Fig. 5: P. aeruginosa microcolonies in flow biofilms have an acidic centre.
From: Fluorescent nanosensors reveal dynamic pH gradients during biofilm formation
a The confocal 3D Z-stack image of a representative single microcolony from a P. aeruginosa biofilm grown in a BioFlux flow cell system with 5 mg mL−1 neutral charged pH-sensitive polyacrylamide nanosensors (fluorescence overlay, OG-FAM fluorescence in green, TAMRA fluorescence in red). The pH variation was observed after biofilm growth for 22 h. MatLab and ImageJ analysis of confocal images shows a lower pH of 3.5–4.0 within the core of microcolonies and a higher pH of 5.5–6.0 at the outer parts. Images represent 3D rendering of the biofilm Z-stack (b) and individual pH maps at the bottom of the biofilm (0 µm) and 5, 10, 15 and 20 µm from the bottom into the biofilm (c). Plot profiles of a straight line highlighted within the pH maps were created using ImageJ (d). Scale bars represent 10 µm.
