Antibacterial effect of lactic acid bacteria on the cariogenic bacterium Streptococcus mutans

Abstract

　The gram-positive facultative anaerobic bacterium Streptococcus mutans is thought to be the causative agent of caries. It is thus necessary to reduce S. mutans in the oral cavity in order to prevent caries. In this study, the growth-inhibitory effects of Lacticaseibacillus paracasei, Lacticaseibacillus casei, Levilactobacillus brevis, and Lactiplantibacillus plantarum on S. mutans were investigated in vitro. The antibacterial substance productivity of these strains was also tested. All four of the lactic acid bacteria suppressed the growth of S. mutans. The mixed culture of the four types of lactic acid bacteria and S. mutans also suppressed the growth of S. mutans. Based on the antibacterial substance productivity test, only L. paracasei and L. plantarum showed an antibacterial activity against S. mutans, suggesting that these two strains may reduce the risk of caries.