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The aim of this study is to evaluate the transformation efficiency and practicality of the direct transformation method, transformation competent cells E. coli DH5 α with pUC19 plasmid with only mixture of competent cells and plasmid. The experimental groups were as follows; Group 1, after competent cells was mixed with pUC19 plasmid, the transformation mixture was immediately plated onto ampicillin (100 ㎍/ml)-LB agar plate; Group 2, after the transformarion mixture was placed on ice for 20 min, that was plated onto ampicillin (100 ㎍/ml)-LB agar plate after; Group 3, after the transformation mixture was heat-shocked at 42℃ for 1 min and then place on ice fot 2 min, that was plated onto ampilcillin (100 ㎍/ml)-LB agar plate; Group 4, after the transformation mixture was heat-shocked, added 200㎕ of LB broth and then incubated at 37℃ shaking incubator for 1 hr, that was plated onto ampicillin (100 ㎍/ml)-LB agar plate. Our data revealed that the transformation efficiency of Group 1 was the same as that of Group2, 2-folds lower than that of Group 3 and 8-fold lower than that of Group 4. Even though, the transformation efficiency of Group 1 was lower than that of Group 3 or 4. it is sufficient transformation efficiency to clone a plasmid vector. Therefore, the direct transformation method may be useful in cloning of a plasmid vector.
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