Lactobacillus acidophilus membrane vesicles demonstrate antimicrobial and antibiofilm activity against Streptococcus mutans - an in vitro and in vivo study.

Despite considerable research and various treatment approaches, dental decay remains a global health challenge. The use of synthetic antimicrobial agents can promote the development of resistance and may lead to adverse side effects. Streptococcus mutans is a key contributor to oral diseases, more so than other oral pathogens. Probiotics, however, play a beneficial role in maintaining oral health. Specifically, Lactobacillus acidophilus in the mouth can hinder harmful bacteria by competing for nutrients. Yet, evidence suggests they may also promote tooth decay. Our research focuses on membrane vesicles (MVs) isolation from L. acidophilus, and in vitro and in vivo antibacterial screening against S. mutans. The isolated MVs were consistent with previously reported vesicle size, zeta potential, and spherical morphology. They exhibit significant antimicrobial properties, prevent biofilm formation, hinder bacterial adhesion and invasion, and reduce the expression of virulence genes brpA, comDE, and spaP against S. mutans. In the in vivo model, they effectively eliminated S. mutans infection, strengthening the significance of our in vitro findings. Further proteomics study reveals the presence of possible antimicrobial peptides revealed by the DBAASP database. This study highlights the potential of MVs as a therapeutic strategy that could offer alternatives to traditional treatments and help tackle antibiotic resistance.