Figure 1.

Architecture and composition of Gram-negative and Gram-positive MVs. While MVs are heterogeneous in size and contents, typically Gram-negative MVs are encased in the outer membrane which is embedded with LPS and outer-membrane proteins, and carry periplasmic contents including peptidoglycan, enzymes and toxins, as well as cytoplasmic proteins and nucleic acids. Gram-positive MVs are comprised of the cytoplasmic membrane and have been reported to contain lipoprotein, cytoplasmic proteins, enzymes, toxins and nucleic acids.