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