Can it be used for e. coli transformation if JM109 stock is expired? Is there any chance of even one single colony growing on lb plate treated with 100 mg/ml ampicillin by using expired JM109 stock?
What do you mean by expired? How has your stock been stored? A glycerol stock stored at -80C should be viable for years if not decades.
Sorry, I wasn't really thinking when I replied. If you are using chemically competent cells they should be OK for a few years if properly stored. How old are they?
The brand of JM109 is promega. The tubes stored at -80c all the time. But, I noticed that there's an expired date on the tube itself. So, I guess that it can be no longer to use anymore for preparing competent cells by plating on the lb plate and then, getting single colony of E. coli competent cell.
*The expired date is in may of 2012.,it's nearly one year from the date.
Budak- these cells will work fine. Companies won't guarantee the performance of competent cells past their use-by date, but they don't expire in the sense of suddenly failing to work altogether. Even if you lose some cloning efficiency (5-10x fewer colonies, and I doubt you'd see this steep a decline), you can probably compensate by plating a large fraction of the transformation reaction. Try to run a positive control using pUC19 so you can unambiguously measure transformation efficiency. Good luck!
E. coli JM109 competent cells can be used after several years. Incase you doubt their competency, there are simple methods by which you can grow them and prepare highly efficient cells. See this link
http://openwetware.org/wiki/Preparing_chemically_competent_cells_%28Inoue%29
I have two questions , the first one is how can I increase growth of competent cells DB3.1 in LB btoth media containing amp / kanamycin
The second , I use vector BACMAM pCMV dest which contains lethal gene CCdb and needs LR mix reaction , in the protocol it's mentioned that LR mix reaction transformed in DH10BAc , so can I use DH5alpha or DH10 B instead of DH10Bac .. ?
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