变形链球菌的适应性耐酸能力

A study of the acid adaptation of Streptococcus mutans

目的 研究变形链球菌的适应性耐酸能力及其相关生理变化。方法 通过测定在各种酸性pH值培养基中预酸化两小时后,能否使变形链球菌UA159抵抗致死性pH值的杀伤而存活及存活率,来测定适应性耐酸能力的有无及大小;氯霉素对该能力的影响可用来判断有否新蛋白的产生;用pH下降实验来测定产酸的改变。结果 变形链球菌UA159属强适应性耐酸能力类菌株,最大生存率(9.89％)出现在pH5.5预酸化组。适应性耐酸能力的产生与蛋白质的合成密切相关。酸适应能增加细菌的产酸能力。结论 在亚致死性pH值中生长能引发链球菌的某些生理变化,产生适应性耐酸能力,抵抗酸性环境的杀伤作用。

Objective To determine some characteristics of the acid adaptation of Streptococcus mutans. Methods Adaptation to acid tolerance was measured by the ability of mid - exponential - phased cell to survive a 2 ?hour exposure at a killing pH. Chloramphenicol was added into the preacidified culture in order to test whether protein synthesis was essential in acid tolerance response. pH - fall test was employed to estimate the acidogenicity. Results Prior exposure of mid -exponential phase cells to a low, sub - lethal pH would enhance survival at a pH killing unadapted cells. The greatest viability(9. 89% ) appeared when cells were preacified at pH5.5. Cells produce certain key proteins during acid tolerance response and the acidgenicity of washed cells increased. Conclusion Preacidificaton can trigger the introduction of some mechanisms to protect streptococcus from acid killing.