Abstract：
To investigate the degradation effect of bovine trypsin on multispecies biofilm of caries-related bacteria and provide an experimental foundation for the prevention of dental caries. Standard strains of S. mutans, S. sanguis, S. gordonii, and L. acidophilus were co-cultured to form 24 h, 48 h, and 72 h biofilms. The experimental groups were treated with bovine trypsin for 30 s, 1 min, and 3 min. Morphological observation and quantitative analysis of extracellular polymeric substances (EPS), live bacteria, and dead bacteria were conducted using the confocal laser scanning microscope (CLSM). The morphological changes of EPS and bacteria were also observed using a scanning electron microscope (SEM). When biofilm was treated for 1 min, the minimal inhibitory concentration (MIC) of bovine trypsin to reduce EPS was 0.5 mg/mL in 24 h and 48 h biofilms, and the MIC of bovine trypsin was 2.5 mg/mL in 72 h biofilms (P < 0.05). When biofilm was treated for 3 min, the MIC of bovine trypsin to reduce EPS was 0.25 mg/mL in 24 h and 48 h biofilms, the MIC of bovine trypsin was 1 mg/mL in 72 h biofilm (P < 0.05). The ratio of live-to-dead bacteria in the treatment group was significantly lower than blank group in 24 h, 48 h, and 72 h multispecies biofilms (P < 0.05). Bovine trypsin can destroy multispecies biofilm structure, disperse biofilm and bacteria flora, and reduce the EPS and bacterial biomass in vitro, which are positively correlated with the application time and concentration.
摘要：
探讨牛胰蛋白酶对龋齿相关菌多菌种生物膜的降解作用，为预防龋齿提供实验依据。变异链球菌的标准菌株，S.sanguis,S.Gordonii,和嗜酸乳杆菌共培养24小时，48h,和72h生物膜。实验组用牛胰蛋白酶处理30s,1分钟,和3分钟。胞外聚合物(EPS)的形态观察和定量分析,活的细菌，使用共聚焦激光扫描显微镜（CLSM）进行死亡细菌。使用扫描电子显微镜（SEM）观察了EPS和细菌的形态变化。当生物膜处理1分钟时，牛胰蛋白酶在24h和48h生物膜中降低EPS的最小抑制浓度（MIC）为0.5mg/mL，牛胰蛋白酶在72h生物膜中的MIC为2.5mg/mL(P<0.05)。当生物膜处理3分钟时，牛胰蛋白酶在24h和48h生物膜中降低EPS的MIC为0.25mg/mL，牛胰蛋白酶在72h生物膜中的MIC为1mg/mL（P<0.05）。24h内治疗组的活菌率明显低于空白组,48h,72h多物种生物膜(P<0.05)。牛胰蛋白酶可以破坏多物种生物膜结构，分散生物膜和细菌菌群，并在体外减少EPS和细菌生物量，与施用时间和浓度呈正相关。
