Liquid cultures with cellulose and solid state fermentation cultures on wheat straw of the white-rot fungi Pleurotus ostreatus and Trametes versicolor and the brown-rot fungus Piptoporus betulinus were assayed for the free and solid fraction-bound activity of lignocellulose-degrading enzymes. The majority of the ligninolytic enzymes laccase and Mn peroxidase was detected in the free fraction of P. ostreatus and T. versicolor. The endocleaving enzymes endo-1,4-beta-glucanase, endo-1,4-beta-mannanase and endo-1,4-beta-xylanase were detected almost exclusively in the free fraction, while significant amounts of 1,4-beta-glucosidase, cellobiohydrolase, 1,4-beta-xylosidase and 1,4-beta-mannosidase were present in the bound fraction depending on the mode of cultivation and the species. The bound enzymes accounted for 66% of the total activity in P. ostreatus straw cultures, 35% in T. versicolor and only 8% in P. betulinus. The enzymes also showed significant differences in freeze-drying stability. Hydrolases in general showed high stability, whereas laccase and Mn peroxidase of P. ostreatus were the least stable.

Laboratory of Biochemistry of Wood Rotting Fungi Institute of Microbiology ASCR Vídenská 1083 14220 Praha 4 Czech Republic