茴香醛对变异链球菌的抗菌活性和抗生物被膜活性

为研究茴香醛对变异链球菌的抗菌作用并阐明其抗菌机制，通过时间杀菌曲线、细胞膜完整性、细菌疏水性、生物被膜定量和RT-qPCR实验，测定茴香醛对变异链球菌的抗菌活性和抗生物被膜活性。结果表明，（1）茴香醛对变异链球菌的最小抑制浓度 (MIC)和最小杀菌浓度 (MBC)分别为4 g·L?1和8 g·L?1；（2）随着茴香醛浓度的增加，变异链球菌的核酸和蛋白质泄漏量逐渐增加；（3）激光共聚焦显微镜显示茴香醛在1×MIC的浓度下即可增加细菌细胞膜通透性破坏变异链球菌细胞膜的完整性；（4）茴香醛通过改变细菌细胞膜通透性发挥抑菌作用，通过改变变异链球菌的疏水性并下调基因表达发挥抗变异链球菌生物被膜活性。以上结果表明，茴香醛作为天然抗菌剂，具有进一步开发为抗龋齿药物的潜力。

Antimicrobial and antibiofilm activity of p-methoxybezaldehyde against Streptococcus mutans

  Objective  The present study aimed to evaluate the antibacterial effect of p-methoxybezaldehyde on Streptococcus mutans, and to clarify its probable mechanism.   Methods  Determining the antibacterial and antibiofilm activity of p-methoxybezaldehyde against Streptococcus mutans by time-kill curve, cell membrane integrity, bacterial hydrophobicity, biofilm quantification and RT-qPCR experiments.   Results  The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of p-methoxybezaldehyde against Streptococcus mutans were 4 g·L?1 and 8 g·L?1. The result showed that the contents of protein and nucleic acid gradually increased with the increase of p-methoxybezaldehyde concentration. Confocal laser scanning microscopy revealed S. mutans at 1 × MIC concentration of p-methoxybezaldehyde, resulting in changed membrane integrity in contrast to control groups.   Conclusion  The antibiofilm activity of p-methoxybezaldehyde against S. mutans was determined by the crystal violet method. p-methoxybezaldehyde exerts S. mutans antibiofilm activity by changing the hydrophobicity of S. mutans and down-regulating gene expression.These results indicate the potential of p-methoxybezaldehyde as a natural antibacterial agent to be further developed as potential anti-caries agents.