Improvement of Xylanase Production by Bacillus subtilis in Submerged Fermentation after UV and Chemicals Mutagenesis

Aims: Bacillus subtilis is one of the most utilized industrial microorganisms for its high capability of producing large amount of extracellular enzymes including xylanase. This extracellular enzyme has been used extensively for many years in food and detergents industry. In recent years, many attempts have been made for the improvement of microbial xylanase production by inducing mutagenesis. Thus, the objectives of this study are to produce mutants of B. subtilis using UV and chemicals mutagenesis, subsequently to elucidate the xylanase activity and finally to identify the most effective mutagenic agent for overproduction of this enzyme.

Methodology: In this study, ultraviolet (UV) irradiation and chemical mutagens of ethyl methanesulfonate (EMS) and acridine orange (AO) have been selected because of their simplicity of handling and cost-effectiveness as compared to recombinant DNA technology. The efficiency of these mutagenesis was further assessed in submerged fermentation in shake flask culture compared with the non-treated wild type control strain.

Results: Based on our results, B. subtilis that had been induced with 50 µg/mL of AO for 30 min exhibited the overproduction of xylanase with 1.580±0.027 U/mL in submerged fermentation. Indeed, the highest xylanase overproduction reached the maximum peak of 1.638±0.027 U/mL after 30 min of induction using 100 ug/mL of EMS. Apparently, when compared to the non-treated control, xylanase activity experienced the highest percentage of overproduction as much as 15.68% from EMS mutagenesis induced for 30 min in contrast to only 11.58% from B. subtilis that had been induced with 50 µg/mL of AO for 30 min.

Conclusion: In a nutshell, based on our results, EMS evidenced among the most promising mutagenic agent of inducing B. subtilis that capable of overproduction of xylanase to the greater extend as compared to UV irradiation and mutagenic agent of AO.