Effect of <i>bfmS</i> deletion on bacterial virulence and the ability of <i>P. aeruginosa</i> to adapt to the host.

<p>In all panels, MPAO1 and Δ<i>bfmS</i> harbor plasmid PAK1900, respectively. <b>A</b>) Photographs show lettuce midribs after three days of infection with 1×10⁷ cfu of <i>P. aeruginosa</i>. Wild-type MPAO1 strain or Δ<i>bfmS</i>/p-<i>bfmS</i> strain shows necrosis and tissue maceration of infection. The Δ<i>bfmS</i> strain shows weak signs of infection. <b>B</b>) Constitutive expression of <i>rhlR</i> in Δ<i>bfmS</i> strain could restore the virulence to the level of the wild-type MPAO1 strain. In <b>A</b>) and <b>B</b>), lettuce leaves were inoculated with 10 mM MgSO₄ as a control. <b>C</b>) Effect of <i>P. aeruginosa</i> inoculum on the survival rate of murine lung epithelial cell line 12 (MLE-12). <b>D</b>) Internalization of <i>P. aeruginosa</i> into the murine lung epithelial cell line 12 (MLE-12). In <b>C</b>) and <b>D</b>), values represent means ± SEM. <b>E</b>) Recovery of <i>P. aeruginosa</i> derivatives in a mouse model of acute pneumonia. Results are expressed as the ratio of cfu recovered per lung (output) to cfu present in the initial inoculum (input) and represent results from n = 9–10 mice per strain; the line shows the geometric mean for each group. CFU, Colony-Forming Unit. The Mann–Whitney test was used to calculate p-values (two-tailed). * p<0.05, ** p<0.01, *** p<0.001. Results are representative of two independent experiments.