Figure 2. Proposed bacterial extracellular vesicle composition and related function. Bacterial EVs are enclosed in a phospholipid bilayer originating from the bacterial membrane that along with lipo- and cytosolic proteins can be used as a nutrient source by targeted cells. Cytoplasmic proteins contained within the EV also have roles in immunomodulation and potential pharmacological applications. Lipoproteins and LPS embedded in the phospholipid bilayer moderate site-specific targeting of the EV for intra- and intercellular communication and EV constituent delivery. Nucleic acids including sRNA, mRNA, tRNA, rRNA, and DNA are transported in bacterial EVs, further contributing to immunomodulation as well as horizontal gene transfer. Recent evidence that bacterial EVs are metabolically active suggest that bacterial EV may also contain metabolites, increasing the pharmacological potential of bacterial EVs.