Evaluation of the antibacterial and antibiofilm activity of probiotic bacteria against causative bacterial pathogens of dental caries

The most important factor in tooth decay and periodontal disease is the attachment of oral bacteria, especially streptococci, to different levels of the mouth and teeth. Therefore, by changing the microbial ecology in the mouth using probiotic producing bacteria, we can help prevent tooth decay and periodontal infections. This study aimed to evaluate the antibacterial and antibiofilm activities of probiotic producing Lactobacillus against several streptococci that cause tooth decay. Antimicrobial activity and minimal inhibitory concentration (MIC) of probiotic lactobacilli was determined by disk diffusion method and standard broth microdilution, respectively. Antibiofilm activity was assayed by a microtiter-plate screening method. The five isolates of Lactobacillus strains with probiotic properties include Lactobacillus plantarum, Lactobacillus rhamnosus, Lactobacillus reuteri, Lactobacillus fermentum, and Lactobacillus brevis were tested against Streptococcus mutans and Streptococcus sanguinis. Most of tested Lactobacillus strain at concentrations above 125 µg/mL showed antibacterial properties. Also, examination of the MICs showed that probiotic bacteria had greater effects on S. sanguinis. While, the tested probiotic bacteria did not show a significant antibiofilm effect. Our results suggest that lactobacilli with potential probiotic properties can be effective used for eliminating oral streptococcal colonization