Molecular Genetics of Biofilm Formation

描述（由申请人提供）：表面相关细菌的种群通常被称为生物膜。在大多数自然环境中，细菌主要存在于生物膜中，然而多年来对细菌生理学的研究主要集中在浮游状态。人们普遍认识到生物膜会影响无数的环境，从水管到医院病人的留置设备，这使得人们对研究这些群落形成和维持的分子机制的兴趣增加。从迄今为止描述的生物膜形成策略的多样性中出现了许多知识，使我们能够为这一现象制定一个一般假设：“生物膜的形成是一个发育过程，在这个过程中，细菌经历了从游牧的单细胞状态到久坐的多细胞状态的受调节的生活方式转换，随后的生长导致结构群落和细胞分化。”这里提出的实验代表了我们使用产孢细菌枯草芽孢杆菌对这一中心假设进行批判性测试的努力。对于活动细菌来说，从游牧到久坐的生活方式的转变通常需要停止活动，同时合成细胞外基质。虽然人们普遍认为基质的产生和运动是相互排斥的，但大多数细菌物种的生活方式转换背后的分子机制仍然是未知的。通过遗传和生化方法的结合，我们已经开始确定控制枯草芽孢杆菌从运动细胞到基质封闭的静止群落转变的分子调控电路。我们将继续应用遗传和生化方法来解决以下问题：(1)主要调节器控制生活方式开关的分子机制，(2)细胞外基质的组装，以及(3)发生在生物膜内的时空组织和细胞分化过程。

DESCRIPTION (provided by applicant): Populations of surface-associated bacteria are commonly referred to as biofilms. In most natural settings bacteria are found predominantly in biofilms, yet for many years studies of bacterial physiology focused primarily on the planktonic state. The widespread recognition that biofilms impact myriad environments, from water pipes to indwelling devices in hospital patients, has led to an increase interest in investigating the molecular mechanisms underlying the formation and maintenance of these communities. From the diversity of biofilm formation strategies thus far described emerges much knowledge that allows us to formulate a general hypothesis for this phenomenon: "Biofilm formation is a developmental process in which bacteria undergo a regulated lifestyle switch from a nomadic unicellular state to a sedentary multicellular state where subsequent growth results in structured communities and cellular differentiation." The experiments proposed here represent our efforts to critically test aspects of this central hypothesis using the sporulating bacterium, Bacillus subtilis. For motile bacteria, the lifestyle switch from a nomadic to a sedentary existence usually entails the shutdown of motility with the concomitant synthesis of the extracellular matrix. While it is generally agreed that matrix production and motility are mutually exclusive, the molecular mechanisms that underlie the lifestyle switch remain virtually unknown for most bacterial species. Through a combination of genetic and biochemical approaches, we have begun to identify the molecular regulatory circuitry that governs the transition from motile cells to matrix-enclosed sedentary communities of B. subtilis. We will continue to apply genetic and biochemical approaches to address questions regarding: (1) The molecular mechanism via which a master regulator controls the lifestyle switch, (2) The assembly of the extracellular matrix, and (3) The spatio-temporal organization and cellular differentiation processes that occur within the biofilm.