title: Microcolony formation: a novel biofilm model of Pseudomonas aeruginosa for the cystic fibrosis lung.
abstract: Pseudomonas aeruginosa colonizing the lung of cystic fibrosis patients is responsible for a decline in health and poor prognosis for these patients. Once established, growth of P. aeruginosa in microcolonies makes it very difficult to eradicate the organisms by antimicrobial treatment. An artificial sputum medium was developed to mimic growth of P. aeruginosa in the cystic fibrosis lung habitat and it was found that the organisms grew in tight microcolonies attached to sputum components. Several genes, such as algD, oprF and lasR but not fliC, were required for tight microcolony formation. Among the sputum components, amino acids, lecithin, DNA, salt and low iron were required for tight microcolony formation. Amino acids were also shown to be responsible for various other cystic-fibrosis-specific phenotypes of P. aeruginosa, such as diversification of colony morphology, alterations in LPS structure and hyperexpression of OprF. Since the amino acid content of sputum is elevated in severe lung disease, it is suggested that the tight microcolony biofilm is maintained in these conditions and that they contribute to the vicious cycle of disease severity and failure to eradicate the organism. Thus, growth of P. aeruginosa in artificial sputum medium is an appropriate model of chronic lung colonization and may be useful for evaluating therapeutic procedures and studying antibiotic-resistance mechanisms.
authors.affiliation: Microbiology and Tumor Biology Center (MTC), Karolinska Institutet, 17177 Stockholm, Sweden 2,3Department of Cell Biology and Immunology2 and Department of Microbiology3, Gesellschaft für Biotechnologische Forschung, 38124 Braunschweig, Germany 4Department of Microbiology, University of Guelph, Canada N1G2W1.
authors.forename: Dinesh D
authors.initials: DD
authors.lastname: Sriramulu
authors.affiliation: Microbiology and Tumor Biology Center (MTC), Karolinska Institutet, 17177 Stockholm, Sweden 2,3Department of Cell Biology and Immunology2 and Department of Microbiology3, Gesellschaft für Biotechnologische Forschung, 38124 Braunschweig, Germany 4Department of Microbiology, University of Guelph, Canada N1G2W1.
authors.forename: Heinrich
authors.initials: H
authors.lastname: Lünsdorf
authors.affiliation: Microbiology and Tumor Biology Center (MTC), Karolinska Institutet, 17177 Stockholm, Sweden 2,3Department of Cell Biology and Immunology2 and Department of Microbiology3, Gesellschaft für Biotechnologische Forschung, 38124 Braunschweig, Germany 4Department of Microbiology, University of Guelph, Canada N1G2W1.
authors.forename: Joseph S
authors.initials: JS
authors.lastname: Lam
authors.affiliation: Microbiology and Tumor Biology Center (MTC), Karolinska Institutet, 17177 Stockholm, Sweden 2,3Department of Cell Biology and Immunology2 and Department of Microbiology3, Gesellschaft für Biotechnologische Forschung, 38124 Braunschweig, Germany 4Department of Microbiology, University of Guelph, Canada N1G2W1.
authors.forename: Ute
authors.initials: U
authors.lastname: Römling
mesh_terms: D000596:Amino Acids / Q000378:metabolism; D000818:Animals; D001422:Bacterial Adhesion; D018441:Biofilms / Q000254:growth & development*; D003470:Culture Media; D003550:Cystic Fibrosis / Q000382:microbiology*; D006801:Humans; D008070:Lipopolysaccharides / Q000378:metabolism; D008168:Lung / Q000382:microbiology*; D008954:Models, Biological; D010641:Phenotype; D011550:Pseudomonas aeruginosa / Q000145:classification / Q000235:genetics / Q000502:physiology; D013183:Sputum / Q000737:chemistry / Q000382:microbiology*; D013552:Swine
chemical_list: D000596:Amino Acids; D003470:Culture Media; D008070:Lipopolysaccharides