Cell wall polysaccharides F1SS disclose the relatedness of the genus Geosmithia with Eupenicillium and Talaromyces

Cell wall polysaccharides have been used as chemotaxonomic markers in a number of fungal genera. In this study, alkali-extractable and water-soluble cell wall polysaccharides F1SS were purified from cell walls of species of the genus Geosmithia. Chemical and H-1-NMR analyses of these polysaccharides revealed three different structures: (i) the polysaccharide from Geosmithia namylowskii was composed of beta-(1-->5)-galactofuranose chains attached to an alpha-(1-->2)-(1-->6)-mannan core identical to that isolated in several species of Eupenicillium, (ii) the polysaccharide from Geosmithia viridis was a glucomannogalactan similar to that obtained in Talaromyces flavus, and (iii) the polysaccharide from Geosmithia putterillii contained beta-(1-->5)-(1-->6)-galactofuranose with some units of the beta-(1-->5) residues substituted at position O-6 by single residues of galactofuranose; this galactan was attached to an alpha-(1-->2)-(1-->6)-mannan core. The taxonomy of the genus is discussed according to the polysaccharides F1SS, and our results are compared with the results of rDNA analyses in this genus.