The impact of conditioning films on the initial adhesion of bacterial cells on polysulfone ultrafiltration membrane was investigated. Interestingly, the clean membrane possessed higher adhesion of both latex particles (CML) and Escherichia coli than the membrane conditioned with bovine serum albumin (BSA), alginate (SA), and natural organic matter (NOM). While CML and E. coli had similar zeta potentials, the motility of the E. coil increased initial adhesion on to membrane surfaces than CML. The addition of calcium ion increased the adhesion of CML and E. coli with the great impact on the SA-coated membrane as compared to BSA and NOM. (C) 2013 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.