PHYTASEAn Enzyme with a Huge PotentialAditya Kanwal 2012BT09 M.Tech Biotechnology MNNIT, Allahabad

INTRODUCTION:PHYTASE:A phytase (myo-inositol hexakisphosphate phosphohydrolase) is any type of phosphatase enzyme that catalyses the hydrolysis of phytic acid (myoinositol hexakisphosphate) --an indigestible, organic form of phosphorus that is found in grains and oil seeds and releases a usable form of inorganic phosphorus.

SUBSTRATE:PHYTIC ACID:- Phytic acid (phytate when in salt form) is the principal storage form of phosphorus in many plant tissues, serving its role as a phosphorus store, as an energy store, as a source of cations and as a source of myoinositol (a cell wall precursor).

- Phytate is not digestible to humans or nonruminant animals, however, so it is not a source of either inositol or phosphate if eaten directly. -As it is released undigested, it can contribute to eutrophication of surface water and algal blooms.

- Moreover, it chelates and thus makes unabsorbable certain important minerals such as zinc, iron, manganese and magnesium. -Also prevents absorption of certain biomolecules like proteins and starch.

- Ruminant animals, can use phytic acid as a source of phosphorus because the bacteria that inhabit their gut are well characterized producers of many types of phytases.

TYPES OF PHYTASES:1. Histidine acid phosphatases (HAPs): - HAPs have been isolated from filamentous fungi, bacteria, yeast, and plants. - All members of this class of phytase share a common active site sequence motif (Arg-His-Gly-X-Arg-X-Pro)

2. -propeller phytases: - The three-dimensional structure of -propeller phytase is similar to a propeller with six blades. - Current research suggests that -propeller phytases are the major phytatedegrading enzymes in water and soil, and may play a major role in phytatephosphorus cycling.

3. Purple acid phosphatases: - Isolated from the cotyledons of germinating soybeans that has the active site motif of a purple acid phosphatase (PAP). - Searches of genomic databases has revealed PAP-like sequences in plants, mammals, fungi, and bacteria

4. Protein tyrosine phosphatase-like phytases: - Only a few of the known phytases belong to this superfamily. - All characterized PTP-like phytases share an active site sequence motif (HisCys-(X)5-Arg)

METHODS OF EMPLYOMENT:- The phytase from the fungus Aspergillus niger is a HAP and is well known for its high specific activity and its commercially marketed role as an animal feed additive. Phytase can also be isolated from Basidiomycetes fungi. Various Bacteria have also been shown to release Phytases in large amounts like in Stretptomyces and Lactobacillus sp. - Phytases have also been over expressed in several transgenic plants as a potential alternative method of phytase production for the animal feed industry. Phytases have been recently produced in transgenic canola, alfalfa and rice plants. - Recently, the phytase gene from E. coli has been successfully expressed in the salivary glands of a transgenic pig.

APPLICATIONS:APPLICATION Phytases as feed additives. MAIN EFFECT Increased P utilisation and metal bioavailability; decreased P concentration in excrements. Increased P availability; decreased P pollution in water bodies. DESIRED PROPERTIES Resistance to low pH, peptidases and high temperatures. Resistance to Physiochemical changes during the remediation process; capacity to utilize recalcitrant P forms. P liberation should be greater than the P requirement.

Inoculation of inorganic residues with phytase producing Bacteria for bioremediation.

Inoculation of roots with Increased uptake of P in phytase producing organic forms by plants. Bacteria.

Improvement of mineral Increased uptake of mineral Resistance to low pH, nutrition in Humans. ions especially iron, zinc and peptidases and high calcium. temperatures.

PHYTASE MARKET- Present global phytase market is valued by experts at about USD 350-500 million and growing at a rate of 5 % per annum. - The US and China are the key markets for feed phosphates, a vital feed additive for healthy and strong animals. - At present most of the enzyme products in India are directly imported or the individual enzymes are imported and formulated. These enzymes attract import duty, making their usage expensive. - A very few companies produce Phytase in India like Biocon and MAPS enzymes. DBT, DST and other funding agencies have been trying to solve this problem of phytase shortage in the country.

A CASE STUDYPhytase in Swine Diet: - Studies have indicated that the inclusion of phytase in swine diets has increased the availability of phytate phosphorus in a cornsoy diet from approximately 15% to 45%. [Phytase activity is expressed as "phytase units" or "FTU" per unit of feed]

- The inclusion rate for phytase in all stages of swine diets is 115 to 227 FTU/lb. -Calcium should be reduced approximately 10% to maintain the proper calcium:phosphorus ratio.

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