Effect of Spruce Root Constituents on Extracellular Enzymes of Fomes annosus

Fractions of acetone extracts from heartwood, sapwood and wood from the reaction zone in roots of Norway spruce, attacked by Fomes annosus, were tested concerning their effect on the activity of cellulase, polygalacturonase, aryl-β-glucosidase and laccase, obtained from culture filtrates of the same fungus. A specific inhibition of polygalacturonase was recorded with the resinous fractions. The hydrolysing enzymes were more inhibited by the lignans of the reaction zone in the presence of fungal laccase than in the absence of laccase. The pH dependence of the inhibiting effect of phenols varied among the enzymes. The four enzymes were inhibited by partly different lignan fractions, and synergistic effects between minor compounds were indicated. The phenolic fractions inhibited weakly the biosynthesis of the enzymes. It was obvious that results from enzyme inhibition studies in vitro do not reflect the complicated mutual interrelationships between production and activity of the extracellular fungal enzymes and the chemical constituents of the host in vivo.