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Ampicillin plates

Jon Nakamoto jnakamot at ucla.edu
Thu Dec 7 06:42:24 EST 1995

This has become a problem in our lab, too, and I suspect it has something
to do with the age of the ampicillin powder we keep in our refrigerator
(how old is yours?). If anyone knows the suggested effective lifespan of
ampicillin powder at +4 degrees C, please let me know. 


Jon Nakamoto, MD
UCLA Medical Center
jnakamot at ucla.edu

In article <4a582r$lcj at news1.ucsd.edu>, rcaspi at sdcc3.ucsd.edu (Ron Caspi) wrote:

> Hi everybody
> Lately we have been having hard time with ampicillin plates in our
> lab. I can't figure out what we're doing wrong: we prepare stock
> solution of 100 mg/ml ampicillin in water, and add them to LB medium
> just before we pour the plates (not too hot) to a concentration of 100
> or 150 ug/ml. Alas, there is a major problem of satelite colonies
> growing around the resistant colonies when we spread-plate
> transformation mixtures. Any idea?
> Thanks for any input
> PS It would be best if you could cc your reply to my email, so I won't
> miss a reply.
> ________________________________________________________________________
> Ron Caspi
> Scripps Institution of Oceanography               Phone   (619) 534-0638
> La Jolla  CA  92093-0202                          Fax     (619) 534-7313

Jon Nakamoto
jnakamot at ucla.edu

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