Regular consumption of xylitol decreases the number of cariogenic streptococci in dental plaque. In vitro biofilm models to study the mechanism of xylitol action have been set-up, but the obtained results are contradictory. Biofilm growth is a dynamic process with time-specific characteristics that may remain undetected in conventional end-point biofilm tests. In this study we used an impedance spectroscopy instrument, xCELLigence Real Time Cell Analyzer (RTCA), that allows label-free, non-invasive real-time monitoring of biofilm formation, to explore effects of xylitol on biofilm formation by Streptococcus mutans. Based on the obtained information of biofilm dynamics, we assessed the number of viable bacteria, the polysaccharide content, and the expression levels of selected genes involved in glucan-mediated biofilm formation in different biofilm stages. Xylitol inhibition was compared with that of erythritol; another polyol suggested to have a positive impact on oral health. Our results showed that real-time monitoring provided new information of polyol-induced changes in S. mutans biofilm formation dynamics. The inhibitory effect of polyols was more pronounced in the early stages of biofilm formation but affected also the measured total amount of formed biofilm. Effects seen in the real-time biofilm assay were only partially explained by changes in CFU values and polysaccharide amounts in the biofilms. Both xylitol and erythritol inhibited real-time biofilm formation by all the nine tested S. mutans strains. Sensitivity of the strains to inhibition varied: some were more sensitive to xylitol and some to erythritol. Xylitol also modified the expression levels of gbpB, gtfB, gtfC and gtfD genes that are important in polysaccharide-mediated adherence of S. mutans. The erythritol- and xylitol- induced inhibition of biofilm formation was only partly explained by decrease in the number of viable S. mutans cells or the amount of polysaccharides in the biofilm matrix, suggesting that in addition to reduced proliferation also the matrix composition and thereby the surface attachment quality of biofilm matrix may be altered by the polyols.

中文翻译：

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木糖醇和赤藓糖醇抑制变形链球菌的实时生物膜形成。

定期食用木糖醇可减少牙菌斑中致龋链球菌的数量。建立了研究木糖醇作用机理的体外生物膜模型，但所得结果相互矛盾。生物膜生长是具有特定时间特性的动态过程，在传统的端点生物膜测试中可能无法检测到。在这项研究中，我们使用了一种阻抗谱仪xCELLigence实时细胞分析仪（RTCA），该仪器可对生物膜形成进行无标签，无创实时监测，以探索木糖醇对变形链球菌对生物膜形成的影响。根据获得的生物膜动力学信息，我们评估了活菌的数量，多糖含量，以及在不同生物膜阶段参与葡聚糖介导的生物膜形成的所选基因的表达水平。比较了木糖醇和赤藓糖醇的抑制作用；另一种多元醇建议对口腔健康产生积极影响。我们的结果表明，实时监测提供了多元醇诱导的变形链球菌生物膜形成动力学变化的新信息。在生物膜形成的早期阶段，多元醇的抑制作用更为明显，但也影响了所形成的生物膜的总量。实时生物膜测定中观察到的影响只能通过生物膜中CFU值和多糖含量的变化部分解释。木糖醇和赤藓糖醇均抑制所有九种测试的变形链球菌菌株的实时生物膜形成。菌株对抑制的敏感性各不相同：有些对木糖醇更敏感，有些对赤藓醇。木糖醇还修饰了gbpB，gtfB，gtfC和gtfD基因的表达水平，这在多糖介导的变形链球菌粘附中很重要。赤藓糖醇和木糖醇诱导的生物膜形成抑制仅部分通过减少变形链球菌活细胞的数量或生物膜基质中多糖的数量来解释，这表明除了减少增殖之外，基质组成也因此减少。多元醇可以改变生物膜基质的表面附着质量。