Hyper-production and Characterization of Exoglucanase Through Physical, Chemical, and Combined Mutagenesis in Indigenous Strain of Thermophilic Aspergillus fumigatus.

Abstract

The present study explored the optimization of exoglucanase production from waste cellulosic biomaterials using microbial cellulases, focusing on enhancing enzyme efficiency through mutagenesis techniques. Research illustrated the hyper-production and quantitative characterization of an exoglucanase from a thermophilic Aspergillus fumigatus strain via physical and chemical mutagenesis under optimized fermentation conditions. Physical mutagenesis via UV irradiation (15-min exposure) yielded the highest activity (96.57 U/mL), while chemical mutagenesis with ethyl methane sulfonates (250 µg/mL) resulted in 69.61 U/mL activity. Combined mutagenesis using EMS (250 µg/mL) concentration with 15-min UV exposure significantly enhanced exoglucanase production to 136.19 U/mL as compared to the native enzyme 52.46 U/mL. Among various cellulosic substrates, peanut shells exhibited superior suitability for exoglucanase production reaching a maximum activity of 202.41 U/mL. Fermentation parameters including pH, temperature, incubation period, and inoculum size were optimized, leading to a substantial increase in exoglucanase activity of 285.28 U/mL using response surface methodology followed by gel filtration chromatography. The mutant exoglucanase was characterized by its enhanced activities with a higher Vmax (0.6515) and lower Km (0.3142) than those of native enzyme. The characterization has confirmed the temperature and pH tolerance of the mutant enzyme, as well as its tolerance to metal ions and substrate concentrations. This study showed how mutagenesis-driven optimization could provide a means to enhance exoglucanase production from cellulosic biomass, with a rational insight toward enzyme kinetics and applications toward bioenergy generation.