Hello, I'm trying to make electrocompetent bacteria and store them at -20 degrees as I don't have -80 freezers. Is there any protocol? Should I use 50% glycerol?
Storage of bacteria is always done in the presence of glycerol (at a final concentration ranging from 10 to 20%). Storage at -20° C can work, but only for short periods of time, you should periodically check vitality of your competent cells to assess how long you can store them without harm.