蔗糖浓度对牙菌斑生物膜细菌组成及pH值影响的体外实验

摘要

Objective To investigate the effect of different concentrations of sucrose on the bacteria composition and pH of in vitro biofilm derived from dental plaque.Methods Dental plaques from five caries-active people( DMFS ＞ 3 ) were mixed and cultivated in vitro under different sucrose concentrations (0,1.5,3.0,5.0,20.0 g/L) to form biofilm,from which DNAs of bacteria were extracted and further analyzed by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE).The pH was measured and bacteria counted in the biofilm.Results As the sucrose concentration increased,the number of bacteria species decreased.Higher sucrose concentration leaded to a lower minimum pH,which was 5.4 (0 g/L),4.7( 1.5 g/L),4.5(3.0 g/L),4.2(5.0 g/L),4.2(20.0 g/L),respectively.With sucrose in culture medium,the time needed for a minimum pH in the last 12 hours was much shorter( about 6 hours) than the time needed in the first 12 hours( 10 hours).The largest number of bacteria was observed at the sucrose concentration of 5.0 g/L.Conclusions The sucrose concentration may influnce the bacteria composition of biofilm derived from dental plaque and pH.Potential acidogenic and acid-tolerant bacterial community could be screened out in the culture medium with sucrose.%目的 研究不同蔗糖质量浓度对体外牙菌斑生物膜细菌组成和pH值的影响,探讨口腔微生物在蔗糖存在下的致龋能力.方法 采集有龋者(龋失补牙面数＞3)集合牙菌斑样本5例,混合后在不同质量浓度(0、1.5、3.0、5.0及20.0g/L)蔗糖中体外培养生物膜；对生物膜进行聚合酶链反应-变性梯度凝胶电泳分析和细菌量计数,并行pH值监测.结果 随着培养基中蔗糖质量浓度增加,生物膜细菌种类减少；随着蔗糖质量浓度的升高(0、1.5、3.0、5.0、20.0g/L),生物膜培养36 h后所能达到的最低pH值呈降低趋势,分别为5.4、4.7、4.5、4.2及4.2；在有蔗糖时,最终12 h生物膜培养达到pH最小值约需6h,相比最初12h(约需10 h)明显缩短；对生物膜细菌量进行单因素方差分析结果显示,在蔗糖质量浓度为5.0g/L时细菌量最大,向下蔗糖质量浓度依次为3.0、20.0、1.5及0g/L,各组间相比差异有统计学意义(P＜0.05).结论 蔗糖浓度可影响体外牙菌斑生物膜的细菌组成和pH值,含蔗糖的培养基可筛选出具有潜在强产酸和耐酸能力的菌群.