Lactobacillus acidophilus Membrane Vesicles as a Vehicle of Bacteriocin Delivery

Recent reports have shown that Gram-positive bacteria actively secrete spherical nanometer-sized proteoliposome membrane vesicles (MVs) into their surroundings. Though MVs are implicated in a broad range of biological functions, few studies have been conducted to examine their potential as delivery vehicles of antimicrobials. Here, we investigate the natural ability of <i>Lactobacillus acidophilus</i> MVs to carry and deliver bacteriocin peptides to the opportunistic pathogen, <i>Lactobacillus delbrueckii</i>. We demonstrate that upon treatment with lactacin B-inducing peptide, the proteome of the secreted MVs is enriched in putative bacteriocins encoded by the <i>lab</i> operon. Further, we show that purified MVs inhibit growth and compromise membrane integrity in <i>L. delbrueckii</i>, which is confirmed by confocal microscopy imaging and spectrophotometry. These results show that <i>L. acidophilus</i> MVs serve as conduits for antimicrobials to competing cells in the environment, suggesting a potential role for MVs in complex communities such as the gut microbiome. With the potential for controlling their payload through microbial engineering, MVs produced by <i>L. acidophilus</i> may be an interesting platform for effecting change in complex microbial communities or aiding in the development of new biomedical therapeutics.