EFFECT OF PLASMID SIZE ON THE TRANSFORMATION OF E.COLI HB101

Plasmids are one of the most common vectors used in cloning. Many factors have been repotted to affect the bacterial transformation by plasmids. This paper an attempt to find the effect of plasmid size on the transformation efficiency of E.coli HB101. Our results showed that the small sized Plasmids more effective in transforming of the bacteria E.coli HBCOL was) (4.1-4.8kb than the large ones (5.7-6kb). The transformation efficiency with the small sized plasmids reaches between 6×610-7×610 comparing with 4.1 ×105- 4.6×105 of the large sized plasmid. We conclude that the small sized plasmids are more suitable to use in cloning than large sized plasmids.