Fungal Strain Improvement of Aspergillus brasiliensis for Overproduction of Xylanase in Submerged Fermentation through UV Irradiation and Chemicals Mutagenesis

摘要

Aims: One of the major outlooks in biotechnology is to enhance enzymes production using various strains of microorganisms. Filamentous fungi such as Aspergillus brasiliensis has been found to be the most promising strain as it produces extracellular enzymes such as xylanase which is easily extracted as compared to other intracellular enzymes. Xylanase has been involved in many industrial applications such as pulp and paper, baking, detergent, food and beverage. Hence, the main objectives of this study are to improve the production of xylanase by A. brasiliensis using physical and chemicals mutagenesis and thus to determine the most effective mutagenesis approach for the overproduction of xylanase. Methodology: In this study, ultraviolet (UV) irradiation and chemical mutagens including ethyl methane sulfonate (EMS) and N-methyl-N’-nitro-N-nitrosoguanidine (MNNG) were selected as the random mutagenesis methods due to their cost-effectiveness as compared to recombinant DNA technology. Results: The wild type strain was able to produce 3.097±0.089 U/mL of xylanase at 48 h of submerged fermentation. In contrast, the highest xylanase overproduction of 4.86±0.095 U/mL was achieved from mutant of A. brasiliensis after being exposed to UV for 20 min from a distance of 10 cm. In fact, this UV exposed A. brasiliensis mutant experienced the highest percentage of increment with 56.93% on the overproduction of xylanase as compared to the mutants with the exposure of 150 μg/mL of EMS for 90 min and 150 μg/mL of MNNG for 30 min with the increment of only 1.34% and 17.14%, respectively. Conclusion: In conclusion, UV mutagenesis was among the most effective mutagenic approach in inducing the overproduction of xylanase by A. brasiliensis compared to EMS and MNNG in this study, respectively.