Amp stock survival?

[Chris Boyd]

Trevor Fenning (trevor.fenning at hri.ac.uk) wrote:
:      Hi There,
:      
:      Not long is the answer  - ampicillin goes off very fast indeed (half 
:      life at 37oC = 18 hours) even without resistant bacteria degrading it, 
:      so don't kep stocks at room temp, or even in the fridge.  
:      
:      I keep 1000x stocks made up in 1 ml aliquots at -20 which seem to 
:      last, although they will deterioate eventually.  If you are using it 
:      to select for transformants, always include controls of 
:      non-resistant/non transformed cells on the amp media.  That way you 
:      will notice any loss of effectiveness early.

I second all that, and also recommend dissolving Ap in 70% EtOH.  This
has the dual benefits of staying liquid at -20 and being less prone to
lose sterility.

Best wishes,
--
Chris Boyd                       | from, | MRC Human Genetics Unit
chrisb at hgu.mrc.ac.uk             |  not  |  Western General Hospital
http://www.hgu.mrc.ac.uk/~chrisb |   for |   Edinburgh EH4 2XU, SCOTLAND