The matrix of Pseudomonas aeruginosa biofilms

描述（由申请人提供）：铜绿假单胞菌发病机制的一个关键要素是在囊性纤维化（CF）患者的肺和许多其他表面形成生物膜的能力。 生物膜内的细菌产生一种或多种胞外聚合物（EPS），其稳定生物膜并充当支架。藻酸盐被认为是生物膜EPS基质的主要多糖。然而，最近的研究表明，藻酸盐不参与非粘液样铜绿假单胞菌菌株的生物膜形成的起始，所述非粘液样铜绿假单胞菌菌株是第一个定殖于CF患者并且是大多数急性铜绿假单胞菌感染的原因。在CF患者中，粘液转化通常发生在初始定植后数月或数年。在理解铜绿假单胞菌如何在转化为产生藻酸盐的表型之前在CF肺的苛刻的、富含炎症的环境中存活方面存在显著的差距。待检验的中心假设是铜绿假单胞菌具有表达替代EPS分子的能力，所述替代EPS分子对于感染期间铜绿假单胞菌的生物膜形成和持久性是必需的。本申请将集中于一种替代多糖，命名为Psl，其在生物膜形成中起关键作用。总体目标是确定Psl在生物膜发展、结构、抗微生物剂抗性和铜绿假单胞菌发病机制中的作用。目的1将集中于定义生物膜形成所需的psi基因簇内的基因，并理解Psl在生物膜基质形成中的作用。在第二个目标中，将检查psl基因簇的调节，并测试psl基因在生物膜发育期间在空间和时间上受控制的假设。最后，目的3中的实验将确定Psl是否有助于生物膜的持久表型，并因此在铜绿假单胞菌毒力中是重要的。对这一关键生物膜组分的进一步理解将导致旨在抑制生物膜形成的策略，这是铜绿假单胞菌发病机制的关键方面。

DESCRIPTION (provided by applicant): A critical element of Pseudomonas aeruginosa pathogenesis is the ability to form biofilms in the lungs of cystic fibrosis (CF) patients and on many other surfaces. Bacteria within biofilms produce one or more extracellular polymeric substances (EPS) that stabilize the biofilm and act as a scaffold. Alginate has been considered the major polysaccharide of the biofilm EPS matrix. However, recent studies indicate that alginate is not involved in the initiation of biofilm formation by nonmucoid P. aeruginosa strains, which are the first to colonize CF patients and are the cause of most acute P. aeruginosa infections. In CF patients, mucoid conversion typically occurs months or years after initial colonization. There remain significant gaps in understanding how P. aeruginosa survives the harsh, inflammatory-rich environment of the CF lung prior to converting to the alginate-producing phenotype. The central hypothesis to be examined is that P. aeruginosa has the capacity to express alternative EPS molecules that are essential for biofilm formation and persistence of P. aeruginosa during infection. This application will focus on one alternative polysaccharide, designated Psl, which plays a critical role in biofilm formation. The overall objective is to determine the role of Psl in biofilm development, structure, resistance to antimicrobial agents, and P. aeruginosa pathogenesis. Aim 1 will focus on defining the genes within the psi gene cluster that are required for biofilm formation and understanding the role of Psl in formation of the biofilm matrix. In the second aim, the regulation of the psl gene cluster will be examined and the hypothesis that the psl genes are spatially and temporally controlled during biofilm development will be tested. Finally, experiments in aim 3 will determine if Psl contributes to the persistent phenotype of biofilms and is thus important in P. aeruginosa virulence. A further understanding of this critical biofilm component will lead to strategies aimed at inhibiting biofilm formation, which is a key aspect of P. aeruginosa pathogenesis.