Effects of extracellular enzymes secreted by wild edible fungi mycelia on the surface properties of local soil colloids

The extracellular enzymes secreted by wild edible fungi mycelia participate in a series of physiochemical reactions in soil, thereby changing the surface properties of local soil colloids irreversibly. However, the reaction process and mechanism were generally ignored, leading to a misunderstanding of local soil functions. In this work, the soil samples collected from areas where growing wild edible fungi were selected as model substances, and the effects of extracellular enzymes (alpha-amylase, beta-glucosidase, and peroxidase) secreted by wild edible fungi mycelia on the physicochemical properties of soil colloids were explored. After adding extracellular enzymes, the pores and fissures between the lamellar sheets were observed more obviously and the surface heights decreased significantly, especially after adding alpha-amylase. The addition of extracellular enzymes increased the electronegativity and the suspension stability of soil colloids owing to the decrease in their polarity and water solubility. The added extracellular enzymes might be adsorbed on the organic and inorganic components in soil colloids and could promote the decomposition of soil organic matter, thereby changing the physicochemical properties of soil colloids and improving the soil quality. The results will lay a theoretical foundation for understanding the soil function in the areas where growing wild edible fungi.