Overnight culture of Z. mobilis ZM4 and TISTR 551 (OD600 about 1.0) were inoculated 10% v/v into 30 ml of biofilm medium (contains 20 g glucose, 5 g yeast extract, 5 g (NH4)2SO4, 0.6 KH2PO4, 0.4 g Na2HPO4, 12H2O, 0.2 g MgSO4·7H2O and 0.01 g CaCl2 per liter in 10 fold dilution at pH 6.4) in which the biofilm medium in the flask contained 3 g of pretreated DEAE particles (10% w/v of resin to medium).