Adsorption and adhesion processes in microbial growth at interfaces.

By considering bacteria as living colloidal particles it is possible to define, at least in part, the physicochemical and biological factors involved in the adhesion of bacteria to apparently inert surfaces. Adhesion is considered in terms of the attraction and repulsion forces operative as the organism approaches a substratum surface, as well as in terms of the surface free energies of the bacterium, the substratum and the liquid phase. Bacterial adhesion at a surface is preceded by molecular adsorption, a process that may alter the substratum surface properties and may provide a concentrated source of nutrients allowing limited growth of the bacteria at the surface.