Ligninolytic enzymes can participate in a multiple response system to oxidative stress in white-rot basidiomycetes: Fomes fomentarius and Tyromyces pubescens

The effect of menadione (MQ; 2-methyl-1,4-naphtoquinone) superoxide generating agent on the biological activity of two strains of white-rot fungi, Fomes fomentarius and Tyromyces pubescens, was determined. In this study 1 mM of MQ solution was added to 10-day-old idiophasic cultures. The application of MQ to F. fomentarius and T. pubescens cultures stimulated extracellular laccase (LAC) and manganese-dependent peroxidase (MnP) activities in comparison to the control values (without MQ). In the presence of MQ the concentration of oxalic acid in the medium of both fungi was dramatically decreased. MQ treatment also caused an increase of intracellular superoxide dismutase activity, formaldehyde and glutathione disulfide level in both strains. In the case of F. fomentarius, addition of MQ enhanced catalase activity. The rate of intra- and extracellular proteolysis decreased in F. fomentarius and increased in T. pubescens MQ treated cultures.