"Orange" pellet in plasmid mini-prep

Wolfgang Schechinger wgschech at med.uni-tuebingen.de
Wed Jun 10 18:32:52 EST 1998


It seems that your XL1-blue is no longer XL-1 blue. 
I recently had a similar observation; we decided that the culture 
was Staphylococcus aureus (the orange colour increased on standing),
autoclaved it and discarded it. Looking at the broth, it 
neither did look like E. coli nor it did smell.

The most important thing would be locating the source of 
contamination. If you know a microbiologist, you might let him 
have a look the bug, maybe he can tell you more. Then obtain some 
new bacteria to start with. 

Good luck!


> Hello!
> We are having an interesting problem with a very simple and standard
> technique.  At the moment, when we do DNA plasmid minipreps
> (pCRScript in XL-1B) from LB broth cultures +AMP, we are getting no
> plasmid. The growth appears normal in the broth, and also on LB+AMP
> plates.   We have tried different miniprep methods, new reagents,
> etc. etc., but nothing seems to work.  One thing that appears
> slightly different is that when we pellet the bacteria from the
> broth culture, the pellet appears slightly orange compared to what
> we are used to.  This is the only noticeable change from our
> normally problem-free techniques.  Not only have we noticed this
> problem, but other labs not related to ours are also currently
> having this problem, and noticing slightly orange pellets. 
>  Has anybody else ever seen this before?
> What caused it?
> (Most important) Is there a solution to this problem?
> Thank-you for your time.
> Ray Boykiw
> University of Calgary
> Faculty of Medicine
usual disclaimers apply * This message is RNAse free - please don't touch!
Wolfgang Schechinger         
University of Tuebingen, Germany
email: wgschech at med.uni-tuebingen.de * wwWait: http://www.medizin.uni-tuebingen.de/~wgschech/start.htm

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