Preparation method for xylanase

The invention relates to the technical field of microbial fermentation and enzyme engineering, in particular to a preparation method feeding xylanase produced through fermentation of pichia pastoris engineering bacteria. The invention aims at providing the preparation method for engineering bacteria. The preparation method comprises the steps of bacteria activation, cultivation expansion, secondary cultivation expansion, fermentation, filtration, ultrafiltration and concentration, preservative addition, homogeneous mixing, refined filtration, degerming and pouring. The yield of the xylanase is improved and a better heat resistance is achieved by choosing suitable PH, suitable fermentation time and suitable culture medium, the fermentation time is shortened, and industrial production is facilitated.