Figure 3

Figure 3

P. aeruginosa infections in the A549 cell line. (A) A549 cell viability. The P. aeruginosa PAO1 wild-type strain and the indicated isogenic mutant were grown in Pi-restricted (−) or Pi-sufficient (+) conditions prior to infection. Formazan production upon addition of the MTT tretazolium salt was determined spectrophotometrically at 620 nm. Uninfected cells (white bar) were used as control. (B) P. aeruginosa internalization into A549 cells. A549 cells were infected with the indicated P. aeruginosa strain previously grown in Pi-restricted conditions. Internalization is reported as the ratio between bacteria CFU inside (in) the A549 cells and CFU in the culture supernatant (out). In both panels data are means ± SD from three biological replicates (N = 3). P-values were calculated by unpaired two-tailed t-test as described in Materials and Methods and brackets indicate the comparison to which the P-value applies.