Interspecies Streptococcal Antagonisms in Oral Biofilms

摘要 S的作用。变形菌在龋齿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。最近 研究的进展表明，牙菌斑的致龋潜力可能是 由整个口腔细菌的相互作用决定。这些相互作用 包括基因表达调节、共聚集和生长抑制。我们 假设口腔链球菌竞争部分是通过影响毒力基因 通过直接的物理相互作用和/或代谢作用在拮抗物种中表达 发信号。本研究的目的是研究沙门氏菌的毒力基因。 mutans和S.血，并确定口腔细菌如何影响 其他物种毒力基因的表达。我们选择了S.变形 和S.血统是理想的模型系统，因为它们长期以来相互排斥。 为了验证我们的假设，即物种间的相互作用会影响 竞争S。变异链球菌和S. sanguinis，我们将： 开发基于唾液涂层羟基磷灰石的双物种生物膜模型， S. mutans和S.血生物膜形成 寻找与S.变形 和S.血统主义 确定S.变异链球菌和S.血吸虫毒力基因 相互响应 进一步表征S之间的直接物理相互作用。mutans和S. 用原子力显微镜观察血细胞

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