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Calculation of transformation efficiency

Alexander N. Kukushkin kan at mmcd.cyt.ras.spb.ru
Wed Feb 5 10:00:56 EST 1997

>   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.
You are right.

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