transformation efficiency?

Dr. Duncan Clark Duncan at nospam.demon.co.uk
Mon Oct 11 03:46:39 EST 1999

In article <cx3M3.37467$Hb3.305617 at news.total.net>, Agata Klebucki
<agatakl at total.net> writes
>It might sound stupid, but how do I calculate the transformation efficiency
>of Escherichia coli with a plasmid.  Any help would be greatly appreciated.

Transformation efficiency is y colonies obtained per ug of plasmid.

So transform 1ng and plate 1/10 of the cells transformed. You get say
500 colonies.

Therefore transformation efficiency is 1000g/1ng x 10/1 x 500 i.e.
5x10E6 colonies per ug.

Extra competent E.coli will give say 10E8, average Calcium chloride
preps maybe 10E6. Cut/re-ligated plasmid about 1/100 - 1/1000 of uncut
supercoiled plasmid.

The problem with being on the cutting edge is that you occasionally get 
sliced from time to time....

Duncan Clark
DNAmp Ltd.
Tel: +44(0)1252376288
FAX: +44(0)8701640382

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