Plasmid size limit for transformation

David L. Haviland, Ph.D. dhavilan at IMM2.IMM.UTH.TMC.EDU
Thu Oct 16 12:55:51 EST 1997

At 17:02 10/16/97 GMT, Torben =AFsterlund wrote:
>I am about to make a construct that will be approx. 21 kb (including the
>2.9 kb of the vector, pBluescript).
>My question is: will it be possible to transform E. Coli with this
>(monster) plasmid  by electroporation?. Should I adopt some special
> Thanks for your tips!


If the construct is intact, it will be hard, but you can get it in and
electroporation is likely to be your only viable choice.

Just for fun, I prepped XL-1 mrf' for electroporation and took 10 ng of
various purified plasmids that I had and tested the efficiency.  With
bluescript and pUC19 both were just short of 10^8 (actually high 10^7
cfu/ug), with the old BlueBacIII (10.5kb), the efficiency dropped off to
the low 10^4 cfu/ug.  Finally, when I tried an intact cosmid (40-45kb), it
dropped further down into the low 10^3 cfu/ug.  So in short, it's do-able,
but you may have to struggle with it.

Hope this helps,

More information about the Methods mailing list