Characteristics and multifarious potential applications of HAP phytase of the unconventional yeast Pichia anomala

Abstract

Most of cereal and legume seeds and their products contain 1-2% phytic acid that represents around 60% of the total phosphorus content. A large portion of phytic acid in seeds is in the form of salts known as phytates. The phytic acid-bound phosphorus (myoinositol 1,2,3,4,5, 6-hexakis dihydrogen phosphate) is poorly available to monogastrics. Therefore, inorganic phosphorus (Pi), a non-renewable mineral, is supplemented in diets for swine, poultry and fish to meet their Pi requirement. Furthermore, the unutilized phytate P from plant-based feeds is excreted, which becomes an environmental pollutant in the areas of intensive animal rearing. The excess P in soils flows into lakes and the sea that causes eutrophication, leading to water blooms and death of aquatic animals. The high negative charge on phytic acid results in the chelation of positively charged divalent metal ions (e.g. Fe2+, Ca2+, Zn2+, Cu2+, Mg2+, Mn2+) of nutritional significance, rendering a poor absorption and thus unavailable. This is partly attributed to the widespread human nutritional deficiencies of calcium, iron and zinc in developing countries where plant-based diets are predominantly consumed. The challenges in three areas of animal nutrition, environmental protection and human health justify research on phytases from different microbial sources for minimizing anti-nutritional effects of phytates and to enhance growth by improving phosphorus assimilation. This chapter reviews the developments on the production, characteristics and multifarious potential applications of phytase of the unconventional yeast Pichia anomala.