Competent cell storage for long term use - (Nov/10/2010 )

Hi,

As a part of my research, I do transformation of E.Coli DH5 alpha cells very often. And everytime I need to do transformation, I am advised to prepare fresh competent cells(chemical, CaCl2 mediated competent cell preparation). However, when I check the web, I see most of the people are using stored competent cells that were kept in -80 Celcius. However, when we do 15% glycerol stocks of the cells, they can keep their competency for only up to a month. What may be the possible problems in our approach? And what are your suggestions?

Thanks for your attention

personally I've kept competent cells for up to 6 months in -80 and they still work fine. It's troublesome to prepare fresh every time. don't do that.

If you follow the protocols supplied on the web for frozen competent cells (e.g. this one) they should last several months in the freezer. The preparation for immediate use competent cells is different and should not be frozen.