Production of fungal phytases in solid state fermentation and potential biotechnological applications

Phytases are important enzymes used for eliminating the anti-nutritional properties of phytic acid in food and feed ingredients. Phytic acid is major form of organic phosphorus stored during seed setting. Monogastric animals cannot utilize this phytate-phosphorus due to lack of necessary enzymes. Therefore, phytic acid excretion is responsible for mineral deficiency and phosphorus pollution. Phytases have been reported from diverse microorganisms, however, fungal phytases are preferred due to their unique properties. Aspergillus species are the predominant producers of phytases and have been explored widely as compared to other fungi. Solid-state fermentation has been studied as an economical process for the production of phytases to utilize various agro-industrial residues. Mixed substrate fermentation has also been reported for the production of phytases. Physical and chemical parameters including pH, temperature, and concentrations of media components have significantly affected the production of phytases in solid state fermentation. Fungi produced high levels of phytases in solid state fermentation utilizing economical substrates. Optimization of culture conditions using different approaches has significantly improved the production of phytases. Fungal phytases are histidine acid phosphatases exhibiting broad substrate specificity, are relatively thermostable and protease-resistant. These phytases have been found effective in dephytinization of food and feed samples with concomitant liberation of minerals, sugars and soluble proteins. Additionally, they have improved the growth of plants by increasing the availability of phosphorus and other minerals. Furthermore, phytases from fungi have played an important roles in bread making, semi-synthesis of peroxidase, biofuel production, production of myo-inositol phosphates and management of environmental pollution. This review article describes the production of fungal phytases in solid state fermentation and their biotechnological applications.