Production of extracellular enzyme by the white-rot fungus Dichomitus squalens in cellulose-containing liquid culture

Abstract

The white-rot fungus Dichomitus squalens has been found to be a potent endo-1,4-β- d-glucanase producer when cultivated on crystalline cellulose in the presence of 0.2% proteose peptone. Several activities were detected in culture supernatant, including endo-1,4-β- d-glucanase [1,4-(1,3;1,4)-β- d-glucan 4-glucanohydrolase, EC 3.2.1.4], d-xylanase (endo-1,3-β- d-xylanase, 1,3-β- d-xylan xylanohydrolase, EC 3.2.1.32), exopoly- d-galacturonase [poly(1,4-α- d-galacturonide) galacturonohydrolase, EC 3.2.1.67], cellobiose dehydrogenase [cellobiose:quinone oxidoreductase, see d-glucose dehydrogenase (acceptor), d-glucose:(acceptor) 1-oxidoreductase, EC 1.1.99.10], β- d-glucosidase (β- d-glucoside glucohydrolase, EC 3.2.1.21) and exo-cellobiohydrolase (1,4-β- d-glucan cellobiohydrolase, EC 3.2.1.91), using 4-nitrophenyl-β- d-cellobioside as a substrate. A crude enzyme preparation was obtained by ammonium sulphate (80% saturation) precipitation of soluble protein. In spite of the presence of both endo- and exo-β- d-glucanase activities, degradation of crystalline cellulose by the enzymic preparation remained weak.