Mutation-Screening in Xylanase-Producing Strains by Ion Implantation

With ion implantation (N⁺, energy 10 keV and dosage 1.56 × 10¹⁵ N⁺ cm^-2), a high xylanase-producing strain Aspergillus niger N212 was selected. Based on an orthogonal experiment, an optimal fermentation condition was designed for this high-yield strain. The suitable medium was composed of 8% corncob; 1.0% wheat bran; 0.1% TWEEN20; 0.5% (NH₄)₂SO₄; 0.5% NaNO₃; 0.5% FeSO₄, 7.5 × 10^-4; MnSO₄·H₂O, 2.5 × 10^-4; ZnSO₄, 2.0 × 10^-4; CoCl₂, 3.0 × 10^-4. At present, under our experiment condition, xylanase activity of Aspergillus niger N212 reached a level of 600 IU/ml, almost increased by 100% in xylanase production and the time of yielding xylanase was largely reduced to 12 h at 28 °C.