Bacteria communicate among themselves and with other living forms in their environment via
nano-scale membrane vesicles in their
bacterial outer membranes. These vesicles are involved in
trafficking bacterial
cell signaling biochemicals, which may include
DNA,
RNA,
proteins,
endotoxins and allied
virulence molecules. This communication happens in
microbial cultures to oceans, inside animal/plant hosts and wherever bacteria may thrive.
Gram negative microorganisms deploy their
periplasm to secrete
bacterial outer membrane vesicles (OMVs) for trafficking bacterial biochemicals to target cells in their environment (Fig. 1); OMVs also carry endotoxic
lipopolysaccharide initiating disease process in their host. This mechanism imparts a variety of benefits like, long-distance delivery of bacterial secretory cargo with minimized hydrolytic degradation and extra-cellular dilution, also supplemented with other supportive molecules (e.g., virulence factors) to accomplish a specific job and yet, keeping a safe-distance from the defense arsenal of the targeted cells. Biochemical signals trafficked by OMVs may vary largely during 'war and peace' situations. In 'complacent' bacterial colonies, OMVs may be used to carry DNA to 'related' microbes for genetic transformations, and also translocate
cell signaling molecules for
quorum sensing and
biofilm formation. During 'challenge' from other cell types around, OMVs may be preferred to carry degradation and subversion enzymes. Likewise, OMVs may contain more of invasion proteins at the
host-pathogen interface (Fig. 1). It is expected, that environmental factors around the secretory microbes are responsible for inducing these bacteria to synthesize and secrete specifically-enriched OMVs, physiologically suiting the immediate task. Thus, bacterial OMVs, being strong
immunomodulators, can be manipulated for their
immunogenic contents and utilized as potent
pathogen-free
vaccines for immunizing humans and animals against threatening
infections.