Phytase, i.e. phytase, is a kind of enzyme that catalyzes the hydrolysis of phytic acid and its salts into inositol and phosphate. At present, phytase is mainly used as feed additive for monogastric animals, and several phytase preparations have been commercialized. As a green feed additive, phytase can effectively improve the utilization rate of phytate phosphorus in livestock and poultry, save phosphorus resources, reduce the phosphorus content in livestock excreta, alleviate the anti-nutritional effect of phytic acid, and improve the growth and production performance of livestock and poultry. In addition, phytase also has application prospects in other fields, such as food additives, catalysts for enzymatic production of inositol phosphate drugs and soil amendments. Phytase has shown great application potential and research value in animal nutrition, resource and environmental protection and human health.
phytase is ubiquitous in plants, fungi, yeasts and bacteria, among which microbial phytase is the most widely studied and developed because of its high activity and easy production, and the phytase in Trichoderma has a long history. In 1998, Anusuya et al. studied the degradation of calcium phosphate and phosphate stone by three Trichoderma species, such as T.harzianum, T.viride and T.paseudokoningii, and compared them with Bacillus megaterium and Aspergillus awamori. The results showed that all three Trichoderma species had the ability to degrade two insoluble phosphates, and T. In 1999, Altomare et al. discovered that T.harzianum strain T22 has the ability to dissolve insoluble or slightly soluble minerals, which can dissolve metal oxides through chelating degradation, promote the absorption of minerals by plants and increase the growth of plants. In the same year, n? Si M et al. compared the differences of phytase utilization by Aspergillus Niger (Aphy) and T.ressei phytase (Tphy) in corn-soybean feed and barley-soybean feed. The feeding comparison test showed that T.reesei phytase had higher utilization ratio of phytate phosphorus in feed than Aspergillus Niger phytase and acid phosphatase. In 25, Wang Shihua, Fujian Agriculture and Forestry University, etc. isolated and mutated by nitrosoguanidine, and bred a strain T.viride LH 374. Its optimum temperature is 55℃ and its optimum pH is 6.. It has good thermal stability and acid resistance, and its phytase production can reach 158 U/g on average. Yang Contract of Shandong Academy of Sciences collected 244 soil samples from the vegetable base in Shandong Province, and the Trichoderma isolated from them basically has phosphorus solubilizing activity, and can hydrolyze calcium phytate and calcium phosphate on agar plate to form transparent hydrolysis circle. Juck Zhang et al. (212) inoculated 148 strains of Trichoderma on phytase-producing medium. After 3 days, it was observed that all strains produced hydrolysis circles. At the same time, the phytase activity of Trichoderma was detected by ferric chloride-sulfosalicylic acid method using phytic acid as substrate, which indicated that phytase production was a common property of Trichoderma.
in terms of gene, the phytase PhyA gene sequence (AJ543399.1) of T.harzianum submitted by Rey et al. can be retrieved in GenBank, which has homology with phytase from Aspergillus et al. In addition, the recent patent of T.reesei phytase (patent US 751831, GenBank: GP 287369.1) has no homology with other phytases. A patent (application No.29246856) of Genentech International Co., Ltd. in the United States mentioned that an active phytase was purified from T.reesei ATCC13631, and its DNA sequence was cloned. The amino acid sequence was 41% ~ 49% homologous to phytase from other filamentous fungi, but the amino acid sequence in the active region was highly homologous to other filamentous fungi.
Li Xiaolong et al. (21) investigated the phytase activity of 136 Trichoderma strains preserved in the laboratory, and the preliminary results showed that Trichoderma generally had phytase activity; Based on the fact that the radius of transparent circle is significantly larger than the colony radius (the difference of radii is ≥.3cm), 36 strains with high phytase activity were screened. By predicting and analyzing the structure of Trichoderma phytase obtained by cloning, it is found that Trichoderma has a potential structure with higher thermal stability and catalytic activity than Aspergillus Niger phyA in the functional structural components that affect the two important enzymatic characterization of phytase.