Optimization of catalytic activity of phytase from isolate K46b using response surface methodology

Phytases (myo-inositol 1,2,3,4,5,6 hexakis phospho-hydrolase), found in plants, animal tissues and microorganisms, are a group of phosphatases capable of hydrolyzing phytic acid, the most abundant inositiol phosphate in nature, to myo-inositol and inorganic phosphates. In this study, 68 microbial isolates from different sources were screened using submerged fermentation for the best phytase production. The results showed that isolate K46b had the highest phytase production (1.952 U/mL) among other isolates. Subsequently, the catalytic activity of phytase enzyme of isolate K46b at different conditions of temperature, pH and sodium phytate concentration was optimized using response surface methodology (RSM). Under optimum conditions i.e. 56.5 ºC, pH 7.30 and 2.05 mM sodium phytate, the phytase activity increased to 4.627 U/mL which compared to the screening step, it showed a 137% increase. Moreover, the phytase showed 60-73% of its optimum activity in wide ranges of temperature (47-68 ºC), pH (6.3-8.0) and sodium phytate (1.04-2.50 mM). It can be concluded that isolate K46b phytase has potential applications in dephytinization of food ingredients such as cereals and meals in in food and animal feed industries, aquaculture and combating phosphorous pollution in the environment.