Purification and Characterization of Xylanase Produced by Aspergillus fumigatus Isolated from the Northern Border Region of Saudi Arabia

Abstract

The purpose of the current work is to produce xylanase from certain agro-industrial wastes in an efficient and effective manner. The culture conditions for three strains of Aspergillus fumigatus are optimized in submerged fermentation (SmF). The most prolific strain (A. fumigatus KSA-2) produces the maximum xylanase at pH 9.0, 30 °C, after 7 days using yeast extract as a nitrogen supply. Aspergillus fumigatus KSA-2 is utilized to produce xylanase at optimum conditions from several agro-industrial wastes. Wheat bran is found to be the most fermentable material, yielding 66.0 U per gram dry substrate (U/gds). The generated xylanase is partly purified using 70% ammonium sulphate, yielding 40 g of dry enzyme powder from 400 g wheat bran. At pH 6.0 and 45 °C, the synthesized xylanase displayed its maximum activity (20.52 ± 1.714 U/mg). In the current study, the effect of ions and inhibitors on xylanase activity is investigated. Both Cu2+ and Mn2+ ions boost the specific activity over the control by 10.2% and 128.0%, respectively. The xylanase enzyme generated has a maximum activity of 4.311 ± 0.36 U/mL/min and the greatest specific activity of 20.53 ± 1.714 U/mg for birchwood xylan, showing a strong affinity for this substrate as opposed to the other xylan and non-xylan substrates.