Competent cells at OD = 0.94

Cornelius Krasel krasel at
Thu Mar 14 09:17:23 EST 2002

Peter Ianakiev <ianakiev at> wrote:
> Any suggestions of making ultra competent (library grade) cells will be
> appreciated. Inoue method looks good, but has an  insufficient yield for
> our needs.

If you don't get the bacteria competent enough, it may help to rinse
the flasks in which you grow the bacteria with NaOH. This did the
trick for us recently when we desperately tried to get competent
cells with a method that had previously worked in the lab to get
transformation efficiencies of >1e7 (we use the method described
in CT Chung, SL Niemela, RH Miller, PNAS 86: 2172-2175 (1989)).
I suspect traces of detergent as the culprit.


/* Cornelius Krasel, U Wuerzburg, Dept. of Pharmacology, Versbacher Str. 9 */
/* D-97078 Wuerzburg, Germany   email: krasel at */
/* "Science is the game we play with God to find out what His rules are."  */

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