A Thermostable Crude Endoglucanase Produced byAspergillus fumigatusin a Novel Solid State Fermentation Process Using Isolated Free Water

Abstract

Aspergillus fumigatuswas grown on chopped wheat straw in a solid state fermentation (SSF) process carried out in constant presence of isolated free water inside the fermentation chamber. The system allowed maintaining a constant vapor pressure inside the fermentor throughout the fermentation process. Crude endoglucanase produced byA. fumigatusunder such conditions was more thermostable than previously reported enzymes of the same fungal strain which were produced under different conditions and was also more thermostable than a number of other previously reported endoglucanases as well. Various thermostability parameters were calculated for the crude endoglucanase. Half lives (T1/2) of the enzyme were 6930, 866, and 36 min at 60°C, 70°C, and 80°C, respectively. Enthalpies of activation of denaturation (ΔHD*) were 254.04, 253.96, and 253.88 K J mole−1, at 60°C, 70°C and 80°C, respectively, whereas entropies of activation of denaturation (ΔSD*) and free energy changes of activation of denaturation (ΔGD*) were 406.45, 401.01, and 406.07 J mole−1 K−1and 118.69, 116.41, and 110.53 K J mole−1at 60°C, 70°C and 80°C, respectively.