Phytase is a phosphatase enzyme that acts as a biological catalyst. This enzyme effectively transforms an otherwise indigestible form of phosphorus into a usable, inorganic form.
Understanding Phytate
Phytate, also known as phytic acid, is a common compound found in many plant-based foods. It serves as the primary storage form of phosphorus in seeds, grains, legumes, and nuts.
Phytate is often referred to as an “anti-nutrient” because it can bind to essential minerals. It forms insoluble complexes with positively charged minerals such as phosphorus, calcium, zinc, iron, magnesium, chromium, and manganese in the digestive tract. This binding makes these minerals unavailable for absorption by animals and humans, potentially leading to mineral deficiencies, especially in diets heavily reliant on high-phytate foods. Monogastric animals, like pigs and poultry, particularly struggle to digest the phosphorus contained within phytate, as they produce little to no natural phytase in their digestive systems.
How Phytase Functions
Phytase functions by catalyzing the hydrolysis of phytate molecules. This enzymatic action involves the stepwise removal of phosphate groups from the phytic acid molecule, releasing inorganic phosphorus.
This breakdown process makes the previously bound phosphorus and other chelated minerals, such as calcium, zinc, iron, magnesium, and manganese, accessible for absorption in the digestive tract. The efficient hydrolysis of phytate in the upper gastrointestinal tract is important for increasing the solubility and utilization of these nutrients. Different types of phytases exist, such as 3-phytase, 4-phytase, and 5-phytase, classified by their action on the inositol ring.
Major Applications of Phytase
Phytase is widely applied in animal feed, enhancing nutrient utilization and mitigating environmental concerns. In the animal feed industry, especially for monogastric animals like poultry, swine, and fish, phytase supplementation significantly improves the digestibility and absorption of phosphorus from plant-based feed ingredients. This leads to better animal growth performance, bone mineralization, and nutrient retention, reducing the need for costly inorganic phosphate supplements in their diets.
Phytase application offers environmental benefits. By increasing phosphorus utilization in animals, phytase reduces the amount of undigested phosphorus excreted in manure. This decrease in phosphorus excretion helps to lower nutrient runoff from agricultural lands, which can prevent eutrophication in waterways—a process where excessive nutrients lead to algal blooms, oxygen depletion, and harm to aquatic life. Studies have shown that phytase application can reduce phosphorus excretion by up to 50% in poultry and even 95-98% in fish.
Beyond animal agriculture, phytase also holds potential for human health and food processing. It can enhance mineral bioavailability and nutrient assimilation in plant-based food products, counteracting the anti-nutritional effects of phytic acid. This is particularly beneficial for individuals consuming plant-rich diets, such as vegetarians and vegans, or vulnerable groups like childbearing women, who may face challenges with mineral absorption. In food processing, phytase can improve the taste and properties of foods and release beneficial compounds. It has been explored for use in bread-making, where it can reduce phytate content and improve the nutritional profile of cereal products.
Sources of Phytase
Phytase is found naturally in various organisms, including animals, plants, and microorganisms. For commercial production, microbial sources are the most utilized due to their high enzymatic activity and cost-effectiveness. Fungi, such as Aspergillus niger and Trichoderma reesei, are commonly employed for large-scale phytase production. Bacteria and yeast strains also serve as sources for commercial phytase.
Microbial phytases are produced through fermentation methods, often using agricultural residues as substrates. While some plants naturally produce phytase, their activity levels are generally lower and less commercially viable compared to microbial sources. The first commercially available fungal phytase, derived from Aspergillus niger, was introduced in 1991, establishing microorganisms as the predominant source for industrial applications.