title: The pel polysaccharide can serve a structural and protective role in the biofilm matrix of Pseudomonas aeruginosa.
abstract: Bacterial extracellular polysaccharides are a key constituent of the extracellular matrix material of biofilms. Pseudomonas aeruginosa is a model organism for biofilm studies and produces three extracellular polysaccharides that have been implicated in biofilm development, alginate, Psl and Pel. Significant work has been conducted on the roles of alginate and Psl in biofilm development, however we know little regarding Pel. In this study, we demonstrate that Pel can serve two functions in biofilms. Using a novel assay involving optical tweezers, we demonstrate that Pel is crucial for maintaining cell-to-cell interactions in a PA14 biofilm, serving as a primary structural scaffold for the community. Deletion of pelB resulted in a severe biofilm deficiency. Interestingly, this effect is strain-specific. Loss of Pel production in the laboratory strain PAO1 resulted in no difference in attachment or biofilm development; instead Psl proved to be the primary structural polysaccharide for biofilm maturity. Furthermore, we demonstrate that Pel plays a second role by enhancing resistance to aminoglycoside antibiotics. This protection occurs only in biofilm populations. We show that expression of the pel gene cluster and PelF protein levels are enhanced during biofilm growth compared to liquid cultures. Thus, we propose that Pel is capable of playing both a structural and a protective role in P. aeruginosa biofilms.
authors.affiliation: Department of Microbiology, University of Washington, Seattle, Washington, United States of America.
authors.forename: Kelly M
authors.initials: KM
authors.lastname: Colvin
authors.forename: Vernita D
authors.initials: VD
authors.lastname: Gordon
authors.forename: Keiji
authors.initials: K
authors.lastname: Murakami
authors.forename: Bradley R
authors.initials: BR
authors.lastname: Borlee
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Wozniak
authors.forename: Gerard C L
authors.initials: GC
authors.lastname: Wong
authors.forename: Matthew R
authors.initials: MR
authors.lastname: Parsek
mesh_terms: D000464:Alginates; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001422:Bacterial Adhesion; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D018441:Biofilms / Q000254:growth & development*; D005109:Extracellular Matrix / Q000502:physiology; D015964:Gene Expression Regulation, Bacterial; D008826:Microbial Sensitivity Tests; D050296:Microbial Viability / Q000187:drug effects; D011135:Polysaccharides, Bacterial / Q000235:genetics / Q000378:metabolism*; D011550:Pseudomonas aeruginosa / Q000187:drug effects / Q000254:growth & development / Q000502:physiology*; D014031:Tobramycin / Q000494:pharmacology
chemical_list: D000464:Alginates; D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D011135:Polysaccharides, Bacterial; D014031:Tobramycin