Inhibitory effect of probiotic Lactobacillus supernatants from the oral cavity on Streptococcus mutans biofilms

Probiotics can release bioactive substances that can inhibit the growth and biofilm formation of pathogenic microorganisms such as Streptococcus mutans. In this context, we evaluated whether the supernatants of Lactobacillus strains isolated from caries-free subjects can inhibit S. mutans, one of the most important bacteria for dental caries. First, the supernatants of 22 Lactobacillus strains were screened for antibacterial activity against S. mutans in planktonic cultures. All 22 Lactobacillus strains studied (100%) showed antibacterial activity. Thereafter, the Lactobacillus strains with the greatest reductions in the planktonic S. mutans cultures were tested on biofilms. The L. fermentum 20.4, L. paracasei 11.6, L. paracasei 20.3 and L. paracasei 25.4 strains could significantly reduce the number of S. mutans cells in biofilms formed in hydroxyapatite (p 0.05). In addition, the supernatants of these probiotic strains could also reduce the total biomass of S. mutans biofilms (p