baterial grew on plates but not in liquid culture

[Paul N Hengen]

Wei Shao (shaow at FCRFV1.NCIFCRF.GOV) wrote:

> I am trying to express a viral protease in E.coli. The gene is cloned 
> into pET24.  I transformed BL21 (DE3) with the contruct. The E.coli 
> grew fine on plates with Kanamycine or Kanamycine plus glucose. But, 
> when I tried to grow it in liquid medium with same kanamycine or 
> kanamycine plus glucose. It did not grow. Then, I transformed 
> DH5alpha with it. It grew fine. This seem suggest that the protein is 
> toxic (it is a protease anyway).  What I do not understand is why 
> transformed BL21 grew on plate, but not in liguid culture?  any 
> suggestions?

BL21 is a sick puppy to begin with! I've many problems with this strain.

> Also, I am thinking to use Novagen's plys system to get tighter 
> control. Any other suggestions?

Have look at the vectors in this reference....They're free :-)

@article{Mertens1995,
author = "N. Mertens
     and E. Remaut
     and W. Fiers",
title = "Tight transcriptional control mechanism ensures
stable high--level expression from {T7} promoter--based
expression plasmids",
journal = "Bio/Technology",
volume = "13",
pages = "175-179",
month = "feb",
comment = "lambda attenuated regulation at PL;nico at lmbl.rug.ac.be",
year = "1995"}

--
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