Vector pBR223-3 is reported as high expression vector having tac promoter. In this study linear pK223-3 was ligated with multiple cloning site of pUC19 cut at EcoRI and Hind III sites in order to recircularize it. Both vector and insert were double digested with enzymes, ligated, transformed and checked for the circular vector. Resulting Plasmid pKK223N was circular 4.5 Kb in size having tac promoter having two antibiotic resistant gene ampicillin and tetracycline
