Structural characterization of the cell wall d-glucans isolated from the mycelium of Botryosphaeria rhodina MAMB-05

Three d -glucans were isolated from the mycelium of the fungus Botryosphaeria rhodina MAMB-05 by sequential extraction with hot-water and hot aqueous KOH (2% w/v) followed by ethanol precipitation. Following their purification by gel permeation chromatography on Sepharose CL-4B, the structural characteristics of the d -glucans were determined by FT-IR and 13C NMR spectroscopy and, after methylation, by GC–MS. The hot-water extract produced a fraction designated Q1A that was a β-(1→6)- d -glucan with the following structure: Download : Download full-size image The alkaline extract, when subjected to repeated freeze–thawing, yielded two fractions: K1P (insoluble) that comprised a β-(1→3)- d -glucan with β- d -glucose branches at C-6 with the structure: Download : Download full-size image and K1SA (soluble) consisting of a backbone chain of α-(1→4)-linked d -glucopyranosyl residues substituted at O-6 with α- d -glucopyranosyl residues: Download : Download full-size image