|Surface / ribbon model of the 3-phytase from Aspergillus niger . The amino acids His-59 and Asp-339, which form the catalytic center, are shown as domes (according to PDB 1IHP )|
|Gene name (s)||phy|
|EC, category||188.8.131.52 , phosphatase|
|Substrate||myo -inositol hexakisphosphate + H 2 O|
|Products||myo -inositol pentakis phosphate + phosphate|
Phytase is the name of a group of enzymes that hydrolytically break down phytic acid and thus release the bound phosphate. Of course, phytases occur in a number of plants and microorganisms, including in the germ and bran of cereal grains, but also in bacteria that live in symbiosis with ruminants . Phytases make the phosphorus bound in plant seeds available as an energy reserve and are therefore increasingly being added to commercial animal feed.
Depending on which phosphate group is broken down, a distinction is made between 3-, 4-, 5- and 6-phytase. The phytase formed by many plants and bacteria functions as 3-phytase ( EC 184.108.40.206 ); this is used commercially together with 6-phytase ( EC 220.127.116.11 ). 4-phytase is an acidic phosphatase ( EC 18.104.22.168 ) and not much is known about 5-phytase ( EC 22.214.171.124 ). The latter is able to split off further phosphate up to inositol triphosphate .
Phytase is mainly used in the animal feed industry as an additive in feed to break down the phytic acid found in plants and to make the phosphate it contains available. This is especially necessary when feeding non- ruminants such as poultry and pigs , since otherwise the phosphate naturally contained in the plant-based food passes through the intestines unused and is released into the manure . The use of phytase can reduce the addition of inorganic phosphate in the feed. The better recycling also reduces the wastewater pollution from excreted phosphate in the manure and in the stable manure.
Phytase is mainly obtained biotechnologically by fermenting granulated sugar or alternative substrates, especially starch . Genetically modified fungal cultures such as Aspergillus and Trichoderma species and fission yeast ( Schizosaccharomyces pombe ) are used as organisms .