Coupled adhesion of bacteria to surfaces

Bacterial adhesion occurs on essentially all natural, as well as man-made surfaces and poses a major concern in engineering and medicine. Controlling initial bacterial adhesion is of key importance to prevent later problems after bacteria have grown into e.g. pathogenic biofilms on biomaterials, implants and devices that poses a threat to human health. Gaining insight into initial bacterial adhesion involves the study between bacteria and a substratum surface, more specifically the bond between the two latter. This bond has previously been thought to be rigid, although recent studies have shown that it is considered viscoelastic. Modeling this bacteria-surface bond as viscoelastic offers the opportunity to determine the stiffness as well as viscosity of the bond, thereby obtaining a more clear understanding as to how the bond can be influenced and moreover prevented. Through the means of Quartz Crystal Microbalance as well as Total Internal Reflection Microscopy this thesis explores how the viscoelasticity of the bond between bacteria-surface depends on environmental conditions, like ionic strength of the surrounding fluid, substratum hydrophobicity and absence or presence of binding tethers on a bacterial cell surface.