The degradation of cellulose and the production of cellulase, xylanase, mannanase and amylase by woodattacking microfungi

Thirty-six species of wood-inhabiting microfungi have been assayed for cellulase, xylanase, mannanase and amylase activity by the use of different test methods. The wood-degrading capabilities of the test organisms were previously known. Three of the species were unable to degrade birch wood. The other species represented three different degradation patterns, viz. 1) formation of soft rot cavities (Type 1 attack); 2) erosion of the wood cell walls (Type 2 attack);and 3) simultaneous Type 1 and Type 2 attack. With one exception, all species were able to degrade starch. The production of the enzymes cellulase, xylanase and mannanase was demonstrated for twenty of the wood-degrading species. Five of the wood-degrading species, which all produced soft rot cavities in birch wood, failed to exhibit any of the enzyme activities. The remaining wood-degrading species could be shown to produce one or two of the enzymes. One of the species which was unable to degrade birch wood produced xylanase. Cellulase and mannanase were not produced by any of these species. Twelve of the wood-degrading species appeared unable to degrade pure cellulose substrates when grown on agar media or in liquid cultures. Their only exhibition of cellulolytic activity was found in solid birch wood, where they formed soft rot cavities. These species have been referred to as "non-cellulolytic" soft rot fungi. Various explanations of the anomalous behaviour of these species are discussed