(438i) Flocculation Enhanced Centrifugation and Microfiltration of Escherichia Coli Lysate

Centrifugation and microfiltration are two commonly used downstream separation processes in biotechnology industry to separate cells and cell debris from target products, such as proteins. Because of the high dependency of these two processes on the particle size and particle size distribution in the feed solution, their performance could be significantly improved if the cells and cell debris were flocculated. In this study, four different series of polymeric flocculants, including polyamines, poly(diallyldimethylammonium chloride), Mannich polyacrylamides, and quaternary Mannich-acrylamide copolymers, have been used to flocculate an Escherichia coli lysate. The optimum dosage, which gives the lowest obsorbance at 600 nm after flocculation, has been measured for each flocculant. The effects of the charge density and molecular weight of each series of flocculants on the optimum dosage have been analyzed. Further, the performance of the centrifugation and microfiltration of the E. coli lysate, with and without flocculation, has been investigated and compared. The results show that by choosing an appropriate polymeric flocculant and dosage, both of the centrifugation and microfiltration separations could be significantly enhanced.

Keywords: Flocculation, Centrifugation, Microfiltration, Polymeric flocculant, Optimum dosage