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Freeze transformation mixture? - (Jan/28/2013 )

Hello,

I had a microcent tube of chemically competent DH5a that I used for a transformation procedure to insert a plasmid. I had about 100ul of transformation "broth" leftover and I want to store it to possibly use again in the future, so I put it in the freezer. I thought since the DH5a has undergone transformation and presumably took up the plasmid that it is now just another E. coli, so I thought it would be okay to freeze it (but now that I think about it I normally don't freeze other cells in broth...). Anyway the DH5a was in SOC medium and the last time I check the tube the medium was still liquid (although quite viscous). Can these cells still be thought of as similar to newly transformed cells or no? Next time if I want to save the remaining mixture where do I put it? In the refrigerator?

Thanks

-tihong10-

Many of the cells will be dead due to freeze/thaw damage. However, some will survive but they should not be treated as OK - the general rule is "If in doubt, throw it out".

You can store transformed cells in the fridge for a few days, but the viability drops quite quickly.

-bob1-

I see, thanks for the tip.

I tried plating the frozen transformation mixture and nothing grew : /

-tihong10-