PROTEIN RECOVERY FROM CELL DEBRIS USING ROTARY AND TANGENTIAL CROSS-FLOW MICROFILTRATION

Protein recovery from a bacterial lysate was accomplished using microf iltration membranes in a flat crossflow filter and in a cylindrical ro tary filter. Severe membrane fouling yielded relatively low long-term permeate flux values of 10(-4)-10(-3) cm/s (where 1 cm/s = 3.6 x 10(4) L/m(2) - h). The permeate flux was found to be nearly independent of transmembrane pressure and to increase with increasing shear rate and decreasing solids concentration. The flux increased with shear to appr oximately the one-third power or greater for the flat filter and the o ne-half power or greater for the rotary filter; the stronger dependenc e for the rotary filter is thought to result from Taylor vortices enha ncing the back transport of debris carried to the membrane surface by the permeate flow. The average protein transmission or sieving coeffic ient was measured at approximately 0.6, but considerable scatter in th e transmission data was observed. The largest sieving coefficients wer e obtained for dilute suspensions at high shear rate. The rotary filte r provided higher fluxes than did the flat filter for dilute suspensio ns, but not for concentrated suspensions. (C) 1995 John Wiley and Sons , Inc.