Transformation Efficiency

Dima Klenchin klenchin at facstaff.REMOVE_TO_REPLY.wisc.edu
Thu Mar 18 13:43:59 EST 1999

:Hi all,
:I am transforming CaCl competent cells and would be grateful if anyone could
: tell me, or 
:point me in the right direction on, how to calculate the transformation
: efficiency of my 
:cells. I am/may be foced to blunt end ligate and therefore want cells with a
: high 
:transformation efficiency. Our copy of Current Protocols in Molecular Biology
: is missing 
:the vital pages.

You have used, say, 10 ng of DNA per tube. After dilution with medium and 
growth for one hour you have, say, 1 ml. You plated 50 ul of this on the 
plate. You've got, say, 100 colonies. The transformation efficiency is
how much colonies you would get if you'd used 1 ug DNA and plated all 
your transformed bacteria (for this calculation it is assumed that 
dependence on [DNA] is linear, which is generally incorrect)

In the above example it is 100*20/0.01=2*10^5/ug

- Dima

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