Curing plasmids from a strain

j.r.stephen mbi071 at sysc.abdn.ac.uk
Thu Jun 5 07:26:42 EST 1997


Hi Martin,

In the past, when I've wanted to get rid of pBR322 derivatives from E. coli
strains, I've found that simply growing them in LB 2x overnight cultures without
antibiotic selection has done the trick without any nasties. I just plated out,
picked 100 colonies and replica plated them on LB and LB Amp, about 20% had lost
the plasmid.

No promises, but might be worth a try?

All the best,

John Stephen

Donald Lueking (dlueking at up.net) wrote:
: Dr Martin Goldberg wrote:

: > I have a strain with a pBR322-based plasmid and I want to cure the
: > strain of this plasmid. Is there any way of achieving this without
: > using agents such as ethidium bromide? I am considering
: > competing-out
: > the plasmid by transforming the strain with pBR322 or one of its
: > other derivatives and selecting for this latter plasmid. Has anybody
: > got an
: > opinion on this approach or are there any more elegant methods?
: > *****************************************

: Martin,
:     Curing by plasmid incompatibility should work fine as long as you
: have a good, unique marker for the second plasmid.  Most, if not all, of
: the curing procedures I know of are purely empirical (SDS,EtBr, etc.).
: Incompatibility would probably be one of the mildest procedures you
: could use.

: Don




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