HYDROLYTIC PROPERTIES OF EXTRACELLULAR CELLULASES FROM PLEUROTUS-OSTREATUS

Pleurotus ostreatus mycelium produced extracellular cellulases when gr own on ground wheat straw. No cellulase activity was detectable when g lucose or aqueous extracts of vegetable material were used as substitu tes for straw in culture media. The specific activity of excreted cell ulases did not vary significantly by increasing the straw concentratio n from 1 to 6%. Chromatographic fractionation of extracellular protein s gave rise to five fractions with cellulolytic activity. The hydrolyt ic properties of these partially purified fractions were analysed by u sing several substrates (carboxymethylcellulose, cellobiose, p-nitroph enyl-beta-D-cellobioside, p-nitrophenyl-beta-D-lactoside). The results indicate that the cellulase system of P. ostreatus includes at least a beta-glucosidase, two endocellulases, an exoglucohydrolase and an ex ocellobiohydrolase.