Production of biodegradative enzymes by some thermophilic fungi of Agaricus bisporus compost

Abstract

Four most important thermophilic fungi, namely Humicola grisea, Humicola insolense, Chaetomium thermophilum and Scytalidium thermophilum, isolated from Agaricus bisporus compost and characterized by classical and molecular methods, were studied for production of the extracellular cellulases (endoglucanase, exoglucanase, β-glucosidase and xylanase) on four combinations of commonly used constituents (wheat straw, wheat bran and urea) under the solid-state fermentation conditions. Chaetomium thermophilum produced highest activities of endoglucanase and exoglucanase while Scytalidium thermophilum showed highest activity of β-glucosidase and xylanase. Humicola insolense and Humicola grisea were found poor producers of all the four enzymes. Very low activities of all the enzymes by the fungi were noticed on wheat straw alone as substrate. Supplementation with urea or wheat bran significantly increased the enzyme production, the latter showing greater enhancements. However all the fungi produced highest activities of all the degradative enzymes on whet straw supplemented with wheat bran and urea both. The study corroborates the importance of Scytalidium thermophilum and Humicola insolense in the compost preparation and also the nitrogen supplementation of the straw for optimum composting.