Biochemical characteristics of phytase obtained from Aspergillus niger Phy8 and its application in dephytinization of various flours

Phytic acid is considered one of the main sources of organic phosphorus which is required for growth of plants and animals. However, it strongly binds to the soil solid phase and its anti-nutritional activity in feed making phytate phosphorus unavailable to the plants and animals. Phytase is able to improve the phosphorus availability from phytate and thereby phytase production is desirable. Aspergillus niger Phy8 has capability of phytase production. The molecular mass of the purified enzyme was about 5 7KDa determined by SDS-PAGE. The purified phytase exhibited optimal pH 5.0 and optimal temperature of 50 degrees C. The enzyme showed acid stability, thermostability and broad substrate specificity, indicating a promising candidate for industrial application. The phytase activity exhibited significant inhibition by Cu2+, Mn2+, Fe2+ and Hg2+. However, K+ and Mg2+ exhibited a significant positive enhancing effect on phytase activity. N-ethylmaleimide (NEM) inhibited the enzyme activity by approximately 25%. N-bromosuccinimide (NBS), diethylpyrocarbonate (DEPC) and phenylglyoxal (PGO) with concentration of 5 mM inhibited phytase activity. The purified enzyme was significantly released the associated phytate products (soluble proteins; phosphorus; reducing sugars), representing compatibility with feed and food applications. In addition, the enzyme phytase showed dephytinization of wheat, corn and rice flours. Therefore, phytase application can improve levels of proteins and reducing sugars, result an increment in the nutritional quality of food ingredients and availability of inorganic phosphate to plants.