β-Glucosidase excretion in Trichoderma strains with different cell wall bound β-1,3-glucanase activities

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Abstract
Two different strains of T. pseudokoningii (SE1 A8 and SE1 D81) and T. viride QM 9123 release into the medium different proportions of the total .beta.-glucosidase activity produced. This observation correlates with the degree of .beta.-1,3-glucanase binding to the cell wall found for each strain. DEAE-Sephadex ion-exchange chromatography revealed 3 peaks of .beta.-1,3-glucanase activity. These 3 enzymes (enzyme I, enzyme II and enzyme III) differ in their extent of binding to the cell walls, their activity on isolated cell walls and Trichoderma .beta.-glucan, and their affinity for .beta.-glucan. Of these enzymes, enzyme II shows the largest variation in relative importance among the 3 strains and is located predominantly within the mural compartment. Enzyme II has the highest activity on and affinity for Trichoderma .beta.-glucan. Enzyme II is also the most active in releasing .beta.-glucosidase from cell walls of strain SE1 A8 (the strain excreting a high proportion of its .beta.-glucosidase into the culture fluid) as well as from strain SE1 D81 (little .beta.-glucosidase activity in the culture fluid). The action of .beta.-1,3-glucanase II on cell wall .beta.-glucan may be responsible for the in vivo release of cell wall bound .beta.-glucosidase into the culture fluid.
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