胞外聚合物葡聚糖和DNA对粪肠球菌根管生物膜形成的影响

目的 研究胞外多糖和胞外DNA对粪肠球菌在人牙本质片上黏附并形成生物膜过程中的作用.方法 制备牙本质片,分成葡聚糖酶(Dextranase)组、DNA酶(DNaseI)组和对照组,体外培养获得粪肠球菌的牙本质生物膜标本.采用活菌菌落计数法、激光共聚焦扫描显微镜结合COMSTAT软件分析胞外聚合物对牙本质黏附菌量和生物膜三维结构的影响.结果 相同生物膜膜龄,Dextranase组和DNaseI组粪肠球菌牙本质黏附菌量均少于对照组,差异具有统计学意义(P＜0.05),其中1 h黏附菌量分别下降至对照组的15.61%、18.39%.激光共聚焦显微镜观察到Dextranase和DNaseI对粪肠球菌牙本质生物膜的形成有影响,处理后生物膜结构松散,生物量、底层覆盖率及平均厚度均下降,具有统计学意义(P＜0.0167),其中生物量由(3.95±0.09)μm3/μm2下降至(0.36±0.08)μm3/μm2、(1.05±0.06)μm3/μm2.DNaseI对成熟牙本质生物膜产生显著降解作用,而Dextranase对成熟牙本质生物膜作用不明显.结论 胞外多糖和胞外DNA是粪肠球菌生物膜的重要成分,对其初始黏附和生物膜三维结构起重要作用.

Effects of extracellular polysaccharide and extracellular DNA on Enterococcus faecalis biofilm formation in human root cannal

Objective To investigate the effects of extracellular polysaccharide and extracellular DNA on adhesion and biofilm formation of Enterococcus faecalis in ground sections of human dentin.Methods Ground sections of dentin were prepared and allocated to three groups: Dextranase group, DNaseI group and normal control group. Biofilm samples of Enterococcusfaecalis on dentin were obtained by culture in vitro. Colony-forming units (CFU) counts, confocal laser scanning microscope (CLSM) and COMSTAT software were used to measure the effect of extracellular polysaccharide on the bacterial adherence to dentin and the three dimensional structure of biofilm. Results Given a certain age of biofilm, less bacterial adherence of Enterococcus faecalis to dentin was found in both Dextranase and DNaseI group than that in normal control group (P＜0.05). The 1-h bacterial adherence in these two groups was 15.61% and 18.39% less, respectively, as compared with the normal control group. CLSM showed that treatment with Dextranase or DNaseI may affected dentin biofilm formation: loosened biofilm structure and reduction in biomass, bottom coverage and mean thickness (P＜0.0167). Notably, the biomass in Dextranase and DNaseI group decreased significantly from ( 3.95 ± 0.09 ) μm3/μm2 to (0.36 ± 0.08 ) μm3/μm2 and ( 1.05 ± 0.06 ) μm3/μm2, respectively.DNaseI but not Dextranase was shown to degrade the mature biofilms on dentin. Conclusion Extracellular polysaccharide and extracellular DNA may be important components of Enterococcus faecalis bioflim structure, which contribute significantly to initial bacterial adhesion and three dimensional biofilm structure.