Comparative activities of oxidoreductase enzymes in tissue extracts of crop plants and in culture fluids of fungal mycelia

Activities of oxidoreductase enzymes from plant tissue extracts (PE, 1.2% dry wt input) and culture fluids of basidiomycete fungi (CF, 0.5% mycelial dry wt) were assayed spectrophotometrically. PE of 11 plants showed large to negligible peroxidase, moderate monophenol monooxygenase, and poor laccase reactions. The formation of Mn3+ chelates and bleaching reactions of aromatic dyes indicated ligninolytic capacities in PE. Hydroxylations and oxidations of aromatic ring structures, and the H2O2-dependent oxidation of veratryl alcohol were detected by HPLC. In comparison to PE, CF showed a 40-fold laccase production but only one-third of all oxidative activities together. It is concluded that crop plant tissue may be a source of several readily available oxidoreductases and enzyme/mediator systems. Some of their reactions have been studied extensively only in microbial cultures.