Characterization Of Cellulolytic Multi-Enzymatic Complexes From Filamentous Fungi By Solid-State Fermentation Using Wheat Straw As Carbon Source

The aim of the present study is to identify thermostable and halostable enzymes from filamentous fungal strains. Trichoderma harzianum Aspergillus niger and Aspergillus flavus show the highest cellulolytic enzyme activity. The cellulolytic enzyme activities of these species were characterized using filter paper carboxymethyl cellulose and microcrystalline cellulose. The optimum temperature range for the activity of endoglucanase a component of the enzymatic complexes is 6570 C whereas the optimum range for exoglucanase is 5570 C. All the enzymes are thermostable at 4070 C. At a temperature of 60 C for all three species the optimal pH for endoglucanase and exoglucanase activity is 6 and 5.5 respectively. The results of a saline stability test indicate that more than 80 of the enzyme activity is retained for 1 h in 25 sodium chloride. Using carboxymethyl cellulose as substrate T. harzianum exhibits a Michaelis-Menten constant Km of 19.53 mg.mL-1 the lowest and maximum velocity Vmax of 0.4 mol.min-1.mL-1.The high halostability and thermostability of the cellulases produced by these fungal strains point to their potential use in harsh industrial processing conditions.