E. Coli Transformation

"Marianne Leverone ", BIO leverone at CHUMA.CAS.USF.EDU
Thu Oct 19 12:25:49 EST 1995

Quim:  I bet you had Pseudomonas aeruginosa.  If the bizarre odor smelled 
like Welch's grape juice, that's what you had.  Marianne Leverone, 
Biology, Univ. of South Florida, Tampa, FL

On 18 Oct 1995, Joaquim Culi wrote:

> I've got the same problem and finally I've located the source of 
> bacterial contamination in the water of the bath. My contaminant cells
> were green and they had also a bizarre odor. I suggest you to examine the
> contaminant colonies under a microscope to check if they are E. coli or
> another thing.
> Hope this help.
> Quim. 
> In article <rocco-1810950828400001 at haarerlab.zo.utexas.edu>,
> rocco at mail.utexas.edu (Stephen J. Palmieri) wrote:
> >       I've got the weirdest problem known to mankind concerning my
> > transformation.  I've got some sort of bacterial contamination that will
> > not go away.  If  I plate untransformed cells(doesnot matter which strain)
> > on an LB/Amp plate, nothing grows. But if I transform a ligation reaction
> > I get these colonies containing no plasmid DNA and have a really bizzare
> > odor and look in liquid culture.  If I transform a covalently closed
> > plasmid about 80-90% of the colonies contain plasmid DNA so it is not a
> > matter of degredation in my minipreps.  I've been using XL1-Blue and SURE
> > cells because they grow very slow and I can tell a true transformant from
> > a contaminating colony.  I've sterilized everything I could think of
> > including changing my source of ddH2O  and increasing the Amp
> > concentration to 100ug/ml.  Can someone out there please tell me what the
> > hell is going on?  Anything would be much appreciated.
> > 
> >                            Steve Palmieri

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