Initial adhesion of microorganisms to polymeric membranes
Biofilms form in nearly every environment that provides a surface, nutrients, and water. They can be found, for example, in almost all natural aquatic environments; on teeth, bone interstices, and oral epithelia of animals and humans; on hulls of marine installations and ship bottoms; on prosthetic devices and medical implants; on water conduits and in filters; and even ion the "sterile" surfaces of the computer chip manufacturing industry. The generally accepted stages in the development of microbial biofilms are transport to the surface, initial attachment, "more permanent" adhesion, proliferation, and biofilm formation. In some of the systems described above transport is dominated by microorganism mobility (combination of thermal diffusion and motility), in others convective drag forces influence the transport of microbes toward the surface of interest. Once in close proximity to a surface, microorganisms may initially attach via any combination of intermolecular (van der Waals), electrostatic, or hydrophobic forces like simple colloids, and later become more permanently adhered by exuding extra-cellular polymeric substances (EPS).