In nature, microorganisms often colonize interfaces in the form of biofilms. In medicine and engineering, this can present both risks and benefits. The in vitro reactor system of the human large intestine (peristaltic mixed tubular reactor, PETR) developed at the ibvt makes it possible, among other things, to simulate physiological conditions such as the pH gradient and water absorption of this human organ. The goal of this research focus is to use the PETR cultivation system to characterize both the interactions among the individual microorganisms of the human microbiome and the influence of infections and/or therapeutic interventions on the microbiome. Other in vitro bioreactor systems, such as a urinary catheter system, allow for the investigation of treatments for medical biofilms, using, among others, the human-pathogenic bacterium Pseudomonas aeruginosa as a model organism.