Characterization of the Outer Membrane Vesicles of Pseudomonas aeruginosa Exhibiting Growth Inhibition against Acinetobacter baumannii

We investigated the Pseudomonas aeruginosa (PA) outer membrane vesicles (OMVs) and their effect on Acinetobacter baumannii (AB) growth in vitro. The inhibitory effects of PA on AB were assessed using a cross-streak assay. The OMVs were extracted through high-speed centrifugation, tangential flow filtration, and ultracentrifugation and characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), transmission electron microscopy (TEM), and nanoparticle tracking assays (NTAs). Proteomic analysis was conducted to compare the OMVs of different PA strains. PA022 exhibited more pronounced inhibition of AB growth compared with PA ATCC 27853. TEM confirmed the presence of OMVs in both PA022 and PA ATCC 27853, revealing phospholipid bilayer structures. The NTA revealed similar sizes and concentrations. Proteomic analysis identified 623 and 538 proteins in PA022 and PA ATCC 27853 OMVs, respectively, with significant proportions of the outer membrane and extracellular proteins, respectively. Importantly, PA022 OMVs contained six known virulence factors and motility-associated proteins. This study revealed the unique characteristics of PA OMVs and their inhibitory effects on AB growth, shedding light on their role in bacterial interactions. Proteomic analysis provides valuable insights into potential pathogenic functions and therapeutic applications against bacterial infections.