The aim of this project is to elucidate the microscopic mechanisms that determine the dynamic development of biofilms. For this purpose, we investigate adhesion and adsorption phenomena of selected proteins and bacteria in theory and experiment. In the theoretical part, whole proteins or bacteria are described as single particles with internal degrees of freedom. Experimentally, we characterize the structure, morphology and other properties of biofilms using atomic force microscopy/spectroscopy, ellipsometry and scattering techniques depending on parameters that influence protein and bacterial interactions and thus biofilm formation.