Fungal enzymatic activity in fruitbodies

This study describes a novel method for a culture-independent assay to test enzymatic activity of different fungal strains, using fresh fruitbody explants taken from metabolically active areas of fungi. Hydrolases (chitinases, exoglucanases) activity was measured using methylum-belliferyl-labeled substrate analogs; for oxidases (phenoloxidases, peroxidases) activity natural substrates such as guaiac gum or pyrogallol/H₂O₂ were used. To exclude potential enzymatic activity of bacteria attached to fruitbodies antibiotics were applied. The results suggest that most ectomycorrhizal fungi tested were able to form peroxidases. Some genera could also produce phenoloxidases, e.g. almost all strains of Lactarius, Russula, and Laccaria; other genera did not exude phenoloxidases into the test medium. This was the case for almost all strains of Boletaceae. Other genera did not show any genus specific enzyme activity pattern, e.g. Cortinarius and Tricholoma. Whether these enzymatic activities tested on fruitbodies of ectomycorrhizal fungi occur also in the soil and whether they have an ecological impact on fungal growth and tree nutrition has still to be studied.