Structure of a novel exopolysaccharide produced by Burkholderia vietnamiensis, a cystic fibrosis opportunistic pathogen

Burkholderia vietnamiensis belongs to the Burkholderia cepacia complex and is an opportunistic pathogen for cystic fibrosis patients. As many other Burkholderia species, it has a mucoide phenotype, producing abundant exopolysaccharide. In general, polysaccharides contribute to bacterial survival in a hostile environment, are recognised as virulence factors and as important components in biofilm formation. The primary structure of the exopolysaccharide produced by B. vietnamiensis LMG 10929 was determined mainly by use of 1D and 2D NMR spectroscopy and ESI mass spectrometry. The polymer consists of the trisaccharidic backbone 3)-beta-D-Glcp-(1→4)-alfa-D-Glcp-(1→3)-alfa-L-Fucp-(1→ with the side chain alfa-D-Glcp-(1→4)-alfa-D-GlcAp-(1→3)-alfa-L-Fucp-(1→ linked to C-3 of the alfa-D-Glcp residue. The polysaccharide also bears acetyl substituents on about 20% of its repeating units and on at least two different positions. The presence of fucose residues is a novel structural feature among the exopolysaccharides produced by species of the B. cepacia complex.