Natural disturbance and the activity of Trichoderma viride cellulase complexes

Abstract

The stability of organic matter-cellulase complexes was investigated using the enzymes of Trichoderma viride as a model. Soluble enzyme complexes were produced by reaction of cellulase with water-extractable substances from deciduous and pine litters. Insoluble enzyme complexes were produced by adsorption of cellulase to litter particles. Freeze-thaw and wet-dry events were used to evaluate the stability of the cellulase complexes. Soluble enzyme complexes generally sustained higher activity to repeated freeze-thaw events than uncomplexed enzymes. After 10 events, uncomplexed enzymes retained 42–56% of their initial activity while soluble enzyme complexes retained 60–145%. There were no consistent differences in response among enzyme types or extract sources. Among insoluble enzyme complexes, only β-glucosidase consistently displayed enhanced activity relative to free enzyme. Wet-dry events affected activity more severely than freeze-thaw ones. The stability of adsorbed cellulase varied among enzymes with β-glucosidase retaining 55–105% of its initial activity after 10 events, exocellulase retaining 12–60% after 10 events, and endocellulase 0–5%. The stability patterns of the enzyme complexes are suggested as being the result of two confounded processes: enzyme inactivation and complex dissociation.