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

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 <i>Aspergillus fumigatus</i> are optimized in submerged fermentation (SmF). The most prolific strain (<i>A. fumigatus</i> KSA-2) produces the maximum xylanase at pH 9.0, 30 °C, after 7 days using yeast extract as a nitrogen supply. <i>Aspergillus fumigatus</i> 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.