Poster Presentation Lorne Infection and Immunity 2022

The mechanisms of P. aeruginosa OMV biogenesis may alter their cargo composition and subsequent biological functions. (#229)

Lauren Zavan 1 2 , Cynthia Whitchurch 3 , David Greening 4 , Maria Kaparakis Liaskos 1 2
  1. Department of Physiology, Anatomy and Microbiology, La Trobe University, Bundoora, Victoria, Australia
  2. Research Centre for Extracellular Vesicles, La Trobe University, Bundoora, Victoria, Australia
  3. Quadram Institute Bioscience, Norwich Research Park, NR4 7UQ, Norwich, UK
  4. Baker Heart and Diabetes Institute, Melbourne, Australia

Outer membrane vesicles are small nanoparticles produced by Gram­‑negative bacteria as part of their natural growth. There are currently two well understood mechanisms of OMV biogenesis, the budding of OMVs from the cell membrane during normal bacterial growth and the formation of OMVs during endolysin mediated explosive cell lysis. OMVs are released by bacteria to contribute to bacterial functions and can play a role in bacterial communication and survival. Specifically, OMVs can package antimicrobial compounds to be delivered to competing bacteria. However, it is currently unknown whether the mechanism of biogenesis can determine the packaging of cargo into OMVs and their biological functions. Therefore, in this study we examined whether the production of OMVs by budding or by explosive cell lysis could determine their composition and their subsequent antimicrobial activity.  

 

OMVs were isolated from three Pseudomonas aeruginosa strains that produced OMVs either naturally, by budding only or predominately by explosive cell lysis. We compared the production and cargo composition of OMVs produced by all three P. aeruginosa strains and then determined their antimicrobial activity. We found that OMVs produced by explosive cell lysis could significantly inhibit P. aeruginosa growth whilst OMVs produced by budding could not inhibit P. aeruginosa growth. However, OMVs could significantly inhibit the growth of Staphylococcus aureus irrespective of their mechanism of biogenesis. We are currently investigating the proteome of P. aeruginosa OMVs to understand if there are any differences in the packaging of proteins into OMVs based on their mechanism of biogenesis and to specifically determine the antimicrobial compounds that are packaged into P. aeruginosa OMVs.

 

Overall, these results suggest that only P. aeruginosa OMVs produced by explosive cell lysis can inhibit the growth of their parent bacterium whilst the mechanism of OMV biogenesis does not determine their ability to inhibit S. aureus growth. Therefore, our data provides insight into how the mechanism of OMV biogenesis can regulate their cargo composition and advance our understanding of how OMV cargo dictates their subsequent biological functions.