The matrix of Pseudomonas aeruginosa biofilms

描述(申请人提供)：铜绿假单胞菌致病的一个关键因素是在囊性纤维化(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)，稳定生物膜并充当支架。藻酸盐一直被认为是EPS生物膜基质的主要多糖。然而，最近的研究表明，藻酸盐不参与非粘液型铜绿假单胞菌生物被膜的形成，这些非粘液型铜绿假单胞菌是最早定植于CF患者的，也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最初定植后数月或数年。在铜绿假单胞菌转化为藻酸盐产生表型之前，人们对铜绿假单胞菌如何在恶劣的、富含炎症的肺环境中生存的理解上仍然存在很大的差距。需要检验的中心假设是，铜绿假单胞菌具有表达替代EPS分子的能力，这些EPS分子对于感染期间铜绿假单胞菌生物膜的形成和持久性是必不可少的。这一应用将集中在一种可替代的多糖，命名为PSL，它在生物膜的形成中起着关键作用。总体目标是确定PSL在生物被膜发育、结构、抗菌剂耐药性和铜绿假单胞菌致病机制中的作用。目标1将集中于确定psi基因簇中生物膜形成所需的基因，并了解PSL在生物膜基质形成中的作用。在第二个目标中，将研究PSL基因簇的调控，并验证PSL基因在生物膜发育过程中受到空间和时间控制的假设。最后，目标3中的实验将确定PSL是否有助于生物膜的持久表型，从而在铜绿假单胞菌毒力中起重要作用。进一步了解这种关键的生物被膜成分将导致旨在抑制生物被膜形成的策略，而生物被膜形成是铜绿假单胞菌发病的一个关键方面。

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.