title: Characterization of colony morphology variants isolated from Pseudomonas aeruginosa biofilms.
abstract: In this study, we report the isolation of small, rough, strongly cohesive colony morphology variants from aging Pseudomonas aeruginosa PAO1 biofilms. Similar to many of the P. aeruginosa colony morphology variants previously described in the literature, these variants autoaggregate in liquid culture and hyperadhere to solid surfaces. They also exhibit increased hydrophobicity and reduced motility compared to the wild-type parent strain. Despite the similarities in appearance of our colony morphology variant isolates on solid medium, the isolates showed a range of responses in various phenotypic assays. These variants form biofilms with significant three-dimensional structure and more biomass than the wild-type parent. To further explore the nature of the variants, their transcriptional profiles were evaluated. The variants generally showed increased expression of the psl and pel loci, which have been previously implicated in the adherence of P. aeruginosa to solid surfaces. When a mutation in the psl locus was introduced into a colony morphology variant, the colony morphology was only partially affected, but hyperadherence and autoaggregation were lost. Finally, similar colony morphology variants were found in isolates from cystic fibrosis patients. These variants displayed many of the same characteristics as the laboratory variants, suggesting a link between laboratory and cystic fibrosis biofilms.
authors.affiliation: University of Iowa, Department of Microbiology, 540E EMRB, Iowa City, IA 52242.
authors.forename: Mary Jo
authors.initials: MJ
authors.lastname: Kirisits
authors.forename: Lynne
authors.initials: L
authors.lastname: Prost
authors.forename: Melissa
authors.initials: M
authors.lastname: Starkey
authors.forename: Matthew R
authors.initials: MR
authors.lastname: Parsek
mesh_terms: D001422:Bacterial Adhesion; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D018441:Biofilms / Q000145:classification* / Q000254:growth & development*; D003470:Culture Media; D003550:Cystic Fibrosis / Q000382:microbiology; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D057927:Hydrophobic and Hydrophilic Interactions; D009068:Movement; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods; D010641:Phenotype; D011552:Pseudomonas Infections / Q000382:microbiology; D011550:Pseudomonas aeruginosa / Q000145:classification* / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: D001426:Bacterial Proteins; D003470:Culture Media