Study on the Transforming Efficiency of Escherichia coli and Agrobacterium Transformed by Different Methods

Plasmid pBI121 was transformed into Escherichia coli by freeze-thaw method and heat-shock method,and into Agrobacterium using freeze-thaw method.By Gus assay and electrophoresis detection,Escherichia coli DH5α,JM109,and Agrobacterium EHA105,LBA4404,we got the plasmid pBI121.Meanwhile,the main factors influencing transformation efficiency of E.coli and Agrobacterium were discussed.Results showed that E.coli competent cells got high transformation efficiency stored at 4℃ for 18h.Competent cells stored with glycerin at low temperature for 20d could be transformed,but the transformation efficiency was lower.Transformation efficiency of Agrobacterium was higher when OD600 was from 0.45 to 0.65.