Alkali-resistant xylanase and preparation method thereof

The invention relates to alkali-resistant xylanase and a preparation method thereof. The amino acid sequence of the alkali-resistant xylanase is shown as SEQ ID No.2, and the nucleotide sequence of the alkali-resistant xylanase is shown as SEQ ID No.1. According to the invention, ammonium sulfate precipitation, silica gel column chromatography and ion exchange column methods are utilized to separate and purify the alkali-resistant xylanase from a DX-THS3 strain. The alkali-resistant xylanase can still retain more than 80% of enzyme activity after being placed for 24 hours at normal temperature within the pH range of 5.0-11.0, and the residual enzyme activity can still reach 40% after being placed for 5 days at normal temperature in strong alkali buffer solutions with the pH values of 10, 11 and 12, so that the alkali-resistant xylanase is high in activity, high in stability and high in tolerance to metal ions and chemical reagents, and the alkali-resistant xylanase can be used for preparing the alkali-resista