Figure 4. Effect of ompA inactivation on chemical transformation with a shortened time for heat shock.

Competent E. coli cells were prepared with CaCl₂ solution at 60 mM. The mixture of competent cells and pDsRED on ice was placed in the water bath (42°C) for 2∼30 seconds. Chemical transformation frequencies of E. coli BW25113 (solid square symbols) and JW0940 (BW25113::ompA::kan, open circle symbols) were shown. Each point denotes an average of 2 to 4 samples. Error bars denote standard deviation. ^*P value ≦ 0.05; ^**P value ≦ 0.01.