low plasmid yields in dh5alpha

Ed Siefker via methods%40net.bio.net (by ebs15242 from creighton.edu)
Wed Feb 20 13:56:30 EST 2008

Hi.  We've been going through our old plasmids and making
fresh stocks.  We've found a few that we're not able to
miniprep and get reasonable concentrations (<50ng/ul).
We're using Qiagen miniprep kits and invitrogen dh5alpha
and have had much success purifying

One thought was that the plasmids might be producing a
product that is toxic to dh5alpha, and maybe they'd do
better in another strain. Has anyone had a similar problem
that was resolved by growing the plasmid in another strain?

I'm thinking XL1-blue might help because it retains the
lac repressor, and that might help stop any background
expression from the lac promoter.  Any other ideas would
be appreciated.  Thanks

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