Trouble with Glycerol stocks of DH5alpha

[Duncan Clark]

In article: <43q7gn$g3m at dingo.cc.uq.oz.au>  A.Cavallaro at botany.uq.oz.au 
(Tony Cavallaro) writes:
> 
> In out lab lately we have bben trouble growing up DH5alpha cell 
> after they have been glycerol solution frozen at -80 degrees. They grow
> fine in LB-amp (50), but fail to give any DNA after a miniprep procedure.
> THis is unusual since we usually have no trouble with this.
> 
> Also another problem with minipreps, we are also having trouble growing 
> up colonies from plates (both LB agar and Mcconkey). The colonies look 
> good on the plate but do not grow up in liquid culture. We are using 
> DH5alpha again for this.

Sounds like the problem is more a plasmid/strain combination than just the 
strain. Ampicillin is also not the best selection as it is destroyed 
v.quickly. Try an 80/20 mix of methicillin/ampicillin. Also try other 
E.coli's not derived from DH5 background (I think DH5 is an MM294 deriv.).

Duncan
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