4.5.2. Fluorescent Labeling of Bacteria

Bacteria from overnight cultures (10 mL) were harvested by centrifugation (7000× g) for 5 min and washed once in 50 mM phosphate-buffered saline (PBS; pH 7.2). Bacterial cells were suspended in 0.5 M sodium bicarbonate buffer pH 8.0 to an OD₆₆₀ of 1.0, and 30 µL of fluorescein isothyocyanate (FITC) (10 mg/mL in 95% ethanol) were added to 10 mL of the bacterial suspensions to label cells with fluorescence as previously reported [30]. The bacterial suspensions were incubated at 37 °C in the dark with constant agitation during 60 min. FITC-labeled bacteria were harvested by centrifugation, washed three times in PBS, and suspended in the same buffer to obtain an OD₆₆₀ of 0.5.