title: Escherichia coli biofilms have an organized and complex extracellular matrix structure.
abstract: Bacterial biofilms are ubiquitous in nature, and their resilience is derived in part from a complex extracellular matrix that can be tailored to meet environmental demands. Although common developmental stages leading to biofilm formation have been described, how the extracellular components are organized to allow three-dimensional biofilm development is not well understood. Here we show that uropathogenic Escherichia coli (UPEC) strains produce a biofilm with a highly ordered and complex extracellular matrix (ECM). We used electron microscopy (EM) techniques to image floating biofilms (pellicles) formed by UPEC. EM revealed intricately constructed substructures within the ECM that encase individual, spatially segregated bacteria with a distinctive morphology. Mutational and biochemical analyses of these biofilms confirmed curli as a major matrix component and revealed important roles for cellulose, flagella, and type 1 pili in pellicle integrity and ECM infrastructure. Collectively, the findings of this study elucidated that UPEC pellicles have a highly organized ultrastructure that varies spatially across the multicellular community.
  
  
  OBJECTIVE
  Bacteria can form biofilms in diverse niches, including abiotic surfaces, living cells, and at the air-liquid interface of liquid media. Encasing these cellular communities is a self-produced extracellular matrix (ECM) that can be composed of proteins, polysaccharides, and nucleic acids. The ECM protects biofilm bacteria from environmental insults and also makes the dissolution of biofilms very challenging. As a result, formation of biofilms within humans (during infection) or on industrial material (such as water pipes) has detrimental and costly effects. In order to combat bacterial biofilms, a better understanding of components required for biofilm formation and the ECM is required. This study defined the ECM composition and architecture of floating pellicle biofilms formed by Escherichia coli.
authors.affiliation: Center for Women's Infectious Diseases Research, Washington University School of Medicine, St. Louis, Missouri, USA.
authors.forename: Chia
authors.initials: C
authors.lastname: Hung
authors.forename: Yizhou
authors.initials: Y
authors.lastname: Zhou
authors.forename: Jerome S
authors.initials: JS
authors.lastname: Pinkner
authors.forename: Karen W
authors.initials: KW
authors.lastname: Dodson
authors.forename: Jan R
authors.initials: JR
authors.lastname: Crowley
authors.forename: John
authors.initials: J
authors.lastname: Heuser
authors.forename: Matthew R
authors.initials: MR
authors.lastname: Chapman
authors.forename: Maria
authors.initials: M
authors.lastname: Hadjifrangiskou
authors.forename: Jeffrey P
authors.initials: JP
authors.lastname: Henderson
authors.forename: Scott J
authors.initials: SJ
authors.lastname: Hultgren
mesh_terms: D018441:Biofilms; D002482:Cellulose / Q000378:metabolism; D004927:Escherichia coli Infections / Q000382:microbiology; D005109:Extracellular Matrix / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure*; D010861:Fimbriae, Bacterial / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure; D005407:Flagella / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure; D006801:Humans; D008855:Microscopy, Electron, Scanning; D056689:Uropathogenic Escherichia coli / Q000235:genetics / Q000502:physiology* / Q000648:ultrastructure
chemical_list: D002482:Cellulose
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