Mechanism of acid trelance of oral streptococci

口腔链球菌酸调节机制

• 批准号: 10671732
• 负责人: IWAMI Yoshimichi
• 金额: $ 1.98万
• 依托单位: TOHOKU UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1998
• 资助国家: 日本
• 起止时间: 1998 至 2000
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10671732/
• 关键词: NADH; streptococci; sugar metabolism; intracellualr pH; sorbitol; Streptococcus mutans; BCECF; 耐酸性

1. NADH-dependent fluorescence and acid excretion during glucose pulse to washed streptococcal cells were monitored simultaneously. Acid excretion started with addition of glucose. At the same time, the fluorescence dropped quickly to a minimum level and increased to a plateau level. When the acid excretion stopped, the fluorescence increased rapidly from the plateau to a maximum level. The results suggested that pyruvate metabolism started immediately after addition of glucose, then the rate of pyruvate metabolism became equal to the rate of glycolysis, and that the pyruvate metabolism stopped first when the acid excretion stopped.2. Bacterial intracellular pH (pHi) has been considered to be higher than extracellular pH (pHo) even if in the absence of energy source, such as glucose. The pHi and pHo were simultaneously measured when lactic acid was added to the S.mutans, S.sanguinis, S.salivarius cell suspensions. The pHi was measured by the BCECF method in the absence of glucose. The pHi was lower than the pHo at the range of pHo from 7.5 to 5.0 and was kept constant at pHo from 5 to 4. The pHi decreased at pHo from 4 to 3.3. It has been supposed that the rate of sorbitol metabolism in the air-exposed streptococcal cells could be limited by the inactivation of pyruvate formate-lyase by oxygen. The decreased acid production from sorbitol resulted from the reduced rates of the reactions catalyzed by sorbitol 6-phosphate dehydrogenase because of shortage of substrates for these enzymes in addition to the decrease in pyruvate catabolism. In the presence of sorbitol, the air-exposed cells could start to metabolize glucose 2 min after glucose was added, as the intermediates for the glucose transport were accumulated.

1. 同时监测nadh依赖性荧光和葡萄糖脉冲对洗涤链球菌细胞的酸排泄。酸的排泄开始于葡萄糖的添加。同时，荧光迅速下降到最低水平，然后上升到平台水平。当酸排泄停止时，荧光从高原迅速上升到最高水平。结果表明，添加葡萄糖后，丙酮酸代谢立即开始，然后丙酮酸代谢速率与糖酵解速率相等，当酸排泄停止时，丙酮酸代谢首先停止。细菌的细胞内pH值（pHi）被认为高于细胞外pH值（pHo），即使在缺乏能量来源的情况下，如葡萄糖。在变形链球菌、血链球菌、唾液链球菌的细胞悬液中加入乳酸，同时测定pHi和pHo。在不含葡萄糖的情况下，用BCECF法测定pHi。pHo在7.5 ~ 5.0范围内，pHi小于pHo， pHo在5 ~ 4范围内保持恒定。pHo下pHi由4降至3.3。据推测，暴露在空气中的链球菌细胞的山梨糖醇代谢速率可能受到氧气使丙酮酸甲酸裂解酶失活的限制。山梨糖醇产酸减少的原因是山梨糖醇6-磷酸脱氢酶催化的反应速率降低，因为这些酶缺乏底物以及丙酮酸分解代谢的减少。在山梨糖醇存在的情况下，暴露于空气中的细胞在加入葡萄糖2分钟后开始代谢葡萄糖，因为葡萄糖转运的中间体已经积累。

项目成果

H.Miyasawa: "Growth-phase- and pH-dependent xylitol inhibition on acid production of Streptococcus mutans."J Dent Res. 79(in press). (2000)

H.Miyasawa：“生长阶段和 pH 依赖性木糖醇对变形链球菌产酸的抑制。”J Dent Res。

宮澤はるみ: "Xylitolによるミュータンスレンサ球菌の酸産生阻害とそれに及ぼすpHの影響"歯科基礎誌. 42. 92-92 (2000)

Harumi Miyazawa：“木糖醇对变形链球菌产酸的抑制及其 pH 值的影响”《牙科基础杂志》42. 92-92 (2000)。

Y.Iwami: "Intracellular flux of glucose metabolism in streptococcal cells by simultaneous monitoring of NADH-dependent fluorescence and acid excretion under strictly anaerobic conditions."Oral Microbiol Immun. 14. 220-224 (1999)

Y.Iwami：“通过在严格厌氧条件下同时监测 NADH 依赖性荧光和酸排泄来了解链球菌细胞中葡萄糖代谢的细胞内通量。”口腔微生物免疫。

Y.Iwami: "Rate-limiting steps of glucose and sorbitol metabolism in Streptococcus mutans cells exposed to air."Oral Microbiology and Immunology. 15. 325-328 (2000)

Y.Iwami：“暴露于空气的变形链球菌细胞中葡萄糖和山梨醇代谢的限速步骤。”口腔微生物学和免疫学。

Y.Iwami: "Rate-limiting steps of glucose and sorbitol metabolism in Streptococcus mutans cells exposed to air."Oral Microbiol and Immunol. 15(in press). (2000)

Y.Iwami：“暴露于空气的变形链球菌细胞中葡萄糖和山梨醇代谢的限速步骤。”口腔微生物和免疫学。