I am trying to generate a knockout with lambda red recombination but I lack an the equipment for electroporation and hence I am left to decide between CaCl2 cells or RbCl cells. I am wondering what is the efficiency difference between the three types of transformation techniques, in terms of actual data such as transformation efficiencies. I can't find any papers reporting on this but am wondering if anyone has done an optimization to know an estimate if it's worth going through the trouble (and cost) of RbCl cells.
For reference, I'm trying to knockout pcnB in E. coli MG1655 with pKM208.
In the past, we compared CaCl2 versus RbCl cells with respect to the efficiency of plasmid transformation. The RbCl cells worked much (10x) better (protocol according to Hanahan 1983 ( J Mol Biol. 1983 Jun 5;166(4):557-80.). It is easy to prepare these competent cells; stored at -80C they can last for a couple of years.
RbCl-treated cells are way better but their preparation is also more involved. In my opinion, unless you really need high-frequency transformation it is easier/faster to just add more DNA when using CaCl2-treated competent cells.
Hope it helps!
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