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

Abstract

Aspergillus fumigatus was 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 by A. fumigatus under 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 (T 1/2) of the enzyme were 6930, 866, and 36 min at 60°C, 70°C, and 80°C, respectively. Enthalpies of activation of denaturation (ΔH D*) 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 (ΔS D*) and free energy changes of activation of denaturation (ΔG D*) were 406.45, 401.01, and 406.07 J mole−1 K−1 and 118.69, 116.41, and 110.53 K J mole−1 at 60°C, 70°C and 80°C, respectively.

Gamma Rays Mediated Mutagenesis of Super Koji (Aspergillus oryzae) to enhance the Thermostability and Production of CMCases: Process Scale-up at Pilot Level

“…The endoglucanase from mutant 60(5) was comparatively more thermostable as it showed t½ of 14.83 min at 60 C which was 4 folds higher than parental strain. These results were also supported by study conducted by [30]and reported the t½of endoglucanases from parental A. oryzae strain was 2 min at 56 C. However, the half-lives of endoglucanase isolated from Aspergillus fumigatus was comparatively higher with t½of 6930, 866 and 36 min at 60 C, 70 C and 80 C, respectively [9]. After incubating the enzyme at higher temperature for extended time and cooling, the irreversible unfolding and reversible inactivated state can be analysed by T m and t½ [49].…”

“…Endoglucanases are the largest groups of enzymes constituting third group of enzyme world-wide and used commercially for more than 30 years [9]. Cellulases are used in various industrial applications such as alcohol production, fruits and vegetables extraction, brewing and malting [10], animal feed, food, paper and pulp, textile and laundry industries, agriculture and even for academic and research purposes [11].…”

Biochemical Characterization, Thermal Stability, and Partial Sequence of a Novel Exo-Polygalacturonase from the Thermophilic Fungus Rhizomucor pusillus A13.36 Obtained by Submerged Cultivation

“…In general, the variation of entropy is positive due to an increase in disorder, while low values of Δ S ( d ) suggest the exposure of nonpolar side chains which causes the order of water molecules in the form of clathrates or cages [39]. The positive change in entropy of denaturation was above 200 J/(mol·K) which is less than the reported value for an endoglucanase from A. fumigatus [26] which is in the range of 400 J/(mol·K) and very different from the values obtained for a carboxymethylcellulase from A. niger , situated between −200 and −210 J/(mol·K) [39], and for a β -glucosidase from F. solani , with values around −170 J/(mol·K) [40]. …”

Identification and characterization of thermostable endo‐polygalacturonase II B from Aspergillus luchuensis

“…The enzyme activity was measured and residual activity was confirmed after 24 hr treatment at 40°C. The thermostability of PgaB was analyzed by the Arrhenius plot (Siddiqui, Saqib, Rashid, & Rajoka, 2000) and half-lives (T 1/2 ) of PgaB at different temperatures were calculated according to a previous report (Saqib et al, 2012).…”