变形链球菌耐氟株质子移位ATP酶活性的体外研究

Effects of Fluoride and pH on Proton translocating Membrane ATPase Activity of Fluoride resistant Streptococcus mutans in vitro

目的探讨氟化物对变形链球菌耐氟株质子移位ATP酶活性的影响,并与亲代株进行比较。方法变形链球菌耐氟株和亲代株菌液经反复冻融后,在pH值为5.0、6.0、7.0和8.0的含氟和无氟缓冲液中与ATP反应,测定反应液中无机磷含量及质子移位ATP酶活性,并进行比较。结果在pH值为5.0、6.0、7.0时,变形链球菌耐氟株和亲代株在含氟和无氟缓冲液中的质子移位ATP酶活性均不同,差异有显著性(P<0.05);pH值为5.0、6.0、7.0的含氟缓冲液中,耐氟株的质子移位ATP酶活性大于亲代株的质子移位ATP酶活性(P<0.05);pH为5.0和6.0时,耐氟株在两种缓冲液中的质子移位ATP酶活性之差与亲代株相比差异有显著性(P<0.01)。结论变形链球菌耐氟株的耐酸性比亲代株高,其致龋力大于亲代株。

OBJECTIVE To study the effects of fluoride and pH on the proton translocating membrane ATPase activity of fluoride resistant Streptococcus mutans. METHODS The cultures of fluoride resistant S. mutans and its parent strain Ingbritt were subjected to cycles of freezing and thawing and then separately resuspanded in Tris maleate buffer at desired pH and NaF level. After responding with ATP, proton translocating membrane ATPase activity of two strains were assayed. RESULTS At pH of 5.0, 6.0 and 7.0, there were significant differences in membrane ATPase activity for fluoride resistant S. mutans and the wild type strain in the presence and absence of NaF. Membrane ATPase activity of fluoride resistant strain was significantly more than that of the parent one in the presence of NaF at pH values of 5.0, 6.0 and 7.0. The difference in membrane ATPase activity of the fluoride resistant strain in the absence of NaF and in the presence of NaF was remarkably less than that of the wild type strain. CONCLUSIONS The acid tolerance of fluoride resistant S. mutans is stronger than its parent strain. The fluoride resistant strain has stronger cariogenic potential than its parent one.