The aim of this study was to evaluate the adsorption of bacteria cells on the surface of gamma-Al 2 O 3 and gamma-Al 2 O 3 /Ag (2.84wt.%) nanoparticles by means of zeta potential analysis. Our obtained results indicate that the chemical composition of water environment has a significant influence on the electrostatic interactions between sorbent and bacteria. The Ag + ions localized at the surface of Al 2 O 3 /Ag nanoparticles allowed Al 2 O 3 /Ag sorbent being less sensitive to the changes of chemical composition of water environment used for bacteria adsorption processes. In most cases, the adsorption of bacteria onto adsorbent surface changed its surface charge similar to adsorbed cells. However, by taking into consideration the sensitiveness and variability of living system such as bacteria cell, we observed that the phenomenon of adsorption (i.e. the physical interactions with sorbent surface) also changed the surface charge of bacteria cells themselves.