Loss of Sensitivity to Xylitol by Streptococcus mutans LG-1

Abstract

The effect of xylitol on the growth of Streptococcus mutans LG-1 was investigated under various conditions. Concentrations of xylitol ranging from 0.5 to 2% increased the time usually needed by the cells to reach the stationary phase in the presence of 0.2% glucose, mannose, lactose, mannitol, or sorbitol. Xylitol had no effect in the presence of fructose or sucrose. The xylitol-mediated inhibition was not modified by temperature or pH variations or by the presence or absence of oxygen. Repeated culturing in the presence of xylitol plus one of the above-mentioned sugars enabled the bacterium to tolerate the presence of xylitol. The cells, however, were still unable to grow at the expense of xylitol. The results indicate that this adaptive process arose from a mutational event.

Sucrose substitutes and their role in caries prevention

“…Possibly, the modest reduction in mutans streptococci is due to the 'fasting' effect of xylitol on oral microorganisms. The adaptation of S.mutans to xylitol has been recognised [73][74][75][76][77] , although the effect of xylitol-insensitive strains of S.mutans on fermentable carbohydrates and on glucan synthesis from sucrose has not been clarified.…”

Effects of Mouth Rinses with Xylitol and Fluoride on Dental Plaque and Saliva

“…Moreover, during food intake the glucose concentrations in plaque are higher and the pH lower, favouring transport via alternative phosphotransferase-independent transport systems [Carlsson and Hamilton, 1994]. Notably, xylitol has been shown to interfere with the metabolism of glucose [Vadeboncoeur et al, 1983], but not with the metabolism of sucrose [Mühlemann et al, 1977;Gauthier et al, 1984], which is the most abundant dietary sugar. In line with the in vivo plaque pH measurements, neither the amounts of lactate formed nor the metabolite pattern of plaque (data not shown) were altered by xylitol, which confirms previous findings [Simone et al, 1992].…”

Xylitol Inhibition of Acid Production and Growth of Mutans Streptococci in the Presence of Various Dietary Sugars under Strictly Anaerobic Conditions

“…The inhibitory effect of xylitol on the growth of and acid production by mutans streptococci in the presence of glucose has been studied by several investigators [Assev et al, 1980;Vadeboncoeur et al, 1983;Gauthier et al, 1984;Trahan et al, 1985;Beckers, 1988;Rogers and Bert, 1992], and the following mechanisms have been proposed: Xylitol is transported and phosphorylated as X5P by a PEP-xylitol PTS into S. mutans cells in the presence of glucose [Assev and Rølla, 1984;Trahan et al, 1985]. X5P inhibits the activity of glycolytic enzymes [Assev and Rølla, 1986;Trahan, 1995], resulting in the inhibition of acid production and the growth of S. mutans.…”

“…Basal culture medium (1 liter) contained 17 g of tryptone (Difco Laboratories, Detroit, Mich., USA), 3 g of yeast extract (Difco Laboratories), and 5 g of NaCl [Gauthier et al, 1984]. Ten millimolar sugar (glucose, galactose, fructose, maltose, lactose or sucrose) and 14 mM K 2 HPO 4 were added through a sterile membrane filter (pore size 0.22 Ìm, Pall Gelman Laboratory, USA) to the autoclaved basal culture medium (TYE culture medium).…”

“…In vitro experiments have shown that xylitol inhibits the growth of S. mutans in the presence of glucose [Assev et al, 1980;Gauthier et al, 1984;Trahan et al, 1985;Beckers, 1988;Rogers and Bert, 1992], and that xylitol inhibits acid production from glucose by washed cells of S. mutans [Vadeboncoeur et al, 1983;Gauthier et al, 1984;Trahan et al, 1985;Rogers and Bert, 1992]. Xylitol is converted into xylitol 5-phosphate (X5P) at the expense of phosphoenolpyruvate via the phosphoenolpyruvatexylitol phosphotransferase system (PEP-xylitol PTS) in the cells of S. mutans [Assev and Rølla, 1984;Trahan et al, 1985].…”