Stationary Phase Behavior in Oral Streptococci

描述：变形链球菌是龋齿的主要病原体。我们认为，静止期细菌对变形链球菌在牙菌斑生物膜中的行为和存活至关重要，因此对其在龋齿中的作用至关重要。它们无疑是变形链球菌不吃不吃的生活方式的关键部分，因为饥荒会导致进入静止阶段。然而，大多数关于变形链球菌的研究都是关于呈指数增长的细菌。我们建议验证生物膜中静止期细菌的行为与营养细菌不同的一般假设，并在决定成熟生物膜的特性，特别是其持久性方面发挥重要作用。我们建议使用在流式细胞中形成的单物种生物膜来验证这一假设。我们建议测试静止相细菌在生物膜中长时间的碳源饥饿中存活的情况，以及它们对营养恢复和酸休克的反应。我们将测试不同处理对细菌从固定相生物膜脱落的影响，并测试脱落细菌在第二流细胞中启动二次生物膜形成的有效程度。我们建议使用荧光蛋白GFPmut3b*作为探针来定位表达已知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性质的差异。我们将筛选新的静止期表达基因。这些基因将有助于测试是否存在不同类型的具有不同抗性和对营养物的不同反应的静止期细菌。它们将给出在固定阶段表达的各种函数的指示。我们建议测试这些基因的作用。我们建议鉴定和表征固定相基因表达的调节因子。这些研究将有助于更好地理解变形链球菌在成熟牙菌斑生物膜中如何持续存在并对环境波动做出反应。

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.