Fig. 1.

Setup of the dynamic biofilm system. The supply bottle filled with fresh LB-Sm broth is connected via silicon tubing to a 50 ml conical tube, which is fixed in a 45° angle on a metal stand. The conical tube contains a cover slip with a sterile P1000 pipette tip glued on to it. A suspension of a pIVET5n library pool is added to the conical tube and serves as reservoir for biofilm formation. By the action of a peristaltic pump, medium is pumped out of the supply bottle into the sterile P1000 pipette tip, flowing down the cover slip into the reservoir. An overflow hole at the 5 ml mark of the conical tube allows constant draining of the excess medium and keeps the reservoir volume constant. Biofilm is formed along the track of the continuous medium flow on the cover slip between the P1000 tip and the reservoir. For more details refer to section “Materials and methods”.