Adsorption of a cationic polyelectrolyte on Escherichia coli bacteria: 1. Adsorption of the polymer

Adsorption isotherms of quaternized polyvinylpyridine on the surface of Esc herichia coli bacterial cells were performed using a spectrophotometer. Res ults show that about 1 mg of polymer can adsorb per m(2) of bacterial surfa ce. Electrophoretic mobility measurements of the cells for various quantiti es of adsorbed polymer indicate that the charge of the cells can be inverte d by the cationic polyelectrolyte. Combining the adsorption isotherm and th e electrophoretic mobility measurements, we argue that the polymer chains a re adsorbed in a very flat configuration on the surface and that they form a strongly entangled network with a mesh size which decreases to a molecula r size when the quantity of adsorbed polymer increases to the plateau value of the adsorption isotherm.