Source-dependent antimicrobial activity of plant-derived lactic acid bacteria against periodontal pathogens

Periodontal disease is a prevalent inflammatory condition linked to tooth loss and systemic disorders. Plant-derived lactic acid bacteria (LAB) have emerged as promising probiotics for oral health. In this study, 80 LAB strains were isolated from tea leaves, young barley leaves, carrots, and fermented vegetables, and their antimicrobial effects against key periodontal pathogens were evaluated. Various assays, including biofilm inhibition, growth inhibition, disk diffusion, and RT-qPCR, were employed to assess activity. LAB strains from tea leaves and young barley leaves exhibited significantly stronger anti-biofilm activity and growth inhibition against Porphyromonas gingivalis than those from carrots and fermented vegetables. These strains also demonstrated notable antimicrobial activity against P. gingivalis and Fusobacterium nucleatum and significantly downregulated key virulence-related genes, including fimA, kgp, and rgpA in P. gingivalis. The results suggest that the antimicrobial efficacy of LAB is dependent on their plant source. Tea and barley-derived LAB strains may serve as potent candidates for probiotic development aimed at preventing periodontal disease. Further investigation is warranted.