funded in part by The Welcome Trust project 075799.

Peer reviewed