Masoud Mohammadirtment,Mehrdad Azin, Mahsa Sedighi
Biological Journal of Microorganism, Year 6th, No. 23, Autumn 2017

 Phytase can be used as a feed additive to catalyze the hydrolytic degradation of phytate as the major storage form of natural phosphorus. Phytase is produced by a wide range of bacteria, fungi and yeasts. Isolation and identification of phytase-producing strains from soil, is of great interest for commercial application in different industries. The aim of the current study was the isolation and identification of phytase-producing strains from soil samples and optimizing the enzyme production.
Materials and methods:
For isolation and identification of phytase-producing strains, soil samples were collected from farms near Qazvin. Diluted samples were spread onto PSM solid media and production of the clear zones about the colonies gave a visual indication of phytase production. The selection of the best phytase-producing strain was performed by measuring the enzyme activity in the liquid medium. The selected strain was identified by slide culture technique and the effect of carbon source (phytate and wheat bran), pH and time of incubation were also investigated for optimal enzyme production.
 In this study, a Penicillium sp. was isolated from a soil sample near Qazvin and was selected as the best phytase-producing strain. The maximum phytase activity (171 U/ml) was obtained in the medium containing % 2 (w/v) phytate, at pH 5, after 72 h of incubation. By using wheat bran as the source of carbon and phytate, the maximum phytase activity, which was 61.7 U/mL, was produced at pH 7 and after the same time of incubation.
Discussion and conclusion:
 Penicillium sp. isolated from a soil sample near Qazvin, was able to produce highly active phytase in optimized environmental conditions, which could be a suitable candidate for commercial production of phytase to be used as complement in poultry feeding industries

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