变异链球菌luxS基因对牙菌斑生物膜形成的影响研究

Influence of luxS of Streptococcus mutans on biofilm of dental plaque

目的敲除变异链球菌中的luxS基因,构建luxS突变株,测试变异链球菌失去luxS基因后形成牙菌斑生物膜的能力。方法把luxS基因敲除重组质粒转入变异链球菌UA159中,得到转化菌,在含有卡拉霉素的培养基中进行筛选,得到变异链球菌luxS基因突变株,并利用聚合酶链式反应(PCR)和哈氏弧菌发光实验对变异链球菌luxS突变株进行检测,通过扫描电镜,对不同时间段变异链球菌luxS突变株和变异链球菌UA159在BHIS培养液(含1%蔗糖的脑心浸液)和BHIG培养液(含1%葡萄糖的脑心浸液)中形成的生物膜进行比较。结果成功的构建了变异链球菌luxS突变株,在BHIS培养液中,变异链球菌luxS突变株形成生物膜的能力比变异链球菌UA159弱,而在BHIG培养液中,二者无显著差异。结论变异链球菌luxS基因对牙菌斑生物膜的形成有重要的影响,并且luxS基因对变异链球菌生物膜的调控是蔗糖依赖型的。

Objective To construct luxS mutant aften luxS gene of Streptococcus mutans （S.mutaus） was knocked out, and examine their ability of biofilm formation. Methods A recombinant plasmid containing the flanking fragment of luxS of S.mutans was transformed into S.mutans UA159, and selected by brain heart infusion （BHI） agar medium with kanamicin. The luxS mutant further confirmed via polymerase chain reaction （PCR） and the autoinducer-2（AI-2） bioluminescenee assay of Vibrio harveyi（V.harveyi）, and ability of luxS mutant and S.mutans UA159 biofilm formation was examined in different phases, in BHI medium with 1% sucrose and 1% glycose by scanning electron microscopy （SEM）. Results LuxS-deficient S.mutans strains were successfully constructed. Compared with S.mutans UA159, the luxS mutant maintained in BHI medium containing 1% sucrose displayed an apparent defect in biofilm formation, while they showed no significant deviation in BHI medium containing 1% glycose. Conclusion luxS gene in S.mutans can play a role in dental plaque biofilm formation, and the luxS gene is possible to regulate sucrose-dependent biofilm formation.