Various forms of PGA appear to differ in their molecular weight, in the degree of N-deacetylation of the GlcNAc residues, and in the presence of O-succinate substituents. These polysaccharides, usually referred to as PGA, PNAG or PIA (polysaccharide intercellular adhesin), consist of linear chains of N-acetyl-D-glucosamine (GlcNAc) residues in β(1,6) linkage (hereafter referred to as PGA). pleuropneumoniae biofilms contain a hexosamine-rich polysaccharide that is functionally and genetically related to extracellular polysaccharide adhesins produced by Escherichia coli, Staphylococcus aureus and S. pleuropneumoniae form tenacious biofilms on abiotic surfaces in vitro. pleuropneumoniae colonizes the lungs of pigs and causes the severe and contagious respiratory disease swine pleuropneumonia. Īctinobacillus pleuropneumoniae is a member of the Pasteurellaceae, a family of Gram-negative bacteria that includes many important human and animal pathogens. Polysaccharide is a major component of the EPS matrix in most bacterial biofilms. The EPS matrix also contributes to the increased resistance to antibiotics and host defenses exhibited by biofilm cells.

In addition to its structural role, the EPS matrix provides biofilm cells with a protected microenvironment containing dissolved nutrients, secreted enzymes, DNA, and bacteriophages. This matrix, also referred to as the slime layer, glycocalyx, or extracellular polymeric substance (EPS) matrix, can comprise up to 90 % of the biofilm biomass. Bacterial cells in a biofilm are encased in a self-synthesized, extracellular hydrogel matrix that holds the cells together in a mass and firmly attaches the bacterial mass to the underlying surface. Surface-associated colonies of bacteria known as biofilms play a role in the pathogenesis of many chronic infections. Biofilm formation may have relevance to the colonization and pathogenesis of A. Our findings suggest that PGA functions as a major biofilm adhesin in A. Treatment of IA5 biofilms with dispersin B rendered them more sensitive to killing by ampicillin. 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. pleuropneumoniae field isolates (serotypes 1, 5 and 7). pleuropneumoniae reference strains (serotypes 1-12) and 76 out of 77 A. 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. These structures were nearly identical to those of biofilm matrix polysaccharides produced by Escherichia coli, Staphylococcus aureus and S. A small percentage of the GlcNAc residues in each polysaccharide were N-deacetylated. Both strains produced matrix polysaccharides consisting of linear chains of N-acetyl-D-glucosamine (GlcNAc) residues in β(1,6) linkage (poly-β-1,6-GlcNAc or PGA). pleuropneumoniae field isolates IA1 and IA5 (serotypes 1 and 5, respectively), and determined their chemical structures by using NMR spectroscopy.

We purified matrix polysaccharides from biofilms produced by A. Most field isolates of the swine pathogen Actinobacillus pleuropneumoniae form tenacious biofilms on abiotic surfaces in vitro.

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