Changes in Carbohydrates and Organic Acids during Development of Mycelium and Fruit-bodies of Hiratake Mushroom (Pleurotus ostreatus)

Abstract

Changes in distribution of low molecular weight carbohydrates, polysaccharides and organic acids were followed in the mycelium and fruit-bodies of Hiratake mushroom (Pleurotus ostreatus) grown on a glucose-peptone medium. (1) The total free sugar content in mycelium during development was found in the range of 4.62-19.46% in stipes 8.26-22.32%, and in pilei 5.50-12.84% in dry materials, respectively, while the total sugar alcohol content in mycelium during it 0.84-5.13%, in stipes 2.99-3.79%, and in pilei 2.13-3.39% respectively. In this mushroom, trehalose, mannitol, glucose, fructose and arabitol were identified, and trehalose, and mannitol were found to be major among them. Trehalose and mannitol were supposed to function as the main translocate carbohydrate. (2) The content of polysaccharides in mycelium during development was found in the range of 47.92-55.56%, in stipes 46.78-48.54%, and in pilei 41.18-42.07% in dry materials, respectively. The four polysaccharide fraction contents, that is, hot alkali-soluble fraction, alkali-soluble, acid-insoluble fraction (S-glucan), formic acd-soluble fraction (R-glucan) and alkali-soluble, acid-soluble fraction, did not change during development. Acetic acid-soluble fraction predominated in the polysaccharide fractions of the mycelium, but was the minor constituent in fruit-bodies. Acetic acid-soluble fraction accumulated in mycelium was used as the major transient storage carbohydrate for fruit-body growth. Utilization of chitin in mycelium also occurred during development. (3) The organic acid content in myceium during development was found in the range of 0.82-2.16%, in stipes 4.97-5.18%, and in pilei 4.12-4.46% in dry materials, respectively. The organic acid contents in fruit-bodies were 1.97-2.40 times as much as those in mycelium. In this mushroom, elevein kinds of organic acids were identified, Pyroglutamic, malic, succinic and fumaric acids were found to be predominant in mycelium, and malic, citric, pyroglutamic, succinic and fumaric acids were found to be predominant in fruit-bodies. There were remarkable differences in the distribution patterns of their organic acid compositions among mycelium, stipes and pilei.