Investigation of antimicrobial effect of postbiotics derived from Bifidobacterium lactis (Bb12) on Streptococcus mutans and determination of physicochemical, rheological and sensory properties of chewing gum containing the mentioned postbiotics

Abstract

Abstract Introduction and purpose: Dental caries is one of the most common infectious diseases worldwide. The occurrence of this disease depends on various causes, including habits and diet, as well as bacterial infection. Streptococcus mutans is the main caries-causing bacteria. As bacterial resistance to conventional drugs and antibiotics increases, there is always a need to search for new antibacterial agents. Recently, probiotics have been one of the options to control the growth of oral S. mutans, and several studies have been conducted in this field and confirmed their favorable effect. Part of the antibacterial effect of probiotics is related to the metabolites they produce. Therefore, considering some clinical concerns and industrial challenges that probiotics have due to their living nature, postbiotics can be regarded as an alternative due to their non-living nature, antibacterial agents, safety, and stability. Therefore, in the present study, while investigating the antibacterial effects of postbiotics derived from Bifidobacterium animalis subsp. lactis BB-12 against S. mutans, in addition to surveying its safety, the mentioned postbiotics were added to the chewing gum formulation, and the rheological, sensory, and physicochemical characteristics of the resulting product were investigated. Materials and methods: In this study, to investigate the antibacterial properties of the postbiotic (supernatant) against the caries-causing bacteria S. mutans, agar well diffusion, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC) tests were applied. Then, using the crystal violet method, the effect of postbiotics on the reduction of biofilm formation (adhesion) and preformed biofilm by S. mutans bacteria was investigated. Postbiotic immunity and its possible cytotoxicity were also measured using the MTT method on the HGF1 cell line. Finally, after the initial tests, the postbiotic powder was added to the chewing gum formulation, and the sensory, texture, and moisture characteristics of the produced postbiotic chewing gum were evaluated. Results: The results showed that the MIC of the growth of S. mutans and also the minimum bactericidal concentration are 6.25 and 12.5 mg/ml, respectively. The concentration of 6.25 mg/ml and higher concentrations significantly (p ≤ 0/01) reduced biofilm adhesion, but none of the concentrations caused the reduction of the preformed biofilm. In the MTT test, the value of IC50 after 24 hours of treatment of cells with postbiotic was determined to be 12.5 mg/ml. The addition of postbiotics to the gum formulation generally did not cause significant changes in the sensory and texture characteristics of the gum. However, tissue cohesiveness and adhesiveness as well as overall acceptance during texture analysis and sensory evaluation of postbiotic chewing gum were significantly (p ≤ 0/029) higher than the control one (without postbiotic) respectively. Conclusion: It seems that the use of postbiotics instead of probiotics has a similar effect and can be effective in the prevention and treatment of many oral and dental infectious diseases caused by pathogens such as S. mutans, and the results of the present study confirm this. However, this study is only a laboratory study during which the antibacterial, anti-adhesion, cytotoxicity, and applicability effects of postbiotics in chewing gum formulation were examed and confirmed. To prove the preventive and therapeutic effects more precisely, human clinical studies should be conducted to determine their effectiveness and the appropriate dosage for food and medicinal use. Keywords: probiotic, postbiotic, functional food, dental decay, oral health, chewing gum