Bacterial extracellular vesicles as cell-cell communication mediators

Extracellular vesicles constitute a heterogeneous group of nanoparticles, released by both prokaryotic and eukaryotic cells, which perform various biological functions and participate in cell-cell communication. Bacterial extracellular vesicles are made of lipids, proteins and nucleic acids. There are a number of hypotheses for the formation of extracellular vesicles, but the mechanisms of biogenesis of these structures remain unclear. Hardly soluble metabolites or signaling molecules, DNA and RNA are vesicles cargo. Extracellular vesicles have a protective function, they can eliminate other bacterial cells and participate in horizontal gene transfer. The enzymes contained inside the vesicles facilitate the acquisition of nutrients and help colonize various ecological niches. Signal molecules carried in the vesicles enable biofilm formation. In the secreted extracellular vesicles pathogenic microorganisms carry virulence factors, including toxins, into the host cells. Via vesicles, bacteria can also modulate the host immune system. Bacterial extracellular vesicles are promising vaccine candidates and can be used as drug carriers. The review discusses the current knowledge concerning biogenesis, composition, preparation methods, physiological functions and potential applications of extracellular vesicles secreted by prokaryotic cells.