Phytase

Phytase refers to any enzyme that catalyzes the hydrolysis of phytic acid (myo-inositol hexakisphosphate) – an indigestible organic form of phosphorus that is found in many plant tissues, especially bran and seeds. The enzymatic reaction releases inorganic phosphate from phytic acid, as well as inositol.

Function and Importance:

Phytase is crucial for improving the nutritional value of plant-based diets for humans and animals. Phytic acid strongly binds to essential minerals such as calcium, iron, zinc, and magnesium, making them unavailable for absorption. By breaking down phytic acid, phytase increases the bioavailability of these minerals and reduces the excretion of phosphorus in manure. This latter benefit is particularly important in animal agriculture, as high levels of phosphorus in manure can contribute to environmental pollution of waterways.

Sources and Applications:

Phytases are produced by a variety of microorganisms, plants, and some animal tissues. Commercially, phytases are produced by microorganisms like Aspergillus niger, Escherichia coli, and Pichia pastoris through fermentation. These commercially produced phytases are widely used as feed additives in livestock diets, particularly for poultry and swine, to enhance phosphorus utilization and reduce the need for inorganic phosphorus supplementation. They are also being explored for potential applications in human food processing to improve mineral bioavailability and reduce the anti-nutritional effects of phytates. Phytase can also be used in various industrial applications related to the hydrolysis of phytates.

Types of Phytases:

Phytases are classified based on their substrate specificity and optimal pH. Different types include:

• 3-phytases: Hydrolyze phosphate from the 3-position of the inositol ring.
• 6-phytases: Hydrolyze phosphate from the 6-position of the inositol ring.

Other classifications are based on their amino acid sequence and catalytic mechanism.

Regulation:

Phytase activity is influenced by various factors, including pH, temperature, and the presence of inhibitors or activators. Understanding these factors is crucial for optimizing the use of phytase in different applications.