“…Therefore, if the OM grows faster than the underlying cell wall, the cross-linking can be missing, allowing the OM to protrude ( Figure 2B) (Wensink and Witholt, 1981). The observation that P. aeruginosa OM possesses a lower lipoprotein content than E. coli OM could explain why P. aeruginosa cells produce more OMV than E. coli (Martin et al, 1972;Mashburn-Warren and Whiteley, 2006). Mutant strains in genes encoding OM lipoproteins and proteins that are associated with the peptidoglycan layer, such as OmpA, Lpp, TolB and Pal, secrete several-fold more vesicles than their respective wild-type strains (Bernadac et al, 1998;Cascales et al, 2002;McBroom et al, 2006;Iwami et al, 2007;Song et al, 2008;Deatherage et al, 2009).…”