The present invention relates to variant phytase enzymes and their use thereof.

The present invention provides mutant cereal plants and mature grain thereof, characterised by enhanced levels of the enzyme phytase in the grain, and methods for inducing, detecting and selecting the mutant cereal plants. The invention further relates to animal feed comprising said grain having enhanced amounts of phytase.

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.

The present invention provides mutant cereal plants and mature grain thereof, characterised by enhanced levels of the enzyme phytase in the grain, and methods for inducing, detecting and selecting the mutant cereal plants. The invention further relates to animal feed comprising said grain having enhanced amounts of phytase.

Methods of using thermostable serine proteases are described herein.

Herein is disclosed a process for effectively precipitating phytase as a complex with a polyanion, as well as compositions comprising phytase and a polyanion, and a method for manufacturing such compositions.

Engineered robust high Tm-phytase clade polypeptides and fragments thereof are described herein. Also described are methods of making such engineered robust high Tm-phytase clade and fragments thereof and use thereof in enhancing animal performance.

Engineered robust high Tm-phytase clade polypeptides and fragments thereof are described herein. Also described are methods of making such engineered robust high Tm-phytase clade and fragments thereof and use thereof in enhancing animal performance.

The present invention relates to a fish feed or fish feed additive comprising one or more polypeptides having a phytase activity, wherein said phytase activity comprising EC: 3.1.3.26 (i.e., 4-phytase) and/or EC 3.1.3.8 (i.e., 3-phytase) and/or EC 3.1.3.72 (i.e., 5-phytase) phytase activity, wherein said phytase activity is dosed at a level which is at least 10% less than a efficient (e.g., optimal) dose of phytase activity configured for maximum fish growth response. The present invention relates to a method for reducing phosphorus secretion and/or excretion by a fish, said method comprising: administering the animal feed or animal feed additive according to any one of preceding claims.

The present invention relates to the field of genetic engineering, particularly to method for improving thermo-stability of phytase, mutant and use. The present invention introduces a series of mutations to the phytase APPAmut4, which may involve introducing disulfide bonds, reducing the free energy of unfolding, optimizing the key residues in the coevolution process, and significantly improving the thermal stability of the phytase. Among the mutants of the present invention, the optimal mutant APPAmut9 retains about 70% of its activity after being treated for 5 minutes at 100 C., while the phytase APPAmut4 has already been inactivated. Therefore, the present invention overcomes the shortcomings of the prior art and provides phytase mutants with high thermal stability suitable for wide application in fields such as energy, food, and feed.