To maximise protein expression, fresh transformants are strongly recommended !

• Thaw an aliquot of competent cells on ice (for up to 15 minutes).

• Add 10-50 ng of DNA to a 50 µl aliquot of the cells.

• Mix the cells and DNA by gently flipping the tube.

• Incubate the tube on ice for about 20 minutes.

• Place the tube at 42°C for 2 minutes, then put it back on ice for 3 minutes.

• Add 400 µl of LB medium and incubate the tube for between 15 minutes at 37°C.

• Spread a drop (up to 100µl) of bacteria on LB-agar Petri plates containing the appropriate antibiotic.

• Incubate the Petri plates at 37°C for 20±4 hours.