Is the time constant after electroporation important for the succes of the experiment?
Very much! With our settings (0.1 cm cuvette, 1.75 kV, 25 μF, 200 ohms) we usually get a time constant around 4 ms (3.6- 4.6). With a low time constant, e.g. 2.5 ms, the discharge happen too quickly, and the bacteria are killed instead of being porated. This is probably caused by to little resistance in the media – for instance if residual salt is present. Residual salt could have come from the DNA (you should always dissolve the DNA is ddH2O) or from the washing steps in making the bacteria competent.
