Fung Brittany L, Visick Karen L
Department of Microbiology and Immunology, Stritch School of Medicine Loyola University Chicago, Chicago, Illinois, USA.
J Bacteriol. 2025 Feb 20;207(2):e0047624. doi: 10.1128/jb.00476-24. Epub 2025 Jan 29.
Quorum sensing controls numerous processes ranging from the production of virulence factors to biofilm formation. Biofilms, communities of bacteria that are attached to one another and/or a surface, are common in nature, and when they form, they can produce a quorum of bacteria. One model system to study biofilms is the bacterium , which forms a biofilm that promotes the colonization of its symbiotic host. Many factors promote biofilm formation , including the symbiosis polysaccharide (SYP) and cellulose, but the role of quorum sensing is currently understudied. Recently, a quorum-sensing-dependent transcription factor, LitR, was shown to negatively influence biofilm formation in the context of a biofilm-overproducing strain. To better understand the importance of LitR, we identified conditions in which the impact of LitR on biofilm formation could be observed in an otherwise wild-type strain and then investigated its role and the roles of upstream quorum regulators in biofilm phenotypes. In static conditions, LitR and its upstream quorum regulators, including autoinducer synthases LuxS and AinS, contributed to control over biofilms that were both SYP and cellulose dependent. In shaking liquid conditions, LitR and AinS contributed to control over biofilms that were primarily cellulose dependent. LitR modestly inhibited cellulose transcription in a manner that depended on the transcription factor VpsR. These findings expand our understanding of LitR and the quorum-sensing pathway in the physiology of and illuminate negative control mechanisms that prevent robust biofilm formation by wild-type under laboratory conditions.IMPORTANCEQuorum sensing is a key regulatory mechanism that controls diverse phenotypes in numerous bacteria, including . In many microbes, quorum sensing has been shown to control biofilm formation, yet in , the link between quorum sensing and biofilm formation has been understudied. This study fills that knowledge gap by identifying roles for the quorum sensing-controlled transcription factor, LitR, and its upstream quorum-sensing regulators, including the autoinducer synthases AinS and LuxS, in inhibiting biofilm formation under specific conditions. It also determined that LitR inhibits the transcription of genes required for cellulose biosynthesis. This work thus expands our understanding of the complex control over biofilm regulation.
群体感应控制着从毒力因子产生到生物膜形成等众多过程。生物膜是细菌相互附着和/或附着于表面形成的群落，在自然界中很常见，并且在形成时会产生一定数量的细菌。一种用于研究生物膜的模型系统是[细菌名称]，它形成促进其共生宿主定殖的生物膜。许多因素促进[细菌名称]生物膜的形成，包括共生多糖（SYP）和纤维素，但群体感应的作用目前研究较少。最近，一种群体感应依赖性转录因子LitR被证明在生物膜过度产生菌株的背景下对生物膜形成有负面影响。为了更好地理解LitR的重要性，我们确定了在野生型菌株中可以观察到LitR对生物膜形成影响的条件，然后研究了它的作用以及上游群体感应调节因子在生物膜表型中的作用。在静态条件下，LitR及其上游群体感应调节因子，包括自诱导物合成酶LuxS和AinS，有助于控制既依赖SYP又依赖纤维素的生物膜。在振荡液体条件下，LitR和AinS有助于控制主要依赖纤维素的生物膜。LitR以依赖转录因子VpsR的方式适度抑制纤维素转录。这些发现扩展了我们对LitR和群体感应途径在[细菌名称]生理学中的理解，并阐明了在实验室条件下防止野生型[细菌名称]形成强大生物膜的负调控机制。
重要性
群体感应是一种关键的调控机制，控制着包括[细菌名称]在内的众多细菌的多种表型。在许多微生物中，群体感应已被证明可控制生物膜形成，但在[细菌名称]中，群体感应与生物膜形成之间的联系研究较少。本研究通过确定群体感应控制的转录因子LitR及其上游群体感应调节因子（包括自诱导物合成酶AinS和LuxS）在特定条件下抑制生物膜形成的作用，填补了这一知识空白。它还确定LitR抑制纤维素生物合成所需基因的转录。因此，这项工作扩展了我们对生物膜调控复杂控制的理解。
