peptidoglycan layer provides some rigidity for maintaining the bacterial cell shape, besides also protecting the microbe against challenging environments. The first step in biogenesis of gram-negative bacterial OMVs, is bulging of outer membrane above the peptidoglycan layer. Accumulation of phospholipids in the outside of the outer membrane is thought to be the basis of this outwards bulging of the outer membrane. This accumulation of phospholipids can be regulated by the VacJ/Yrb ABC transport system that transfers phospholipids from the outside of OM to the inner side. Additionally, environmental conditions as sulfur depletion can trigger a state of phospholipid overproduction that causes increased OMV release. The actual release of the vesicle from the outer membrane remains unclear. It is likely that vesicle structures can be released spontaneously. Alternatively, it has been suggested that few proteins 'rivet' the outer and cell membranes together, so that the periplasmic bulge protrudes like a 'ballooned' pocket of inflated periplasm out from the surface of the outer membrane. Lateral diffusion of 'rivet complexes' may help in pinching off large bulges of periplasm as OMVs. Bacterial membrane vesicles dispersion along the cell surface was measured in live Escherichia coli, commensal bacteria common in the human gut. Antibiotic treatment altered vesicle dynamics, vesicle-to-membrane affinity, and surface properties of the cell membranes, generally enhancing vesicle transport along the surfaces of bacterial membranes and suggesting that their motion properties could be a signature of antibiotic stress. Despite this first high-resolution, quantitative tracking of bacterial OMVs, detailed experimental work is still awaited to understand the biomechanics of OMV biogenesis and transport. OMVs are also under focus of current research in exocytosis in prokaryotes via outer membrane vesicle trafficking for intra-species, inter-species and inter-kingdom cell signaling, which is slated to change our mindset on virulence of microbes, host-pathogen interactions and inter-relationships among variety of species in earth's ecosystem. See also Exocytosis Host-pathogen interactions Host-pathogen interface List of bacterial disulfide oxidoreductases Virulence References Membrane biology Bacteriology