2.2. Twitch Motility Assays

Cells were stab-inoculated with a toothpick through a thin (∼3 mm) 1% LB agar layer on the bottom of a Petri dish. After incubation for 24−48 h at 30°C, a hazy zone of growth was observed at the interface between the agar and the polystyrene surface. The ability of bacteria to twitch strongly on the polystyrene surface was examined by removing the agar, eliminating unattached cells with a stream of tap water, and staining attached cells with a 1% (w/v) crystal violet solution [16]. Each assay was performed in triplicate and repeated three times.