Production of Taq DNA polymerase In our laboratory the encoding DNA of Taq polymerase enzyme was cloned and placed in the pET15b expression vector to obtain large amounts of Taq DNA polymerase 171 Production of Taq DNA polymerase in Escherichia coli BL21(DE3) cells was induced by incubation with isopropyl OPTG). SDS-PAGE analysis of cell extract showed a prominent polypeptide band of the expected molecular mass[Figure 1, lane 2l and the recombinant Tau DNA. polymerase was purified according to Desi Method[Figure 1, lane 30. The activity of the obtained enzyme was measured by comparing the intensities of the produced DNA bands in PCR reactions. Results well showed an obtained active and stable enzyme which could be used in our laboratory for PCR reactions. Finally, produced recombinant enzyme was added t home-made master mix for the next step.