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Cutting DNA from non-E.coli

Michael Benedik benedik at uh.edu
Tue Feb 25 10:57:33 EST 1997

In article <hickey.44.3312145A at cmb.UNR.EDU>
hickey at cmb.UNR.EDU (Eileen Hickey) writes:

> We're trying to do Southern blots to test a probe for cloning genes from 
> several bacteria: Legionella, Neisseria meningitidis, S. pneumoniae, and S. 
> pyogenes. The DNAs we have are not cutting well, and it occurs to us that they 
> may be modified? Has anyone cloned any genes from these bacteria? and what did 
> you cut with?

I think modification is unlikely. If you had one strain that didn't cut
with a particular enzyme, perhaps. But with multiple strains it is
highly unlikely they all have the same modficiation system. If you are
trying different enzymes then this would get around it.

I think it much more likely that your genomic DNA is just dirty. Lots
of bacterial produce copious amounts of polysaccharide or other nasties
that inhibit digestion (which E.coli doesn't make much of). 

Try purifying your DNA better, such as with multiple CTAB

Michael Benedik
Department of Biochemical Sciences
University of Houston
benedik at uh.edu

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