Purification and properties of fungal phytase and its evaluation in broiler chicken

Abstract

Phosphorus is an indispensable prerequisite for vitality of all animals. In plants, it exists as phytate. Digestibility of phytate to monogastric organisms are limited due to lack of intrinsic enzyme that promotes the hydrolysis of phytate to free inorganic form that can be readily assimilated by them. In addition, chelation of phytate with essential dietary elements like Mg, Ca, Zn, K, Fe and Cu makes in an anti-nutrient. This approach also stimulates the algal blooms and eutrophication in water bodies due to high phosphorus content in excreta. The increased eco-friendly drive and legislations levied on environmental pollution have promoted a more scientific approach of incorporating an exogenous phytase enzyme to animal feed. Phytase is a high molecular weight phosphatase enzyme that catalyses the hydrolysis of phytate to myo inositol and inorganic phosphate, thereby enabling better digestibility and growth of animals. Microbial phytases offer techno economic feasibility for production and its application. In the urge to discover an ideal phytase with augmented properties, it remains inevitable to explore newer strains. newlineIn the present study, fungal strains from soil were screened for phytase activity in an enriched phytase screening medium. A novel fungal strain Aspergillus foetidus MTCC 11682 was screened from Brahmagiri soil and deposited in the culture repository, Microbial Type Culture Collection, Chandigarh, India. An activity of 13 FTU/mL was obtained by quantitative screening. Physical and nutritional parameters were optimized based on classical method. Optimization augmented phytase activity by two fold. Optimum phytase activity was recorded on 6th day with optimum pH of 3.5, temperature of 30°C at 5% inoculum. Lactose and sodium nitrate were the preferred carbon and nitrogen source. K++, Mg++, Mn++ and Fe++ supported phytase production. Triton X 100 induced phytase secretion by A. foetidus 11682. Immobilization of fungal spores on polyurethane foam by adsorption resulted in an increased yield of 25%. Scale up fermentation resulted in an activity of 52.7 FTU/mL with 10th day as one cycle for the batch fermentation. Immobilized fungal phytase exhibited enhanced physiochemical stability and shelf life for a period of 1 year. This study concludes that the enzyme produced from novel strain Aspergillus foetidus MTCC 11682 is a potent phytase enzyme with enhanced physio-chemical stability. It has a significant role in curbing the phosphorus menace by curtailing its excretion into soil by poultry. This phytase has the potential in animal feed application. An efficient and economic alternative for continuous production was developed. Production of recombinant enzyme in other heterogenous host, adaptation to immobilization and glycosylation are the key factors that needs to be exploited to engineer an ideal phytase. newline