PROTEIN RECOVERY FROM BACTERIAL-CELL DEBRIS USING CROSS-FLOW MICROFILTRATION WITH BACKPULSING

Protein recovery from a bacterial lysate was accomplished using crossf low microfiltration with rapid backpulsing. The net flux with backpuls ing was found to increase with increasing forward and backpulse pressu res, increase to a maximum and then decrease with increasing forward f iltration time between backpulses (or decreasing backpulse frequency), increase weakly with increasing shear rate, and decrease strongly wit h increasing concentration in the feed. Variation of the operating con ditions for a dilute feed of 0.0025 g cell debris/g suspension on a we t cell mass basis yielded net flux values as high as 4.5 X 10(-3) cm/s (160 l/m(2) h) with backpulsing, compared to a steady-state value of 4.0 X 10(-4) cm/s (14 l/m(2) h) for similar conditions without backpul sing. The optimal backpulse frequency was found to be very high, about 2.5 times per second, for the minimum backpulse duration of 0.09 s. H owever, the performance of the backpulsing operation declined with inc reasing concentration of cell debris, with no flux improvement achieve d for concentrations greater than 0.01 g cell debris/g suspension. Nev ertheless, 100% protein transmission with backpulsing was achieved for all conditions investigated, compared to an average value of 60% tran smission in the absence of backpulsing. Thus, rapid backpulsing is an effective method for the recovery of protein from dilute cell debris.