Phytate is the principle storage form of phosphorus in plants particularly in cereal grains and legumes. Mono-gastric animals doesn’t have ability to utilize phytate as phosphorus source. The animals release the undigested phytate from body with manure that cause environmental pollution. Phytases are responsible for the hydrolysis of phytate, resulting in availability of free phosphorus for the animal. The present study deals with the production and characterization of recombinant thermostable phytase and its biological evaluation in the broiler chicks. The PCR resulted in the amplification of 1.8 kb phytase gene using the genomic DNA of Thermotoga naphthophila as template. The purified PCR product was ligated in pTZ57R/T and the ligated material was utilized for the transformation of E.coli DH5α cells. The positive clones were selected on the basis of blue white screening. The restriction digestion of plasmid DNA from positive clones using NdeI and Hind III resulted in the release insert from the vector. The purified phytase gene after restriction digestion was ligated into pET21a already restricted with the same restriction enzymes and the expression was analyzed using E.coli BL21 CodonPlus (DEL) cells. SDS-PAGE demonstrated the intra-cellular production of recombinant phytase. The conditions were optimized for the optimal production of recombinant phytase (PHYTN). The maximal production of PHYTN was recorded when the BL21 CodonPlus cells having recombinant pET21a having phytase gene were induced with 1.4 mM IPTG and 6 hours post induction incubation period. The recombinant protein was purified using various chromatographic techniques and the purified protein was utilized for characterization. PHYTN showed optimal activity at 80 °C and pH 6 in sodium acetate buffer. The enzyme was found metal dependent and presence of Fe3+ or Cu2+ showed enhancing effect on PHYTN activity. Thermostability studies demonstrated that PHYTN retains 90% residual
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activity when the protein was incubated at 80 °C for 1h in the presence of 1.5 mM Fe3+. The kinetic studies of PHYTN demonstrated km and Vmax values of 50 mM and 2500 μmole/min respectively when sodium phytate was used as substrate. The characterized PHYTN was used for poultry trials to check the efficacy of the enzyme in poultry birds.
The results depicted that PHYTN put significant effect on the bird weight gain, feed intake and feed efficiency ratio. Presence of 1000 IU/kg of PHYTN resulted in the weight gain in 3rd, 4th and 5th week of trials from 504.766 to 533.535 g, 767.933 to 823.733 g and 999.833 to 1120.277 g respectively when compared with the control. The study demonstrated that this recombinant thermostable phytase is suitable for poultry feed industry and its domestic production will contribute the economic availability of PHYTN for the poultry feed industry.