Abstract
Background: The most popular method against microorganisms that cause tooth decay is use of antibiotics. Despite values of antibiotics, use of these chemicals includes disadvantages such as increased antibiotic resistance of the microorganisms.
Objectives: A helpful safe alternative is the use of probiotics and prebiotics, which decrease or inhibit disease-causing oral microorganisms. Streptococcus salivarius is one of these probiotics and inulin and nisin are the prebiotics, which are recommended.
Methods: In this study, several assays such as agar bilayer interference, agar well penetration and microdilution were used to assess the antibacterial activities of Streptococcus salivarius K12 and Streptococcus salivarius M18 probiotics, as well as those of nisin and inulin prebiotics. Additionally, bile salt and low pH tolerance assessments of the probiotics and verification of bacteriocin synthesis by them were carried out using proteolytic and enzymatic activity assays.
Results: Results of the minimum inhibitory concentration assay revealed that growth of Streptococcus mutans was inhibited by Streptococcus salivarius K12 and Streptococcus salivarius M18 at a concentration of 75% and by nisin and inulin at a concentration of 200 IU/ml. Results of Streptococcus salivarius K12 was significantly better than those of Streptococcus salivarius M18 in well penetration assay. Nisin included significantly greater inhibitory effects on Streptococcus mutans, compared to that inulin did. Combination of all the four components (Streptococcus salivarius K12, Streptococcus salivarius M18, nisin and inulin) resulted in the maximum antibacterial activity, revealing their synergistic effect. Based on the results of the agar bilayer assay and growth inhibition clear zone diameters, nisin included the highest antibacterial activity against Streptococcus mutans, followed by Streptococcus salivarius K12, inulin and Streptococcus salivarius M18. Enzymatic digestion and proteolytic activity assays verified synthesis of bacteriocin by Streptococcus salivarius K12 and Streptococcus salivarius M18. These two probiotics demonstrated bile salt tolerance at a bile concentration of 0.3% as well as surviving rates of 36 and 33% at pH 2.
Conclusion: The most important finding of the current study includes synergism between the highlighted prebiotics and probiotics, which may provide a novel combination that can efficiently prevent tooth decay.
Keywords
Streptococcus salivarius Nisin Streptococcus mutans Probiotics
Copyright
© 2024, Author(s). This open-access article is available under the Creative Commons Attribution 4.0 (CC BY 4.0) International License (https://creativecommons.org/licenses/by/4.0/), which allows for unrestricted use, distribution, and reproduction in any medium, provided that the original work is properly cited.