变形链球菌耐氟菌株的诱导及产酸性的实验研究

Induction of fluoride resistant mutant of S mutans and the measurement of its acidogenesis in vitro

目的 探讨变形链球菌耐氟菌株致龋毒力的变化。方法 在含有不同氟浓度的TSA上逐步诱导变形链球菌 (S mutansIngbritt)产生耐氟菌株Ingbritt FR ,用气相色谱法检测耐氟菌株的产酸量及降低pH值的能力 ,并与亲代野生菌株进行比较。结果 Ingbritt FR在体外诱导成功并稳定传代培养 ;当氟化物存在时 ,耐氟菌株的产酸量大于亲代野生株 ;无氟化物存在时 ,初始pH≥ 5 5时其产酸量小于亲代株 ,pH <5 5时则大于亲代株 ,差异有显著性。结论 变形链球菌耐氟菌株具有致龋性 ;在菌斑正常氟浓度情况下 ,其致龋力可能大于亲代野生株。

Objective To induce fluoride resistant mutant of S mutans in vitro and find out the differences of cariogenicity between them Methods Fluoride resistant strain Ingbritt FR was obtained by subculturing S mutans Ingbritt to TSA and TSB containing different concentrations of fluoride Lactic production and terminal pH of media were measured by gas chromatography method Results ①The stable fluoride resistant mutant of S mutans Ingbritt had been induced successfully in vitro; ② Lactic production of Ingbritt FR was significantly more than its parent strain at various initial pH values with 0 5 and 5 0 mmol/L fluoride whereas when no fluoride existed, there were two situations: the acid production was more than S mutans Ingbritt at initial pH above 5 0 while the result was opposite when pH was 5 0 and below Conclusion The fluoride resistant strain Ingbritt FR had a stronger cariogenic potential than its parent strain S mutans Ingbritt in physiological plaques