Inhibitory effects of sugar alcohols on acid production of dental plaque bacteria

1. 本研究的目的是通过测量酸排泄、依赖于细胞内NADH水平的荧光、糖酵解中间体和酶活性，来检验暂时暴露于空气中的链球菌细胞对细胞内葡萄糖和山梨醇代谢通量的影响。细胞暴露于空气中减少了葡萄糖和山梨醇代谢过程中的酸排泄。糖酵解中间体和荧光分析表明，暴露在空气中的葡萄糖代谢细胞的酸排泄水平降低是由于丙酮酸分解代谢的减少。在山梨糖醇存在的情况下，由于山梨糖醇-磷酸烯醇丙酮酸磷酸转移酶和山梨糖醇6-磷酸脱氢酶的底物缺乏以及丙酮酸分解代谢的减少，导致山梨糖醇-磷酸烯醇丙酮酸转移酶和山梨糖醇6-磷酸脱氢酶催化的反应速率降低。本研究的目的是通过测量酸排泄、依赖于细胞NADH和糖酵解中间体的荧光水平来检测暴露于和未暴露于空气中的变形球菌细胞在这些化合物共存时的葡萄糖和山梨醇代谢。一部分在严格厌氧条件下生长的细菌细胞（厌氧细胞）暂时暴露在空气中（好氧细胞）。当葡萄糖加入到代谢山梨醇的厌氧细胞时，酸的排泄量增加。与此同时，NADH水平下降后达到比葡萄糖代谢时更高的平台水平。好氧细胞既不代谢山梨醇，也不含细胞中间体。在山梨醇存在的情况下，加入葡萄糖2分钟后，酸的排泄开始缓慢，中间产物出现。NADH水平呈先降低后升高的趋势。这些结果表明，厌氧变形链球菌细胞同时代谢葡萄糖和山梨醇，而在山梨醇存在的情况下，好氧细胞在添加葡萄糖2 min后开始代谢葡萄糖，因为葡萄糖转运的中间体（PEP电位）已经积累。少

1. The aim of this study was to examine the effect of temporary exposure of the streptococcal cells to air on the intracellular flux of glucose and sorbitol metabolism by measuring acid excretion, fluorescence dependent on cellular level of NADH, glycolytic intermediates and enzyme activities. The exposure of cells to air decreased the acid excretions during glucose and sorbitol metabolism. The analysis of the glycolytic intermediates and the fluorescence suggested that the reduced level of acid excretion in the air-exposed glucose metabolizing cells resulted from the decrease in pyruvate catabolism. In the presence of sorbitol, the decreased acid production resulted from the reduced rates of the reactions catalyzed by sorbitol-phosphoenolpyruvate phosphotransferase and sorbitol 6-phosphate dehydrogenase because of shortage of substrates for these enzymes in addition to the decrease in pyruvate catabolism.2. The aim of this study was to examine glucose and sorbitol metabolism in Strept … More ococcus mutans cells exposed and not exposed to air at the coexistence of these compounds by measuring acid excretion, levels of fluorescence dependent on cellular NADH and glycolytic intermediates. A part of bacterial cells grown under strictly anaerobic conditions (anaerobic cells) was exposed temporarily to air (aerobic cells). When glucose was added to the anaerobic cells metabolizing sorbitol, the acid excretion was increased. At the same time, the level of NADH was decreased and then reached to the higher plateau level than that during glucose metabolism. The aerobic cells neither metabolized sorbitol nor contained cellular intermediates. At 2 min after glucose was added in the presence of sorbitol, the acid excretion was started slowly and the intermediates appeared. The level of NADH was decreased at first and then increased. These results suggested that the anaerobic S. mutans cells metabolized glucose and sorbitol simultaneously, and that in the presence of sorbitol the aerobic cells could start to metabolize glucose by addition of glucose at 2 min after glucose was added, as the intermediates (PEP potential) for the glucose transport were accumulated. Less