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

1.本研究旨在通过测定酸排泄量、NADH依赖于细胞水平的荧光、糖酵解中间产物和酶活性来研究暂时暴露于空气中的链球菌对细胞内葡萄糖和山梨醇代谢的影响。细胞暴露在空气中可以减少葡萄糖和山梨醇代谢过程中的酸排泄。对糖酵解中间产物和荧光的分析表明，暴露于空气中的葡萄糖代谢细胞的排酸减少是丙酮酸分解代谢减少的结果。在山梨醇存在的情况下，产酸减少是由于山梨醇-磷酸烯醇式丙酮酸磷酸转移酶和山梨醇6-磷酸脱氢酶催化的反应速率降低所致，这是因为这些酶的底物短缺，以及丙酮酸分解代谢的减少。本研究的目的是检测Strept…中的葡萄糖和山梨醇代谢。更多的变形葡萄球菌细胞暴露在与不暴露在空气中的这些化合物共存，通过测量排酸，荧光水平取决于细胞NADH和糖酵解中间体。在严格的厌氧条件下生长的细菌细胞的一部分(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中时，其排酸增加。同时，NADH水平降低，并达到高于糖代谢的平台水平。好氧细胞既不代谢山梨醇，也不含细胞中间体。在山梨醇存在下加入葡萄糖2分钟后，开始缓慢排酸，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，变形链球菌厌氧细胞同时代谢葡萄糖和山梨醇，在山梨醇存在的情况下，好氧细胞可以在添加葡萄糖后2min通过添加葡萄糖开始代谢葡萄糖，因为葡萄糖运输的中间产物(PEP电位)积累。较少

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