Huge industrial application potential of xylanases is stalled due to lack of process suitable characteristics like thermostability, broad range pH stability, and high catalytic efficiency in the available enzymes. Current study presents the first ever report of a pH stable (pH 6-11) and thermostable (80-100 °C) xylanase from a novel strain of Aspergillus terreus S9. The xylanase was purified to homogeneity (6.67-fold) by ammonium sulphate precipitation, ion exchange chromatography, and molecular exclusion chromatography. SDS-PAGE analysis revealed an estimated molecular mass of ~33 kDa for the xylanase. Metal ions and surfactants such as K+, Ca2+, Mn2+, Mg2+, CTAB and Tween-80 enhanced the xylanase activity while Cu2+ and Hg2+ strongly inhibited the activity. Kinetic parameters i.e. Km, Vmax,Kcat and Kcat/Km of A. terreus S9 xylanase were 2.94 mg/ml, 285.71 μmol/min/mg, 1587.28 s-1and 539.89 ml/mg/s, respectively. The substrate specificity confirmed the true endoxylanolytic nature of xylanase. The conserved domain analysis, and Blastn and Blastx results showed that the xylanase belonged to GH10 family. A. terreus S9 xylanase may be used as model system for understanding the molecular basis of robust nature of enzymes, and the knowledge generated may help designing novel enzymes that are suitable for industrial applications.
Keywords: Aspergillus terreus S9; Enzyme-kinetics; Purification; Xylanase; pH-thermostability.
Copyright © 2018 Elsevier B.V. All rights reserved.