Faculty of Dentistry, The University of Hong Kong, Hong Kong SAR.
Faculty of Dentistry, University of Toronto, Toronto, ON, Canada.
Int Endod J. 2020 Jan;53(1):53-61. doi: 10.1111/iej.13202. Epub 2019 Aug 31.
To investigate the null hypothesis that neither the surface conditioning (collagen, serum, saliva) of hydroxyapatite (HA) discs, nor the biofilm age (3 days vs. 21 days) has a significant effect on the cellular and matrix composition of biofilms, using Enterococcus faecalis as the model organism.
Sterile HA discs were conditioned with collagen, saliva or serum, and inoculated with E. faecalis to form 3-day and 21-day-old biofilms. Unconditioned discs served as controls. The biofilms were analysed using culture-dependent and independent (confocal microscopy and biochemical analysis) methods, to determine the colony-forming units and the biofilm matrix composition (polysaccharides and proteins), respectively. Statistical analyses were performed using appropriate parametric and nonparametric tests (P = 0.05).
Collagen conditioning significantly increased the number of CFUs in the 21-day biofilms, compared to the 3-day biofilms (P < 0.05). Although the biochemical analysis revealed that surface conditioning had no significant effect on the total carbohydrate content in the 21-day biofilms, confocal microscopic analysis revealed that collagen and saliva conditioning selectively increased the polysaccharide content of 21-day biofilms, compared to the 3-day biofilms (P < 0.05).
The results of this study raise an important methodological concern that the substrate conditioning substances and biofilm age differentially influence the cellular and extracellular matrix components of E. faecalis biofilms.
研究假设羟磷灰石（HA）盘的表面条件（胶原、血清、唾液）和生物膜龄（3 天与 21 天）均不会对粪肠球菌形成的生物膜的细胞和基质组成产生显著影响。
将无菌 HA 盘用胶原、唾液或血清进行预处理，并接种粪肠球菌形成 3 天和 21 天的生物膜。未处理的圆盘作为对照。使用依赖培养和独立的（共聚焦显微镜和生化分析）方法分析生物膜，分别确定菌落形成单位和生物膜基质组成（多糖和蛋白质）。使用适当的参数和非参数检验（P=0.05）进行统计分析。
与 3 天的生物膜相比，胶原预处理显著增加了 21 天生物膜中的 CFU 数量（P<0.05）。尽管生化分析表明表面预处理对 21 天生物膜中的总碳水化合物含量没有显著影响，但共聚焦显微镜分析显示，与 3 天的生物膜相比，胶原和唾液预处理选择性地增加了 21 天生物膜中的多糖含量（P<0.05）。
本研究的结果提出了一个重要的方法学问题，即底物预处理物质和生物膜龄会对粪肠球菌生物膜的细胞和细胞外基质成分产生不同的影响。
