Background and Aim:Pseudomonas aeruginosa, an opportunistic human bacterial pathogen, constitutively secretes outer membrane vesicles (OMVs) into the extracellular milieu. OMVs are essential for pathogenesis of P. aeruginosa. Also OMVs are important in virulence factor secretion, bacterial survival, and biofilm formation. Therefore In this study, P. aeruginosa OMVs production was investigated from a clinical isolate of Ghaem hospital in Mashhad. Methods:OMVs were prepared as described by Siadat et al. In brief, P. aeruginosa strain was grown in LB, at 37°C for 10 h up to early stationary phase. OMVs were extracted in 0.1 M Tris-HCl, pH 8.6, 10 mM EDTA and 0.5%w/v deoxycholate. Purification of OMVs was done by sequential centrifugation at 20,000 g for 30 min followed by ultracentrifugation at 125,000 g for 2 h. The OMV pellet was homogenized in Sucrose 3%. Then physicochemical properties of extracted OMVs were analyzed by Electron microscopy, SDS-PAGE and NanoDrop. Results:The results revealed that the content of protein extracted was 0.2 mg/mL. The electron microscopy showed that OMVs were in the range of 20-200 nm in size. Also several bands were observed in SDS-PAGE analysis in which strong bands with 35-100kDA was mostly an indication for OMVs production. Conclusion:The results showed that the extracted OMVs were conformationally stable, and there were no impurity determinants in OMVs.

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