Studia Forestalia Suecica

Thirty-six species o f wood-inhabiting microfungi have been assayed for cellulase, xylanase, mannanase and amylase activity by the use o f different test methods. The wood-degrading capabilities of the test organisms were previously known. Three o f the species were unable t o degrade birch wood. The other species represented three different degradation patterns, viz. I ) 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 t o degrade starch. The production of the enzymes cellulase, xylanase and mannanase was demonstrated for twenty o f the wood-degrading species. Five of the wood-degrading species, which all produced soft rot cavities in birch wood, failed t o exhibit any of the enzyme activities. The remaining wood-degrading species could be shown to produce one or two o f the enzymes. One of the species which was unable t o 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 o f cellulolytic activity was found in solid birch wood, where they formed soft rot cavities. These species have been referred t o as "non-cellulolytic" soft rot fungi. Various explanations of the anomalous behaviour o f these species are discussed. Ms received 27th February, 1974