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How much plasmid for transformation? - (Mar/15/2007 )

I simply want to transform my plasmid into E. coli cells by heat shock.
My question is how much of the plasmid should I use for this transformation .
Thank you for your answers.



u can use a concentration of 50 ng to 100 ng.


-madhan shankar-

Normally, I use 10-50 ng of my plasmid for transformation to E.Coli. The maximum volume that can be used in the transformation is ~10% of your total volume. Amounts of DNA can differ for different E.Coli cells.

For commercial available competent E.Coli you can use less DNA than for home-made competent cells. (and for the commercial available, the amount of DNA/plasmid is mentioned in the protocol)




If you are retransforming a plasmid, you could use very less DNA, 1 ng or even less. I have tried upto 100 pg for tranfsormation.


I serially diluted a plasmid prep (800ng/uL) to see how little DNA I could get away with. 800pg gave me heaps of colonies, I got about 3 with 8pg. But for a ligation, you might need a bit more because most of the DNA present probably won't be the correct construct.