OMV production is substantially induced by AMPs. (A) OMVs from 0.75 μg/mL polymyxin B-treated (+) and untreated (-) WT cultures were purified, separated by SDS-PAGE, and stained using SYPRO Ruby Red. OMVs from strain ΔyieM are also shown for comparison. No significant differences in protein content could be identified across all samples. Molecular weight standards are indicated in kDa (M). (B) OMVs in the cell-free culture supernatant of antibiotic-treated WT cultures (0.75 μg/mL polymyxin B, PMB; or 0.5 μg/mL colistin, COL) were quantitated by measuring outer membrane protein and compared with the quantity of OMVs produced by untreated cultures (Untreated). Production was normalized to CFU/mL of each culture at the time of OMV preparation, and relative fold-differences are shown. (n = 9 for all experiments).