Effect of surface lipopolysaccharide on the nature of membrane vesicles liberated from the Gram‐negative bacterium Pseudomonas aeruginosa

Membrane vesicles (MVs) were isolated from three isogenic lipopolysaccharide (LPS) mutants derived from the Gram-negative bacterium Pseudomonas aeruginosa PAO1 and compared with the parent strain. Parent cells possessed serotype 05 (A + B + ) LPS whereas the three mutants contained A + B - , A - B + and A - B - . The MVs from the mutants contained their expected phenotypic LPS and varied in size, especially A - B - MVs. Mass and total protein differences were also noted. When the parent and mutant cells were treated with the outer membrane-perturbing antibiotic gentamicin, all cells produced 3-5 times more MVs and these had great variation in size, mass and total protein. It is concluded that the type of cellular LPS affects both the natural and gentamicin-induced development of MVs.