Immunofluorescence microscopy
Bacteria pellicles were gently lifted from both sides using two sterile pipette tips or a measuring micro-spatula and placed on a poly-l-lysine coated slide. The pellicle is gently washed by pipetting sterile PBS over it to remove non-adherent bacteria and left to adhere for 30mins. The slide is flooded with 3 µM DAPI (Invitrogen, D1306), 5 µg/ml wheat germ agglutinin fluorescein conjugate (WGA), (Invitrogen, W834), and 200µl Sypro ruby biofilm matrix stain (Invitrogen, F10318) in a total volume of 500µl. The slide is incubated in the dark for 30mins, gently washed with sterile water, air-dried in the dark, and imaged as described above.