Calculation of transformation efficiency

Marieke R. Koedood Zhao rkoedood at
Tue Feb 4 13:03:59 EST 1997

That's the answer I would get too.


Kevin A. Mulcahy (K.Mulcahy at wrote:
: I have been trying to work out how to estimate transformation 
: efficiencies but in my searching through various texts I have found 3 
: different (and confusing!) ways which all give different answers!. Could 
: you please tell me if the calculation written out below is correct?

: 200µl of E. coli are transformed with 1ng of pBR322, made up to 1ml with 
: growth medium for the recovery phase and then 10µl of this plated plated 
: out (i.e. 1% of the total transformation mixture, therefore equivalent 
: to 10pg DNA used) and 100 colonies obtained. Is the transformation 
: efficiency 1 x 10(exp)7 cfu/µg DNA? (i.e. 100 colonies per 10pg DNA and 
: therefore 10,000,000 colonies per µg of DNA).

: Thanks,

: Kevin Mulcahy.

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