E. Coli Transformation

David L. Haviland, Ph.D. haviland at KIDS.WUSTL.EDU
Thu Oct 19 15:49:00 EST 1995


On Wed, 18 Oct 1995, 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
		*SNIP*

A couple of odd thoughts.  
Have you streaked your host cells on LN-tet plates?  More often than not, 
this selects the bugs you want and kills most anything else.

Second,  HOW does the culture look in suspension?  If you have stringy 
stuff then under the heading of "been there, done that" you may be doing 
battle with a concurrent phage infection of some kind.  We had a phage 
infection of a plasmid stock and two tell tale signs was that plasmid 
yeilds kept going down with successive plasmid preps and the "stringy 
stuff" was fairly promenent in suspended cultures.

Hope this helps,
David
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