Figure 2.

Biofilm formation by four Cutibacterium acnes strains in 13 × 100 mm glass tubes. Cultures were incubated for 3 days, rinsed with water, and stained with crystal violet. Strain names are indicated below. The tube at the left was incubated with sterile broth. This experiment was performed in duplicate tubes on three separate occasions with identical results. Representative tubes are shown.