Comparison of cell-wall polysaccharides from Nectria cinnabarina with those from the group of Nectria with Sesquicillium anamorphs

Alkali-extractable and water-soluble polysaccharides were purified from cell walls of five species of Sesquicillium or its teleomorphs, Nectria lasiacidis and Nectria impariphialis, and from Nectria cinnabarina, the type species of Nectria, a heterogeneous genus that belongs to the Hypocreales. Methylation and NMR analyses for determination of linkage types and structure were performed and indicated differences between the polysaccharides purified during the present study and those isolated from other nectrioid fungi, namely the presence of 5-O-substituted galactofuranose (-->5)-Galf-(l -->) in the main chain together with 2,6-di-O-substituted galactofuranose (--> 2,6)-Galf-(1 -->) residues in Sesquicillium buxi and Sesquicillium pseudosetosum. The polysaccharide from N. impariphialis was similar to those obtained from the above species, although an additional residue of 6-O-substituted glucopyranose (--> 6)-Glcp(1 -->), was detected in some side chains. In N. lasiacidis and Sesquicillium candelabrum the polysaccharide contained an additional branching point of 5,6-di-O-substituted galactofuranose (--> 5,6)-Galf-(1 -->) linked to terminal N-acetylglucosamine GlcNAc-(1 -->). These chains were linked to a small mannan core. All these polysaccharides showed major differences to the polysaccharide of N. cinnabarina, which was formed by a main chain of (1 --> 6)-beta -linked galactofuranose units almost fully branched at positions 2-O by either single residues of glucopyranose or acidic chains containing glucuronic acid and mannose.