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Fluoride uptake by Streptococcus mutans 6715.

机译：变形链球菌6715吸收的氟化物。

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摘要

The short-term kinetics of fluoride uptake by cells from 20- to 22-h cultures of Streptococcus mutans strain 6715 were studied using rapid filtration and centrifugation techniques. Saline-suspended organisms were diluted with fluoride-containing solutions buffered at four different pH values (2.0, 4.0, 5.5, and 8.2). Fluoride disappearance from the medium was inversely related to pH and to the duration of the exposure at any given pH. The uptake was rapid and extensive at the lower pH values and decreased as the pH increased. Media fluoride concentrations subsequently increased; i.e., fluoride was released from the cells. The presence of glucose, cyanide, or iodoacetate did not influence the results. However, preincubation of the cells in fluoride-free buffers, followed by the addition of fluoride, reduced fluoride uptake markedly. Cell-to-media pH gradients were determined by the distribution of 14C-labeled 5,5-dimethyl-2,4-oxazolidinedione. Fluoride uptake was found to be a function of the magnitude of the pH gradient (P less than 0.001). It is hypothesized that fluoride uptake occurs by the diffusion of hydrogen fluoride and the subsequent trapping of ionic fluoride.
机译：使用快速过滤和离心技术研究了变形链球菌6715菌株20至22小时培养物中细胞摄取氟化物的短期动力学。用在四个不同的pH值（2.0、4.0、5.5和8.2）下缓冲的含氟化物溶液稀释盐水中悬浮的生物。培养基中氟化物的消失与pH值以及在任何给定pH值下暴露的持续时间成反比。在较低的pH值下吸收迅速而广泛，并随着pH的增加而减少。介质氟化物浓度随后增加;即，氟化物从细胞中释放出来。葡萄糖，氰化物或碘乙酸盐的存在不影响结果。但是，在无氟缓冲液中预孵育细胞，然后添加氟化物，可显着降低氟化物的吸收。通过14 C标记的5,5-二甲基-2,4-恶唑烷二酮的分布确定细胞至培养基的pH梯度。发现氟化物的吸收是pH梯度大小的函数（P小于0.001）。假设氟化物的吸收是通过氟化氢的扩散和随后的离子氟化物的捕集而发生的。

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