title: Poly-N-acetylglucosamine mediates biofilm formation and antibiotic resistance in Actinobacillus pleuropneumoniae.
abstract: Most field isolates of the swine pathogen Actinobacillus pleuropneumoniae form tenacious biofilms on abiotic surfaces in vitro. We purified matrix polysaccharides from biofilms produced by A. pleuropneumoniae field isolates IA1 and IA5 (serotypes 1 and 5, respectively), and determined their chemical structures by using NMR spectroscopy. Both strains produced matrix polysaccharides consisting of linear chains of N-acetyl-D-glucosamine (GlcNAc) residues in beta(1,6) linkage (poly-beta-1,6-GlcNAc or PGA). A small percentage of the GlcNAc residues in each polysaccharide were N-deacetylated. These structures were nearly identical to those of biofilm matrix polysaccharides produced by Escherichia coli, Staphylococcus aureus and Staphylococcus epidermidis. PCR analyses indicated that a gene encoding the PGA-specific glycoside transferase enzyme PgaC was present on the chromosome of 15 out of 15 A. pleuropneumoniae reference strains (serotypes 1-12) and 76 out of 77 A. pleuropneumoniae field isolates (serotypes 1, 5 and 7). A pgaC mutant of strain IA5 failed to form biofilms in vitro, as did wild-type strains IA1 and IA5 when grown in broth supplemented with the PGA-hydrolyzing enzyme dispersin B. Treatment of IA5 biofilms with dispersin B rendered them more sensitive to killing by ampicillin. Our findings suggest that PGA functions as a major biofilm adhesin in A. pleuropneumoniae. Biofilm formation may have relevance to the colonization and pathogenesis of A. pleuropneumoniae in pigs.
authors.affiliation: Department of Oral Biology, New Jersey Dental School, Newark, NJ 07103, USA.
authors.forename: Era A
authors.initials: EA
authors.lastname: Izano
authors.forename: Irina
authors.initials: I
authors.lastname: Sadovskaya
authors.forename: Evgeny
authors.initials: E
authors.lastname: Vinogradov
authors.forename: Martha H
authors.initials: MH
authors.lastname: Mulks
authors.forename: Kabilan
authors.initials: K
authors.lastname: Velliyagounder
authors.forename: Chandran
authors.initials: C
authors.lastname: Ragunath
authors.forename: William B
authors.initials: WB
authors.lastname: Kher
authors.forename: Narayanan
authors.initials: N
authors.lastname: Ramasubbu
authors.forename: Saïd
authors.initials: S
authors.lastname: Jabbouri
authors.forename: Malcolm B
authors.initials: MB
authors.lastname: Perry
authors.forename: Jeffrey B
authors.initials: JB
authors.lastname: Kaplan
mesh_terms: D016977:Actinobacillus pleuropneumoniae / Q000187:drug effects / Q000502:physiology*; D018829:Adhesins, Bacterial / Q000737:chemistry* / Q000187:drug effects / Q000302:isolation & purification / Q000502:physiology; D000667:Ampicillin / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics; D018441:Biofilms / Q000254:growth & development*; D002876:Chromosomes, Bacterial; D004351:Drug Resistance; D005685:Galactans / Q000737:chemistry / Q000378:metabolism*; D017353:Gene Deletion; D016695:Glycosyltransferases / Q000235:genetics; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D011135:Polysaccharides, Bacterial / Q000737:chemistry* / Q000302:isolation & purification / Q000502:physiology
chemical_list: D018829:Adhesins, Bacterial; D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D005685:Galactans; D011135:Polysaccharides, Bacterial; C023041:poly-N-acetylgalactosamine; D000667:Ampicillin; D016695:Glycosyltransferases