Making frozen cell pellets competent - (Aug/31/2006 )
i was wondering if anyone knew if making competent cells out of E. coli bacterial cell pellets that have been frozen down at -20 degrees overnight is a no-no. the cells were harvested at an OD600 of ~0.5. i am using the Qiagen competent cell protocol for M15[pRep4] cells.
you can always try it ("have you done the experiment?" as my old mentor always said), but I bet your efficiency will be less. freezing is hard on cells, and you need to baby and nurture your e coli to get good efficient comp cells
re culture the coli is relative fast, and frozen coli cells are not suitable for good efficiency of transformation.
I agree with fred. Re culture your cells. It's very quick.