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Glycerol wash protocol for chemical competent cells - (Mar/15/2006 )

First thank you all for so much useful information. I didn't have a clue about electro vs chemical competent cells which I believe it is quite important.

Fred said he was successfully using the glycerol wasking protocol.Other post said that CsCl2 protocol doesn't work well with electrocompetent cells. My question is:
Can I use the simple protocol with glycerol described by Fred with chemical competent cells (JM109 in my case)? If it does work with electrocompetent cells, why shouldn't it work with chemical competent cells?

Another question is: Do you think it is really important to select JM109 on M9 Minimal media containing thiamine? (Promega says is to retain the F' episome for White/Blue screening).


well actually, the glycerol washes is one s=of he process that makes the electric cometitivity of the cells. And CaCl2 washes makes the chemical competitivity. So i would not intervert the two protocols.