Purification and Characterization of a Xylanase Produced by Chaetomium thermophile NIBGE

Xylanase was produced by growing Chaetomium thermophile NIBGE in a submerged liquid culture using wheat straw and urea as carbon and nitrogen sources respectively. The xylanase was purified to electrophoretic homogeneity after ammonium sulphate precipitation, anion exchange chromatography by FPLC and gel filtration. The molecular mass of this xylanase BII was 50 kDa. The pH and temperature optima were 6.5 and 70 °C respectively. The xylanase BII showed reasonable stability at high pH and 65 °C temperature. Some metal ions and EDTA caused little inhibition at low concentrations but complete inhibition was observed at concentrations higher than 2 mM. The Km and Vmax values with oat spelt xylan as the substrate were found to be 12.5 mg/ml and 83.3 IU/mg protein, respectively. Liberation of reducing sugars from commercial paper pulp samples suggest the feasibility of a biopulping process using this xylanase.