Potent Inhibitory Effects of D-tagatose on the Acid Production and Water-insoluble Glucan Synthesis of Streptococcus mutans GS5 in the Presence of Sucrose

We examined and compared the inhibitory effects of D-tagatose on the growth, acid production, and water-insoluble glucan synthesis of GS5, a bacterial strain of Streptococcus mutans, with those of xylitol, D-psicose, L-psicose and L-tagatose. GS5 was cultured for 12h in a medium containing 10ｵ (w/v) of xylitol, D-psicose, L-psicose, D-tagatose or L-tagatose, and the inhibitory effect of GS5 growth was assessed. Each sugar showed different inhibitory effects on GS5. Both D-tagatose and xylitol significantly inhibited the acid production and water-insoluble glucan synthesis of GS5 in the presence of 1ｵ (w/v) sucrose. However, the inhibitory effect of acid production by D-tagatose was significantly stronger than that of xylitol in presence of sucrose.