Biological Activity of Outer Membrane Vesicles from Clinical Isolates of Escherichia coli

Abstract

All gram‐negative bacteria secrete outer membrane vesicles (OMV) that have several functions, among them the transportation of bacterial virulence and survival factors. It has been found by other groups that certain OMV promote aberrant growth in mammalian cells upon contact. OMV provide an insoluble secretion pathway for gram‐negative bacteria and are responsible for the release of outer membrane and periplasm content out of the cell. The main objective of this investigation is to compare the composition and biological activity of OMV isolated from diverse clinical strains of E. coli. We will assess morphological effects of OMV from selected clinical isolates of E. coli on HeLa cells. Furthermore, we will also measure the lipid composition of OMV for the different strains and mutants by GC/MS. As preliminary results, we observed a significant difference in the lipid composition of the IHE3034 (pks+ strain) OMV and the IHE3034‐ΔclbP OMV. The clbP gene is presumed to be involved in the biosynthesis of colibactin. We observed that the deletion of clbP peptidase causes a decrease in the percentage of 12:0 fatty acids and an increase of 16:0 fatty acids in OMV, but not in the cellular membrane. These results begin to establish a correlation between the presence of colibactin genes and events at the bacterial cell surface.Support or Funding InformationNSF grant CHE0953254 NIH grant R25GM061838 (MBRS‐RISE program) to Ramón Gómez‐Moreno