title: Klebsiella pneumoniae yfiRNB operon affects biofilm formation, polysaccharide production and drug susceptibility.
abstract: Klebsiella pneumoniae is an opportunistic pathogen important in hospital-acquired infections, which are complicated by the rise of drug-resistant strains and the capacity of cells to adhere to surfaces and form biofilms. In this work, we carried out an analysis of the genes in the K. pneumoniae yfiRNB operon, previously implicated in biofilm formation. The results indicated that in addition to the previously reported effect on type 3 fimbriae expression, this operon also affected biofilm formation due to changes in cellulose as part of the extracellular matrix. Deletion of yfiR resulted in enhanced biofilm formation and an altered colony phenotype indicative of cellulose overproduction when grown on solid indicator media. Extraction of polysaccharides and treatment with cellulase were consistent with the presence of cellulose in biofilms. The enhanced cellulose production did not, however, correlate with virulence as assessed using a Caenorhabditis elegans assay. In addition, cells bearing mutations in genes of the yfiRNB operon varied with respect to the WT control in terms of susceptibility to the antibiotics amikacin, ciprofloxacin, imipenem and meropenem. These results indicated that the yfiRNB operon is implicated in the production of exopolysaccharides that alter cell surface characteristics and the capacity to form biofilms--a phenotype that does not necessarily correlate with properties related with survival, such as resistance to antibiotics.
authors.affiliation: Molecular Genetics, Corporación Corpogen, Carrera 5 #66A-34, Bogotá, Colombia.
authors.forename: Mónica G
authors.initials: MG
authors.lastname: Huertas
authors.affiliation: Molecular Genetics, Corporación Corpogen, Carrera 5 #66A-34, Bogotá, Colombia.
authors.forename: Lina
authors.initials: L
authors.lastname: Zárate
authors.affiliation: Molecular Genetics, Corporación Corpogen, Carrera 5 #66A-34, Bogotá, Colombia.
authors.forename: Iván C
authors.initials: IC
authors.lastname: Acosta
authors.affiliation: Molecular Genetics, Corporación Corpogen, Carrera 5 #66A-34, Bogotá, Colombia.
authors.forename: Leonardo
authors.initials: L
authors.lastname: Posada
authors.affiliation: Molecular Genetics, Corporación Corpogen, Carrera 5 #66A-34, Bogotá, Colombia.
authors.forename: Diana P
authors.initials: DP
authors.lastname: Cruz
authors.affiliation: Molecular Genetics, Corporación Corpogen, Carrera 5 #66A-34, Bogotá, Colombia.
authors.forename: Marcela
authors.initials: M
authors.lastname: Lozano
authors.affiliation: Molecular Genetics, Corporación Corpogen, Carrera 5 #66A-34, Bogotá, Colombia.
authors.forename: María M
authors.initials: MM
authors.lastname: Zambrano
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000378:metabolism*; D018441:Biofilms / Q000254:growth & development*; D017173:Caenorhabditis elegans / Q000382:microbiology; D002482:Cellulose; D017353:Gene Deletion; D005798:Genes, Bacterial; D007711:Klebsiella pneumoniae / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D008826:Microbial Sensitivity Tests; D009876:Operon; D011135:Polysaccharides, Bacterial / Q000378:metabolism*; D014774:Virulence
chemical_list: D000900:Anti-Bacterial Agents; D011135:Polysaccharides, Bacterial; D002482:Cellulose