Effects of different bio-substrate treatments on polysaccharide synthesis and bioactivity of Auricularia heimuer

• Reed substrate significantly enhances the polysaccharide content in A. heimuer . • PGM gene's key role in A. heimuer polysaccharide synthesis on reed substrate. • Substrates significantly affected A. heimuer polysaccharide antioxidant activity. • A184 strain with higher polysaccharide and β-glucan was selected in reed substrate. The increasing shortage of traditional wood chip resources makes it increasingly important to develop new alternative cultivation substrates for mushroom, while different types of bio-substrate cultures have a greater impact on polysaccharide synthesis. Therefore, this study investigated the effects of two substrates, reed straw and sawdust on the growth and development, polysaccharide biosynthesis and antioxidant activity of Auricularia heimuer . The results showed that the polysaccharide (AHP) synthase gene were more susceptible to induction by reed substrate (SS), and PGM and PGI showed higher transcriptional expression levels during the fruiting period. The enzyme activities of strains UGPase and PGIase were overall higher in sawdust substrate (SS) than in RS, while PGMase was overall higher in RS than in SS. The correlation showed that the UGP gene might play a smaller role and PGM play a larger role in the synthesis of polysaccharides in the fruiting bodies of A. heimuer under both substrate cultures. A184-RS had the strongest scavenging ability of DPPH radicals and hydroxyl radicals, while A12-SS had the strongest scavenging ability of ABTS radicals and superoxide anions. This study provides a new reference for further analyzing the biosynthetic pathway of AHP, increasing the yield of AHP and the utilization of non-wood substrates by fungi.