BM53-1 Produces a Compound That Inhibits Sticky Glucan Synthesis by .

Cariogenic bacteria, such as () and , produce insoluble and sticky glucans as a biofilm material. The present study demonstrates that a lactic acid bacterium (LAB) named BM53-1 produces a substance that inhibits the sticky glucan synthesis. The BM53-1 strain was isolated from a flower of and identified as . The substance that inhibits sticky glucan synthesis does not exhibit antibacterial activity against . The cariogenic produces glucans under the control of three glucosyltransferase (GTF) enzymes, named GtfB, GtfC, and GtfD. Although GtfB and GtfC produce insoluble glucans, GtfD forms soluble glucans. Through quantitative reverse-transcriptional (qRT)-PCR analysis, it was revealed that the BM53-1-derived glucan-production inhibitor (GI) enhances the transcriptions of and genes 2- to 7-fold at the early stage of cultivation. However, that of was not enhanced in the presence of the GI, indicating that the glucan stickiness produced by was significantly weaker in the presence of the GI. Our result demonstrates that BM53-1 is useful to prevent dental caries.