Low concentration miniprep

Duncan Clark via methods%40net.bio.net (by blackhole from abuse.plus.com)
Mon Jan 19 04:45:32 EST 2009


Historians believe that in newspost 
<mailman.1461.1232227543.29717.methods from net.bio.net> on Sat, 17 Jan 2009, 
shifali  chatrath <shifalich from rediffmail.com> penned the following 
literary masterpiece:
>  Just a query! Are satellite colonies correctly defined as slow growing colonies or a daugther colony of nearby parent colony?


Neither.

Satellite colonies arise on electroporated/transformed E.coli ampicillin 
plates when the ampicillin resistant colony's beta lactamase destroys 
ampicillin in the vicinity of that colony. As there is now no ampicillin 
in the media around that colony, background non-plasmid plated E.coli 
cells start to grow, giving rise to so-called satellite colonies.

It doesn't happen with a kanamycin as the antibiotic is not destroyed.

The use of more beta lactamase resistant antibiotics such as 
carbenicillin will reduce satellite formation. I still use 80:20 
Methicillin:ampicillin, as I have a very old large bottle of methicillin 
from before Sigma stopped selling it.

Duncan
-- 
I love deadlines. I especially like the whooshing noise they make as
they go flying by.

Duncan Clark
GeneSys Ltd.


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