Co-transformation of Plasmids by Efficient CaCl_2 Transformation

An efficient procedure for the preparation of competent cells and CaCl_2 transformation was established by improving routine methods in order to increase co-transformation efficiency.The transformation efficiency of this method reaches to 10~8-10~9 transformants/μg DNA.It could meet the requirements of all kinds of transformation experiments.Two foreign vectors including a donor plasmid and a receiver plasmid were co-transformed into a Cre-strain using this method.Restriction digestion showed that hIGF-1 gene of donor plasmid had been ligated to specific site of receiver plasmid by site-specific recombination mediated by Cre enzyme.