Fig. 1.

P. aeruginosa biofilms exposed to Gentian Violet. OPPA8 and PAO1 strains expressing green fluorescent protein were grown in flow chambers for 48 hours and subsequently exposed to 1225, 122 and 12.2 μmol/L of gentian violet for an additional 24 hours. Confocal laser microscopy was utilized to create three-dimensional reconstructions of the PA biofilms. Representative images of the three-dimensional biofilm reconstructions are shown. GV concentrations of 1225 and 122 μmol/L significantly reduced bacterial volume in OPPA8 biofilms. The lowest concentration of GV (12.2 μmol/L) demonstrated a measurable, but not statistically significant decrease in bacterial volume. Similar to OPPA8, PAO1 biofilms exposed to GV concentration at 1225 μmol/L demonstrated little to no detectable fluorescence. GV concentrations of 122 and 12.2 μmol/L were associated with a measurable, but not significant decrease in PAO1 volume. Propidium iodine staining of dead bacteria (red) was only seen in OPPA8 biofilms exposed to GV.