Characterization of natural and gentamicin induced membrane vesicles from selected strains of Burkholderia cepacia
'Burkholderia cepacia' naturally releases membrane vesicles (n-MVs) during normal growth. Through filtration and differential centrifugation, n-MVs and gentamicin induced membrane vesicles (g-MVs) were isolated and their biological activities were compared. Putative virulence factors were found associated with these secreted n-MVs. These factors include a lipase, non-haemolytic phospholipase-C activity, and protease activity. Zymogram analysis revealed the association of 26, 28, 36, and 66 kDa peptidoglycan degrading enzymes associated with the n-MVs as well. Colloidal gold labeling was employed to follow the interaction of gentamicin with the outer membrane (OM) and resulting g-MVs from 'Pseudomonas aeruginosa' PAO1 and 'B. cepacia' C5424. In ' P. aeruginosa' PAO1 gentamicin disrupted the OM, increased g-MV production, and was packaged inside the g-MVs. Results were much different for ' B. cepacia'; gentamicin reduced the number of g-MVs and the antibiotic was only associated with their surface.