gayler at immunex.com wrote:
: Here is a puzzler. We have recently had a problem with
: satellite colonies on O/N growth of our Amp plates. This
: usually happens once a year or so. We have performed all
: manner of controls, such as increasing Amp concentration
: to 350ug/ml, making new Amp stocks, buying new Amp from
: other vendors. We have spread Amp on top of fresh LB
: plates (15cm) at varying concentrations (up to the
: equivalent of 1 mg/ml!) We still get some satellites,
: particularly with high copy number plasmids. We see
: satellites whether there are 200 colonies or if there are
: 10.The number of satellites decreases with increasing Amp
: but with certain plasmids, such a pGEX, they still remain.
: We don't believe the Amp is being heat-inactivated since
: we have taken special care, and the spreading experiments
: used fresh Amp. Different people have also been involved
: in making plates.We are using concentrations of Amp that
: It appears to me that something is inactivating the Amp but
: I don't know what.
: We are getting somewhat frustrated. The problem will
: probably go away soon, but I'm sure it will return again.
: Is there something that could be sequestering the Amp? Would
: carbenicillin be more effective? Any help would be appreciated.
: Richard Gayle
:gayler at immunex.com: --
: The opinions expressed are solely my own.
We use 80ug/ml methicillin and 20ug/ml amp with no satellites ever.
J_Petitte at NCSU.EDU