1. Heat-kill ligation reaction at 65 deg C for 10 min (increases transformation efficiency by 40-fold)

2. thaw tube of 50 ul electrocompetent cells on ice, keep on ice once thawed.

3. Mix DNA and cells on ice and transfer the mix to prechilled sterile electroporation cuvette. Use 1 ul of ligation mix (undiluted) and 50 ul of electrocompetent cells.

4. Electroporate using BioRad Genepulser set to 2500 Volts.

5. Following electroporation, immediately! add 500 ul of SOC medium directly to the cuvette and resuspend the cells by pumping up and down a few times with a P1000 pipetman.

6. Transfer the cell suspension to a 15 ml sterile culture tube and place in 37 deg shaker incubator and shake for 30 min.

7. Plate on an agar plate with selection antibiotic, use a sterile spreader. Note if you are transforming with ligation mix, use the entire cell suspension, but if you are transforming with intact plasmid say from a miniprep, use only 20-50 ul of the cell suspension on the plate otherwise you will have a lawn of bacteria without individual colonies.

SOC medium: 2% Bacto-tryptone, 0.5% Bacto yeast, 10 mM NaCl, 2.5 mM KCl