cloning and expression of thermus aquaticus dna polymerase gene, using a thermo-inducible expression vector

dna polymerase gene from thermus aquaticus strain yt1 was amplified using venttm dna po-lymerase and cloned under the control of x.pr promoter and expression was induced by a shift in tern perature. the culture was then sonicated, and after centrifugation the lysate was treated with poly ethyleneimine followed by a salting-out step. finally the protein was precipitated with ammonium sulfate and fractionated by gel filtration. the resulting enzyme preparation was stable and active.