electroporation food for thought

jim jgraham at bronze.ucs.indiana.edu
Fri Dec 13 14:22:57 EST 1991

Thanks to every one for sending me electroporation comments. If you ask I'll 
forward the set to you.

I was just thinking, typically in preparing E. coli cells for electroporation, the
culture is concentrated 500 to 1000 fold before zapping. In most standard Ca
procedures, the cells are grown to about half the corresponding density, and 
concentrated about 40 fold (say 50). For the same volume of cell preparation then,
there are 20 to 40 times more cells in the electroporation procedure. The gist of
the discussion was that electroporation gives about 100 fold better cfu/mcg DNA
than standard Ca procedures. Perhaps that should be (per cell) only about 2 or 3
fold better.

Of course who's to say that Ca procedures would work with concentrated cell
suspensions. However, washing a litre culture and resuspending in 1 or 2 ml is
a royal pain in the ass. 

Also, everyone I've seen tends to overreport (not you guys :) though ) thier
Ca tranformation efficiencies (ie. if I had only used 2 ng.....). Realistically
I've only measured a million to ten million cfu/mcg DNA.

jgraham at bronze.ucs.indian.edu

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