title: Curli fibers are required for development of biofilm architecture in Escherichia coli K-12 and enhance bacterial adherence to human uroepithelial cells.
abstract: Sessile bacteria show phenotypical, biochemical, and morphological differences from their planktonic counterparts. Curli, extracellular structures important for biofilm formation, are only produced at temperatures below 30 C in Escherichia coli K-12 strains. In this report, we show that E. coli K-12 can produce curli at 37 C when grown as a biofilm community. The curli-expressing strain formed more biofilms on polyurethane sheets than the curli-deficient strain under growth temperatures of both 25 C and 37 C. Curli are required for the formation of a three-dimensional mature biofilm, with characteristic water channels and pillars of bacteria. Observations by electron microscopy revealed the presence at the surfaces of the curli-deficient mutant in biofilm of flagella and type I pili. A wild-type curli-expressing E. coli strain significantly adhered to several lines of human uroepithelial cells, more so than an isogenic curlideficient strain. The finding that curli are expressed at 37 C in biofilm and enhance bacterial adherence to mammalian host cells suggests an important role for curli in pathogenesis.
authors.affiliation: Department of Bacteriology, Faculty of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Kikuchi
authors.forename: Yoshimitsu
authors.initials: Y
authors.lastname: Mizunoe
authors.forename: Akemi
authors.initials: A
authors.lastname: Takade
authors.forename: Seiji
authors.initials: S
authors.lastname: Naito
authors.forename: Shin-ichi
authors.initials: S
authors.lastname: Yoshida
mesh_terms: D001422:Bacterial Adhesion / Q000235:genetics / Q000502:physiology*; D018441:Biofilms / Q000254:growth & development*; D002460:Cell Line; D015169:Colony Count, Microbial; D004847:Epithelial Cells / Q000382:microbiology*; D004926:Escherichia coli / Q000472:pathogenicity* / Q000648:ultrastructure; D010861:Fimbriae, Bacterial / Q000502:physiology* / Q000648:ultrastructure; D005407:Flagella / Q000648:ultrastructure; D017353:Gene Deletion; D006801:Humans; D013696:Temperature; D037521:Virulence Factors / Q000235:genetics / Q000502:physiology
chemical_list: D037521:Virulence Factors