The Pseudomonas aeruginosa strain (PAO1, ATCC BAA-47) was used for all the experiments. For each experiment, an aliquot of bacteria was grown overnight at 37 °C in TSB with shaking at 225 rpm to achieve a stationary phase suspension. Afterwards, an aliquot was diluted 1:5 into fresh TSB and incubated at 37 °C for additional 2 h at 37 °C to reach an exponential growth phase. Bacterial cells were harvested by centrifugation at 1,500 × g for 10 min, washed twice and resuspended in PBS to adjust the concentration at 6 × 107 CFU/ml, for use in the experiments.