Stationary Phase Behavior in Oral Streptococci

描述：变形链球菌是龋齿的主要代理人。我们认为，稳定期细菌是至关重要的行为和生存的S。变形菌在牙菌斑生物膜中的作用，因此它在龋齿中的作用。它们无疑是S的盛宴或饥荒生活方式的重要组成部分。变异，因为饥荒导致进入稳定期。然而，大多数关于S.变异体是指呈指数增长的细菌。我们建议测试的一般假设，即固定相细菌在生物膜中的行为不同于营养细菌，并在确定成熟的生物膜的属性，特别是在其持久性的重要作用。我们建议使用单种生物膜形成的流动细胞来验证这一假设。我们建议测试如何以及固定阶段的细菌生存长期的碳源饥饿的生物膜，以及它们如何响应营养恢复和酸休克。我们将测试不同处理对细菌从固定相生物膜脱落的影响，并测试脱落的细菌如何有效地在第二个流动池中启动二次生物膜形成。我们建议使用荧光蛋白GFPmut3b* 作为探针来定位表达已知的静止期特异性基因的细菌和表达植物期特异性基因的细菌。这将有助于澄清两种细菌类型之间的特性差异。我们将筛选新的稳定期表达的基因。这些基因将使测试是否有不同类型的静止期细菌具有不同的抗性和对营养的不同反应。它们将给出在稳定期所表达的函数的种类的指示。我们打算测试这些基因的作用。我们建议确定和表征稳定期基因表达的调节因子。这些研究有助于更好地理解S.成熟牙菌斑生物膜中的变形菌持续存在并对其环境的波动做出反应。

DESCRIPTION: Streptococcus mutans is the primary agent of Dental caries. We think that stationary-phase bacteria are critical to the behavior and survival of S. mutans in the Dental plaque biofilm, and hence to its role in Dental caries. They are surely a critical part of the feast-or-famine lifestyle of S. mutans, as famine causes entry into the stationary phase. Yet, most studies of S. mutans have been of exponentially growing bacteria. We propose to test the general hypothesis that stationary-phase bacteria in biofilms behave differently from vegetative bacteria and have an important role in determining the properties of mature biofilms, and in particular in their persistence. We propose using single-species biofilms formed in flow cells to test this hypothesis. We propose to test how well stationary-phase bacteria survive prolonged carbon-source starvation in biofilms and how they respond to nutrient restoration and acid shock. We will test the effect of different treatments on the shedding of bacteria from stationary-phase biofilms, and test how effectively the shed bacteria can initiate secondary biofilm formation in a second flow cell. We propose to use the fluorescing protein GFPmut3b* as a probe to locate bacteria expressing known stationary-phase-specific genes and those expressing vegetative-phase specific genes. This will help clarify the difference in properties between the two bacterial types. We will screen for new stationary-phase expressed genes. These genes will enable testing if there are different types of stationary-phase bacteria with different resistances and different responses to nutrient. They will give an indication of the sorts of function that are expressed during stationary phase. We propose to test the roles of these genes. We propose to identify and characterize the regulators of stationary phase gene expression. These studies should lead to a better understanding of how S. mutans in mature Dental plaque biofilm persists and responds to fluctuations in its environment.