INFLUENCE OF STRAIN AND MEDIUM COMPOSITION ON FILTRATION OF ESCHERICHIA-COLI SUSPENSIONS

Cross-flow filtration of Escherichia coli strains was examined at the laboratory and pilot scales using Romicon 500,000 molecular-weight-cut off hollow fiber membranes. Both the series resistance and macrosolute polarizaton models were employed to compare performances. Total disso lved solids content above 90 g/L and viscosity above 1.1 x 10(-3) Pa . s of cell-free culture media were found to decrease average filtratio n fluxes by over 60% both in the absence and presence of cells. Broth filtrations with culture media of dissolved solids levels below 80 g/L were influenced to a greater extent by harvest cell density. The coll oidal nature of the complex nutrient responsible for the total solids increase affected prediction of filtration performance. Differences in strain filterability were observed with JM109 preferred over DH5 in h igh solids-containing media and RR1 preferred over JM109 in low dissol ved solids-containing media. This research demonstrates the importance of cell strain and media selection in the performance of early downst ream processing steps. (C) 1994 John Wiley and Sons, Inc.