ACID-BASE PHYSIOLOGY OF ORAL STREPTOCOCCI

口腔链球菌的酸碱生理学

• 批准号: 3219865
• 负责人: ROBERT E MARQUIS
• 金额: $ 12.27万
• 依托单位: UNIVERSITY OF ROCHESTER
• 依托单位国家: 美国
• 财政年份: 1983
• 资助国家: 美国
• 起止时间: 1983-03-01 至 1991-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3219865
• 关键词: Actinomyces; Enterococcus; Lactobacillus; Lactobacillus casei; Streptococcus; Streptococcus mutans; Streptococcus sanguis; acetates; acid base balance; adenosinetriphosphatase; dental plaque; electrical potential; fatty acid transport; glucose transport; glycolysis; hydrogen transport; hydroxyapatites; ion transport; lactates; membrane permeability; microorganism culture; minerals; oral bacteria; radioassay; topical fluoride therapy

The proposed project is a continuation of ongoing work on the physiology of acidurance of dental bacteria. Acidurance is one of the cardinal cariogenic properties of plaque bacteria. The most aciduric plaque bacteria, notably Streptococcus mutans and Lactobacillus organisms, are also the most cariogenic and can reduce the pH value of plaque to slightly below 4.0 so that teeth are subjected to severe acid attack and resulting lesions, which are difficult to remineralize. The acidurance of plaque streptococci was found not to depend mainly in inherent acid resistances of cytoplasmic enzymes but rather on the membrane functions of proton extrusion out of the cell and proton exclusion by membrane lipoidal barriers. Agents which upset proton currents across the membrane greatly reduce acidurance, especially of S. mutans. The proposed project is expanded to consider other cariogenic bacteria - L. casei because of the view that it is active at the leading edge of cariogenic plaque where other bacteria may be inhibited by fluoride or acid, and Actinomyces viscosus because of its involvement in root-surface caries. Work will continue with S. mutans and S. sanguis. A primary consideration will be of changes in acidurance of whole cells due to changes in DeltapH and Deltapsi across the cell membrane, in environmental levels of calcium, magnesium, sodium, potassium, weak acids, including bicarbonate, and in oxidation-reduction potential. This work will be coupled to assessments of proton permeabilities of the cells and functioning of membrane ATPases in isolated membranes, permeabilized cells or vesicles. There will be a focus on the biochemistry and physiology of ATPases because these enzymes appear to be the major engines of acidurance. However, other mechanisms for proton export, including metabolic acid extrusion, will be assessed. The capacities of cariogenic bacteria to adapt to acid enviornments will be explored by use of continuous culture and physiologic characterization. Finally, we shall determine the bases for acid inhibition of glycolysis and growth with focus on acid sensitivities of transport reactions. The ultimate aim of the work is to find means to reduce acidurance through chemical agents or use of implantable, less aciduric organisms which still can compete with other plaque bacteria.

拟议的项目是继续进行有关生理学的持续工作 牙科细菌的酸性。 酸性是主要的 斑块细菌的致癌特性。 最酸性斑块 细菌，尤其是链球菌突变和乳酸菌生物，是 也是最大的致癌性，可以将斑块的pH值降低到略微 低于4.0，以便牙齿受到严重的酸发作，并导致 病变，难以让人回忆。 发现斑块链球菌的酸性主要不依赖于 细胞质酶的固有酸性，而是在膜上 质子挤出的功能从细胞中排除在外，质子排除 膜型脂肪屏障。 使质子电流跨越质子电流的代理 膜大大降低了酸性，尤其是突变链球菌。 拟议的项目被扩展为考虑其他致癌细菌-L。 Casei是因为它认为它在 氟化物或 酸和放线肌粘膜，因为它参与了根表面 龋齿。 S. utans和S. sanguis将继续工作。 主要 考虑因素将是由于 在环境中，细胞膜跨膜的deltaph和deltapsi的变化 钙，镁，钠，钾，弱酸的水平，包括 碳酸氢盐和氧化还原潜力。 这项工作将是 结合对细胞的质子渗透率的评估和 在分离的膜中的膜ATPases的功能，透化细胞的功能 或囊泡。 将关注生物化学和生理学 ATPases，因为这些酶似乎是 酸性。 但是，质子出口的其他机制，包括 将评估代谢酸挤出。 致癌的能力 通过使用，将探索适应酸环境的细菌 连续文化和生理特征。 最后，我们将 确定酸抑制糖酵解和生长的基础 在转运反应的酸敏感性上。 这项工作的最终目的是找到减少通过 化学剂或使用可植入的，较少的酸性生物 可以与其他斑块细菌竞争。