Figure 3.

Polymyxin B sensitivities of B. mallei WT and recombinant strains. Plate-grown organisms were suspended in PBS to a concentration of 1 × 10⁹ CFU/mL. Portions of bacterial suspensions (10⁸ CFU) were then spread onto agar plates and E strips containing a gradient of Polymyxin B concentrations (0.064–1024 ug/mL, Biomerieux) were applied onto the inoculated medium. After incubation at 37^ºC for 40 hours, minimal inhibitory concentration (MIC) values were determined by reading the intersection of the test strip with the lower part of the ellipse-shaped area of bacterial growth inhibition. (a) WT B. mallei ATCC 23344. (b) pal KO mutant carrying vector control pBHR1∆Dra. (c) pal KO mutant carrying plasmid pPal_Bm. Images are representative of 3 independent experiments. MIC values are shown at the bottom of each panel.