Background & Objectives: Phytate is the primary storage form of phosphorus in plant seeds. It has an anti-nutritive effect in both human and animals. Phytase is a subgroup of phosphatases which catalyzes the hydrolysis of phytate. Microbial phytases have potential biotechnological application in various fields, such as agriculture, human and animal foods. This study was aimed to investigate the optimal conditions for the production of phytase by Bacillus subtilis isolated from the soil. Materials & Methods: Samples were collected from Arak area, where the soil was contaminated with animal faces. Samples were incubated in PSM medium at 30 ºC for 48 hours. The screening of phytase - producing bacteria on PSM media was performed based on the formation of the clear halo. The most suitable bacterial strain was identified according to its biochemical and morphological characteristics. The level of enzyme production and phosphate- solubilising activity of this strain was assessed in different pH range, and on various media types including PSM, PVK, NBRIP, as well as NBRIY. Results: In this study, maximum enzyme production by the bacterial isolates has been observed following 36-48h incubation in PSM medium. 12S phytase- producing bacterial strain was identified as Bacillus subtilis. Our results showed that the optimum pH for phytase production in PSM medium is pH of 7. Furthermore, investigating different media, phytate-containing PVK was recognised as the most appropriate medium for enzyme production. Conclusion: B. Subtilise isolate can provide an opportunity to introduce new phytase to food as well as environmental industries. Moreover, PVK can be used as an effective medium to produce phytase enzyme and to screen phytase-producing bacterial starins.
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