Structural characterization of a cell wall polysaccharide from Penicillium vermoesenii: chemotaxonomic application

Abstract

The water-soluble polysaccharides (F1SS) obtained from the alkali extracts of the cell wall of two strains of Penicillium vermoesenii Biourge, Fusarium javanicum Koorders, Fusarium solani (Martius) Saccardo, and Fusarium oxysporum Schlechtendahl represented 8.7 to 10.7% of the dry cell wall material. All polysaccharides were composed of galactose (22.0-27.4%), glucose (18.4-30.3%), mannose (7.8-23.1%), and glucuronic acid (3.0-6.0%, except in F. oxysporum that contained 16.8%). Methylation analysis and 1H-NMR spectra of the polysaccharides of these fungi were similar except for F. oxysporum, which showed a higher peak of glucuronic acid than of glucose. The chemical and structural analyses performed indicated that F1SS polysaccharides of the species studied have a skeleton of beta-(1–>6) galactofuranose, fully substituted at positions O-2 by a single residue of glucopyranose or by short side chains containing one glucuronic acid residue and beta-mannopyranose. This polysaccharide is linked to a mannose core consisting of a short chain of alpha-(1–>6)-linked D-mannopyranose. Immunological methods confirm the structural relatedness among these polysaccharides. No similarities were found with the 1H-NMR spectra of F1SS polysaccharides from other species of Penicillium or Gliocladium. These results show that P. vermoesenii is closer to the genus Fusarium than to Penicillium or Gliocladium.Key words: Penicillium vermoesenii, cell wall polysaccharides, chemotaxonomy, NMR, polyclonal antibodies.