目的

初步探讨白假丝酵母菌对变形链球菌产酸能力的影响。

方法

实验分A、B、C、D 四组，依次为白假丝酵母菌单独培养、变形链球菌单独培养、两菌混合培养、空白对照组。 在不同葡萄糖浓度（0.01 ～0.15 mol/L）或不同初始pH 值（7.0 ～4.0）下，将两菌单独或混合培养48 h 后，测定上清液pH 值，采用析因设计资料的方差分析判断两菌的产酸能力间是否存在交互作用，并以变形链球菌单独培养（B 组）为参照，评价两菌混合培养（C 组）的产酸能力。

结果

不同葡萄糖浓度下，白假丝酵母菌均可抑制变形链球菌的产酸力（P ＜0.001）。 葡萄糖浓度小于或等于0.10 mol/L时，C 组产酸量小于B 组（P ＜0.05）；葡萄糖浓度达到0.15 mol/L 时，B、C 两组的产酸量差异无统计学意义（P ＞0.05）。 pH 为7.0 ～5.5 时，白假丝酵母菌抑制变形链球菌的产酸力（P＜0.001）；pH≤5时，白假丝酵母菌对变形链球菌的产酸力无影响（P ＞0.05）。 初始pH 为7.0 时，C 组产酸量小于B 组（P ＜0.05）；初始pH 降至6.5、6.0 时，C 组与B 组差异无统计学意义（P ＞0.05）；初始pH 降至5.5 以下时，C 组的产酸量大于B 组（P ＜0.05）。 本实验条件下，混合培养的总产酸量随培养基的葡萄糖浓度升高呈增多趋势，随初始pH 降低呈减少趋势。

结论

白假丝酵母菌对变形链球菌产酸能力的影响及两菌混合培养的产酸力均与培养基葡萄糖浓度和初始pH 有关。

Objective

To explore the effect of Candida albicans （C.albicans） on the acidogenicity of Streptococcus mutans （S.mutans）.

Methods

Four groups were tested in the study as follow： C.albicans（Group A）， S.mutans （Group B）， C.albicans/S.mutans （Group C） and Group D as blank control，which were grown under different glucose concentrations （0.01 ～0.15 mol/L） and different initial pH （7.0 ～4.0）. The final pH was measured by pH meter to assess the acidogenicity after 48 hours of incubation.Factorial analysis of variance was employed to evaluate interaction effects between S.mutans and C.albicans. And the acidogenicity of C.albicans/S.mutans cocultures （Group C） was compared with that of S.mutans （Group B）.

Results

In the present study，it was demonstrated that C.albicans inhibited acidogenicity of S.mutans under different glucose concentrations （P ＜0.001）. When the concentration of glucose was below 0.10 mol/L，Group C produced less acid than Group B （P ＜0.05）. However，when the concentration of glucose increased to 0.15 mol/L，no statistical difference was observed between Group C and Group B （P ＞0.05）. Additionally， C.albicans inhibited S.mutans for the capacity of acidogenicity under mild acidic conditions （pH 7.0 ～5.5，P ＜0.001），but it had no effect under severely acidic conditions （pH ≤5， P ＞0.05）. Acid production of Group C was less than Group B at initial pH of 7.0 （P ＜0.05），but when initial pH was lower than 5.5，Group C even generated more acid than Group B （P ＜0.05）. While initial pH decreased to 6.5 or 6.0，acid production of Group C was similar to Group B （P ＞0.05）. Under the experimental conditions，total acid produced by cocultured C.albicans/S.mutans raised with the increase of glucose concentration，and declined with the decrease of initial pH of the medium.

Conclusions

Acid production of cocultured C.albicans/S.mutans and effect of C.albicans on acidogenicity of S.mutans depend on the glucose concentration and initial pH of the medium.