Antibacterial and anti-biofilm effects of postbiotic mediator derived from Jeotgal isolate Lactiplantibacillus plantarum KMC12 against Streptococcus mutans

Background Dental caries, commonly known as tooth decay, is a progressive breakdown of tooth tissues caused by the biofilm-producing bacteria, Streptococcus mutans. S. mutans plays a primary role in the initiation and progression of dental caries by producing a biofilm called dental plaque.Aim This study aimed to evaluate the antibacterial and anti-biofilm effects of the neutralized postbiotic mediator (nPM) derived from Lactiplantibacillus plantarum KMC12 and to assess its potential as a therapeutic agent against S. mutans.Methods KMC12 nPM was prepared through centrifugation, filtration and lyophilization. Its antibacterial and anti-biofilm effects were investigated through MIC/MBC assays, membrane permeability tests, biofilm formation quantification, EPS production measurement, RT-qPCR analysis of biofilm-related genes, and cytotoxicity assays using Caco-2 cells.Results KMC12 nPM exhibited antibacterial activity with MIC and MBC values of 128 and 256 mg/mL, respectively, and caused approximately 87% membrane damage at 512 mg/mL. Biofilm formation was inhibited by 36% at 256 mg/mL and 83% at 512 mg/mL. Furthermore, KMC12 nPM significantly downregulated gtfB, gtfD, ftf, aguD and atpD gene expression and reduced EPS production without showing cytotoxicity.Conclusion These results suggest KMC12 nPM as a promising, novel therapeutic agent for inhibiting S. mutans biofilm formation and caries prevention.