Abstract: Provided is a parent phytase variant, which relates to the technical field of protein engineering. The variant, relative to the parent phytase thereof, has one or more amino acid substitutions at positions corresponding to positions 295, 349, and 374 of SEQ ID NO: 1. Compared to the parent phytase, the variant has increased thermal stability.

Abstract: Provided is a thermostable glucose oxidase obtained by introducing at least one pair of disulfide bonds into an amino acid sequence of a wild-type Aspergillus niger glucose oxidase or a mutant Aspergillus niger glucose oxidase. The glucose oxidase is suitable for application in the fields of food, chemical engineering, medicine, agriculture and feeds.

Abstract: Disclosed herein is a method for expressing phytase in a filamentous fungus by using an optimized Escherichia coli phytase gene having a nucleotide sequence as shown in SEQ ID NO. 7 and a signal peptide having a nucleotide sequence as shown in SEQ ID NO. 12.

Abstract: Disclosed is a thermostable phytase, in which at least one pair of introduced disulfide bonds is included in the amino acid sequence of wild-type Escherichia coli phytase or mutant Escherichia coli phytase, and after the introduction, the properties of the phytase can be improved, especially the heat stability, steam stability and granulation stability, which are superior to those of the existing wild-type or mutant phytase; compared to the engineered phytase in which disulfide bonds are introduced, the heat stability is also significantly improved.

Abstract: Disclosed herein is a method for expressing phytase in a filamentous fungus by using an optimized Escherichia coli phytase gene having a nucleotide sequence as shown in SEQ ID NO. 7 and a signal peptide having a nucleotide sequence as shown in SEQ ID NO. 12.