Bacterial membrane vesicles (BMVs) are nanoparticles produced by all bacteria that are known to package various cargo, including protein, DNA and RNA. The main function of BMVs is to facilitate bacterial survival by sequestering antibiotics, bacteriophages and nutrients, and by mediating horizontal gene transfer. Although these functions of BMVs have been demonstrated using single bacterial species, the DNA composition and functions of BMVs produced in a mixed microbial culture remain unknown. Therefore, we aimed to characterise the DNA content of BMVs produced by a mixed culture representative of the major bacterial phyla present in the human gut, and the effect of antibiotic treatment on their BMV DNA composition.
To do this, BMVs were isolated from cultures containing 95 microbiota strains grown in the presence or absence of antibiotics and the size and cargo composition of BMVs was determined. Using next generation DNA sequencing, we identified several bacterial species within the mixed microbial culture that produced BMVs containing partial bacteriophage and prophage DNA. We isolated BMVs from these single microbiota bacterial species and identified that of these, the opportunistic pathogen Clostridium baratii produced BMVs with high levels of DNA when grown in the presence or absence of antibiotics. We are currently investigating the composition of C. baratii BMVs to examine the contribution of antibiotic treatment to altering the production, morphology and DNA packaging within these BMVs.
To date, the production and composition of BMVs from a mixed microbial community in the presence or absence of antibiotics have not been investigated. These findings will provide insights into the biogenesis of BMVs within a mixed microbial community and the effect of antibiotics on their production and composition. Ultimately, these findings will broaden our limited understanding of the contribution of BMVs to mediating bacterial evolution and evasion of antibiotics in a mixed microbial setting.