string: Conventional TEM has shown the presence of these outer membrane derived vesicles, particularly for Pseudomonas aeruginosa (Beveridge and Graham, 1991; Beveridge, 1999), as well as for Vibrio cholerae and Neisseria meningitidis serogroup B, which have been used in the production of OMV-based vaccine development (Oster et al., 2005; Schild et al., 2008; Holst et al., 2009; Bishop et al., 2012).