APPLICATION OF SUGAR ALCOHOLS COCKTAILS TO HUMAN CARIES PREVENTION

木糖醇抑制变形链球菌的糖酵解和生长。我们研究了木糖醇在牙菌斑深层的严格厌氧条件下，在不同pH值下对变形链球菌产酸的抑制作用。木糖醇抑制了葡萄糖的产酸速率，改变了酸性终产物的形态，使甲酸-乙酸占优势，细胞内果糖1,6-二磷酸水平降低，细胞内木糖醇5-磷酸（X5P）积累。这些结果在pH 5.5-7.0时显著，但在pH 5.0时不明显。pH值越高，木糖醇磷酸烯醇丙酮酸磷酸转移酶活性越高，说明木糖醇在pH值越高时能被有效地掺入，由此积累的X5P能更有效地抑制变形链球菌的糖酵解。此外，木糖醇在葡萄糖(G)、半乳糖（Gal）、麦芽糖(M)、乳糖(L)或蔗糖(5)作为能量来源的情况下，可以延缓变形链球菌的生长，但对果糖（Fr）的抑制作用很小。木糖醇对G、Gal、M、L或5型变形链球菌洗涤后的细胞产酸有抑制作用（12-83%）。变形杆菌在木糖醇存在下发酵木糖醇5-磷酸（X5P）时，通过磷酸烯醇丙酮酸-木糖醇磷酸转移酶系统（pep -木糖醇PTS）的活性在细胞内积累木糖醇5-磷酸（X5P）。然而，在Fr的存在下，没有观察到酸的产生受到抑制。此外，尽管存在pep -木糖醇PTS活性，但Fr发酵过程中X5P的量比其他糖的量要少。这些结果表明，随着XSP在细胞内的积累，木糖醇在除Fr外的各种膳食糖存在的情况下降低了变形链球菌的生长和产酸。

Xylitol inhibits the glycolysis and growth of Streptococcus mutans. We studied the inhibitory effect of xylitol on the acid production of S.mutans at several pH levels under the strictly anaerobic conditions found in the deep layer of dental plaque. Xylitol inhibited the rate of acid production from glucose and changed the profile of acidic end products to formate-acetate dominance, with a decrease in the intracellular level of fructose 1,6-bisphosphate and an intracellular accumulation of xylitol 5-phosphate (X5P). These results were notable at pH 5.5-7.0, but were not evident at pH 5.0. Since the activity of phosphoenolpyruvate phosphotransferase for xylitol was greater at higher pH, it is suggested that xylitol could be incorporated more efficiently at higher pH and that the resultant accumulation of X5P could inhibit the glycolysis of S.mutans more effectively.In addtion, xylitol retarded the growth of mutans streptococci in the presence of glucose (G), galactose (Gal), maltose (M), lactose (L) or sucrose (5) as an energy source, though the inhibition of growth on fructose (Fr) was small. Xylitol inhibited acid production by washed cells of S.mutans from G,Gal,M,L or 5 (12-83% inhibition). S.mutans accumulated xylitol 5-phosphate (X5P) intracellularly through activity of the phosphoenolpyruvate-xylitol phosphotransferase system (PEP-xylitol PTS) when they fermented these sugars in the presence of xylitol. However, in the presence of Fr, no inhibition of acid production was observed. In addition, the amounts of X5P during the fermentationof Fr were smaller than those of other sugars in spite of the presence of PEP-xylitol PTS activity. These results suggest that along with the intracellular accumulation of XSP, xylitol decreases the growth and acid production of mutans streptococci in the presence of various dietary sugars except Fr.