Dynamics of α-glucan from Agrocybe cylindracea water extract at different developmental stages and its structure characteristics.

Polysaccharides are the important bioactive macromolecules in Agrocybe cylindracea, but their changes are as yet elusive during developmental process. This study investigated the dynamic changes of polysaccharides from A. cylindracea fruiting body water extract at four developmental stages and its structure characteristics. Results revealed that the polysaccharides from A. cylindracea water extract significantly increased at the pileus expansion stage and the increased fraction could be α-glucan. The further purification and identification indicated that this α-glucan was a glycogen. It had typical morphology of β particles with a molecular weight of 1375 kDa. Its backbone comprised α-D-(1 → 4)-Glcp and α-D-(1 → 4,6)-Glcp residues at a ratio of 5:1, terminated by α-D-Glcp residue. Rheological behavior suggested that it was a Newtonian fluid at the concentration of 1 %. In addition, despite both the glycogen and natural starch were composed of D-glucose, they exhibited the entirely distinct Maltese cross characteristic and unique crystalline structure. This study is the first to demonstrate the presence of abundant glycogen in the pileus expansion stage of A. cylindracea, which provides new insights on the change patterns of fungal polysaccharides.