application of prebiotics and probiotics to improve oral and dental health by inhibiting <i>streptococcus mutans</i>

Background: the most common method to combat microorganisms that cause tooth decay is the use of antibiotics. however, despite the benefits of antibiotics, their use has significant disadvantages, such as the increased resistance of microorganisms to these chemicals. objectives: a promising and safer alternative is the use of probiotics and prebiotics, which can reduce or inhibit the growth of disease-causing oral microorganisms. streptococcus salivarius is one such probiotic, while inulin and nisin are the prebiotics commonly recommended for this purpose. methods: several assays, including agar bilayer interference, agar well penetration, and microdilution, were used to assess the antibacterial activities of s. salivarius k12 and s. salivarius m18 probiotics, as well as those of the prebiotics nisin and inulin. additionally, bile salt and low ph tolerance assessments were conducted for the probiotics, and the synthesis of bacteriocins by the probiotics was verified using proteolytic and enzymatic activity assays. results: the minimum inhibitory concentration (mic) assay revealed that s. mutans growth was inhibited by s. salivarius k12 and s. salivarius m18 at a concentration of 75%, and by nisin and inulin at 200 iu/ml. in the well penetration assay, s. salivarius k12 exhibited significantly better results compared to s. salivarius m18. nisin had significantly greater inhibitory effects on s. mutans compared to inulin. a combination of all four components (s. salivarius k12, s. salivarius m18, nisin, and inulin) resulted in maximum antibacterial activity, indicating a synergistic effect. based on the agar bilayer assay and the growth inhibition zone diameters, nisin showed the highest antibacterial activity against s. mutans, followed by s. salivarius k12, inulin, and s. salivarius m18. enzymatic digestion and proteolytic activity assays confirmed the synthesis of bacteriocins by s. salivarius k12 and s. salivarius m18. both probiotics demonstrated bile salt tolerance at a concentration of 0.3% and surviving rates of 36% and 33%, respectively, at ph 2. conclusions: the most important finding of the current study is the synergistic effect between the highlighted prebiotics and probiotics, which may offer a novel and effective combination for preventing tooth decay.