Interspecies Streptococcal Antagonisms in Oral Biofilms

摘要 变形链球菌在龋病病因学中的作用已经得到了很好的研究。S. 变形杆菌与多达70种其他细菌一起存在于牙菌斑中。近期 研究进展表明，牙菌斑的致龋性可能是 由整个口腔细菌的联合作用决定的。这些相互作用 包括基因表达的调节、共聚集和生长抑制。我们 口腔链球菌部分通过影响毒力基因参与竞争的假设 通过直接物理相互作用和/或代谢在拮抗物种中的表达 发信号。所提出的目的是为了表征S。 变形杆菌和血链球菌，并确定口腔细菌如何影响 其他物种毒力基因(S)的表达。我们选择了变形链球菌的相互作用 和血根链霉菌是理想的模式系统，因为它们之间早就知道是相互排斥的。 来检验我们的假设，即物种间的相互作用会影响 变形链球菌和血链球菌之间的竞争，我们将： 研制基于唾液包被羟基磷灰石的双物种生物膜模型 变形链球菌和血链球菌生物被膜形成的重复性研究 寻找与变形链球菌种间相互作用有关的新基因 和血链球菌 确定变形链球菌和血链球菌毒力基因的表达谱 以回应对方 进一步描述变形链球菌和链球菌之间的直接物理相互作用。 原子力显微镜下的血吸虫

ABSTRACT The role of S. mutans in the etiology of dental caries has been well investigated. S. mutans resides in the dental plaque with up to 70 other bacterial species. Recent advances in research suggest that the cariogenic potential of dental plaque may be detemiined by the combined interactions ofthe entire oral bacteria. These interactions include modulation of gene expression, co-aggregation and growth inhibition. We hypothesize that oral streptococci compete In part by influencing virulence gene expression in the antagonistic species'by direct physical Interactions and/or metabolic signaling. The proposed Aims are designed to characterize the virulence genes of S. mutans and S. sanguinis and to identify the mechanisms how oral bacteria influence the expression of virulence gene(s) of other species. We chose the interaction of S. mutans and S. sanguinis as ideal model system because of their long known mutual exclusion. To test our hypothesis that interspecies interactions influence the outcome of the competition between S. mutans and S. sanguinis, we will: ¿ Develop a dual-species biofilm model based on saliva coated hydroxyapatite for reproducible investigation of S. mutans and S. sanguinis biofilm formation ¿ Search for new genes involved in the interspecies interaction between S. mutans and S. sanguinis ¿ Determine the expression profile of S. mutans and S. sanguinis virulence genes in response to each other ¿ Further characterize the direct physical interactions between S. mutans and S. sanguinis by atomic force microscopy