Preliminary screening, isolation and identification of microbial phytase producers from soil

Abstract

Phytate is a widely found form of phosphate in plant seeds that can be hydrolysed by phytase enzyme to release phosphate and myo-inositol intermediates. Phytase has been mainly used in feed and aquaculture to reduce the anti-nutritional effect and eutrophication caused by phytate. The present study focused on preliminary screening, isolation and characterization of phytase producers from soil. A total of eleven soil samples were collected and screened by plate assay on phytase screening media followed by isolation of phytase producers to obtain pure cultures. Biochemical assays, 16s rDNA restriction fragment length polymorphism and 16s rDNA sequencing were performed for identification of phytase producers. The intracellular and extracellular phytase activity was measured by a modified Heinonen method at pH 2.5, 5.0 and 7.5. The activity of bacterial phytase producers (PSD5TSB, CD5, VD5 FD5O, FD2 and FD5T) was compared with the wild type Escherichia coli phytase. The optimum pH for enzyme activity from the soil isolates was observed at pH 5. From soil samples from eleven different sources, presence of bacterial phytase producers was confirmed in four soil samples by this preliminary screening method. The simple plate screening and activity assay helped in isolating phytase producers from soil, which can be used as potential candidates for phytase production.