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Lee S., Yeo S., Hong D., Huh C.
Graduate School of International Agricultural Technology, Seoul National University, South Korea

Dental caries are one of the most common bacterial infections in oral environment. Streptococcus mutans and Porphyromonas gingivalis are responsible for these infection diseases in mouth. Several researches indicate that S. mutans easily colonizes in mouth by biofilm formation which is the main cause of dental caries. Cariogenic property of S. mutans relies on the expression of extracellular glucosyltransferases(GTFs). Glucosyltransferases are responsible for the synthesis of insoluble glucans. Insoluble glucan biosynthesis enhances biofilm formation by increasing the attachment of S. mutans on enamel surface.
Probiotics are living microorganisms that are of benefits to the host. Lactic acid bacteria exists as a part of the microflora in the mouth. They play occasionally an opportunistic role of dental caries through their lactic acid formation and extracellular polysaccharides production. However, a recent study indicates that several lactic acid bacteria effectively inhibits cariogenic bacteria and helps oral health by preventing colonization of S. mutans. For these reasons, many industrial application of probiotics was increased to prevent dental caries.

The object of this study was to evaluate potential roles of lactic acid bacteria strain by comparing L. reuteri KCTC 3594 which had profound effects on production of reuterin and already have been used in commercial market. In vitro and in vivo activities of isolates from pig feces were evaluated by agar diffusion method, co-cultivation, calcium releasing assay and cariogenic rat model.

In this study, isolates from pig feces were evaluated by co-cultivation with S. mutans to assess inhibitory effect of isolates. L. reuteri LDTM 7503 and LDTM 7504 significantly suppressed higher bacterial growth of S. mutans than L. reuteri KCTC 3594. Also, L. reuteri LDTM 7503 and LDTM 7504 exhibited greater inhibitory activities against biofilm formation of S. mutans. Furthermore, L. reuteri LDTM 7503 and LDTM 7504 prevented better calcium degradation from hydroxyapatite than L. reuteri KCTC 3594. We evaluated in vivo activity of L. reuteri LDTM 7503 against S. mutans ATCC 25175 in cariogenic rat model. L. reuteri LDTM 7503 and LDTM 7504 showed more enhanced antibacterial activity against S. mutans than NaF administration group. These results indicated that L.reuteri LDTM 7503 has protective factors against dental caries development. These strain was identified as Lactobacillus reuteri by 16S rDNA sequencing.

In conclusion, L. reuteri LDTM 7503 and LDTM 7504 isolates from pig feces had enhanced inhibitory effects on biofilm formation and bacterial growth of S. mutans. L.reuteri LDTM 7503 was more effective in reducing viability of S. mutans and protecting rat from dental caries.

Keywords: Biofilm, Streptococcus mutans, Lactobacillus reuteri, Probiotics, Cariogenic rat model, Dental caries

Lee S., Yeo S., Hong D., Huh C. (2016). Inhibitory effect of Lactobacillus reuteri LDTM 7503 against S. mutans on rat dental caries. Conference Proceedings of IPC2016. Paper presented at the International Scientific Conference on Probiotics and Prebiotics, Budapest (p. 107.). IPC2016

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