Biofilms are considered the predominant lifestyle form of bacteria, can be found in all sorts of environments, confer numerous advantages to bacteria and allow them to live as a community. They are often linked to disease and as such most research focus has been towards the elimination of bacterial biofilms. I am interested, however, in the biofilms that are produced by gut symbionts. In particular, my aim is to reveal which members of a defined microbial community are essential for biofilm formation and how they interact with each other.