Bacteriophage infection produces membrane vesicles in Escherichia coli via both explosive cell lysis and membrane blebbing

Membrane Vesicles (MVs) are membrane-bound spherical nanostructures that prevail in all three domains of life. In Gram-negative bacteria, MVs are thought to be produced through blebbing of the outer membrane and are often referred to as outer membrane vesicles (OMVs). We have recently described another mechanism of MV biogenesis in Pseudomonas aeruginosa that involves explosive cell lysis events which shatters cellular membranes into fragments that rapidly anneal into MVs. Interestingly, MVs are often observed within preparations of lytic bacteriophage, however the source of these MVs and their association with bacteriophage infection has not been explored. In this study we aimed to determine if MV biogenesis is associated with lytic bacteriophage infection. Live super-resolution microscopy demonstrated that explosive cell lysis of E. coli cells infected with either bacteriophage T4 or T7, produced MVs derived from shattered membrane fragments. Infection by either bacteriophage was also associated with the formation of membrane blebs on intact bacteria. TEM revealed multiple classes of MVs within phage lysates, consistent with multiple mechanisms of MV biogenesis. These findings suggest that bacteriophage infection may be a major contributor to the abundance of bacterial MVs in nature.