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Research by the Group of Professor Fujiwara of the Department of Pediatric Dentistry, Graduate School of Biomedical Sciences, is Published in the July 2012 Issue of Scientific Reports

31 July 2012

The research group of Professor Taku Fujiwara of the Department of Pediatric Dentistry, Graduate School of Biomedical Sciences, Tomonori Hoshino, lecturer at this university’s hospital (Department of Pediatric Dentistry) and Professor Shigetada Kawabata of the Graduate School of Dentistry Osaka University have demonstrated the possibility that glucosyltransferase (GTF)*, one of the pathogenic factors of Streptococcus mutans causing caries, was acquired by horizontal gene transfer via transposons in lactic acid bacteria such as Lactbacillus and Leuconostoc.

Previously, only the anthropological aspects of the prevalence of caries were discussed, such as the consumption of foods containing carbohydrates, especially sugars, and the development of sugar processing technology, and the cariogenic bacterium S. mutans was regarded as already existing.
However, the results of this research suggest the possibility that with the consumption of fermented foods such as yoghurt and pickled vegetables, the genus Streptococcus encountered in the human mouth lactic acid bacteria having GTF that are contained in these foods, and as a result the genus Streptococcus acquired GTF.
Further, it was suggested that the above anthropological factors acted as selection pressures on the genus Streptococcus, and the present cariogenic bacterium S. mutans, by further horizontal gene transfer or by intra-genomic gene duplication, acquired the capacity to form a plaque biofilm which strongly adheres to the tooth surface.
Based on these results, if bacterial DNA can be collected from the teeth of the remains of a fossilized human, the gtf gene which encodes GTF in the genus Streptococcus, and the sequence can be analyzed, then a clearer understanding of the evolution of S. mutans as a cariogenic bacterium and its relation to the historical and anthropological prevalence of caries can be expected.

The results of this research have been published in the July 2012 issue of Scientific Reports.

It is posted as a featured article on the Japanese website NatureAsia.com.
http://www.natureasia.com/ja-jp/srep/abstracts/38498

* Glucosyltransferase: An enzyme which synthesizes glucan, a polymer of glucose with sugar as a substrate.
Depending on the binding mode of the glucose, it can be water-soluble or water-insoluble; S. mutans synthesizes a water-insoluble, viscous glucan which strongly adheres to the tooth surface, forming a plaque biofilm.

See the following site for more information:
http://www.nature.com/srep/2012/120718/srep00518/full/srep00518.html