Preparation and Transformation Conditions for Efficient JM109 Competent Cells

Competent cells of Escherichia coli JM109 were prepared by different transformation liquid,and pUC18 was transformed into the competent cells.The effects of different growth state of bacteria,transformation liquid,heat shock time and culture medium after heat shock on transformation efficiency were studied.The results showed that the highest transformation rate could be obtained by preparing the competent cells by TB transformation liquid when bacteria A600 nm was 0.705,heat shocked at 42 ℃ for 45 s and then culturing in SOC medium.The transformation efficiency could reach to 8.59×108 CFU/μg plasmid.