E.coli transformation protocol wanted

Paul N Hengen pnh at fcsparc6.ncifcrf.gov
Tue Aug 23 16:22:10 EST 1994


 In article <zjons-200894131315 at 130.60.120.10>
 zjons at vetbio.unizh.ch (Zophonias O. Jonsson) writes:

> ...I plated 200 ul and got 26 transformants.  That's not
> so swell, about an order of magnitude lower than I usually get when I catch
> the cells at 0.4, but still O.K. for most purposes.
.
- >% snip -
.
> I would like to hear if others have had better luck with this than I did.
> If this works well for others I just might try again.

When I saw this paper, I had doubts about how it was done. I immediately thought
that the different people (look at the paper -> it took nine authors to do
a simple transformation) who did the experiments could have done something very
different when plating, thus causing the different numbers of transformants.
Why would the competency of cells change so dramatically over a very short
period of growth??? From what you said, it makes me think there is a very small
window...but why?

BTW, the paper I'm referring to is:

@article{Tang1994,
author = "X. Tang
     and Y. Nakata
     and H.-O. Li
     and M. Zhang
     and H. Gao
     and A. Fujita
     and O. Sakatsume
     and T. Ohta
     and K. Yokoyama",
title = "The optimization of preparations of competent
cells for transformation of {{\em E. coli\/}}",
journal = "Nucl. Acids Res.",
volume = "22",
number = "4",
pages = "2857-2858",
comment = "1x10^8 transformants per ug DNA at O.D. 0.94",
year = "1994"}

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