growing competent cells - (Jun/22/2011 )
I was given a small vial of top 10 invitrogen competent cells and wanted to grow more. If I plated them and grow them in LB media without antibiotics. Will they still be competent or do you have to make them competent again? If i grow a liter and spin it down what is the best way to transfer the cells from the flask to vials to store in -80 and do i add glycerol. thanks
You have to make them competent again.
There is little point in growing a litre and then freezing aliquots- as they will not be competent. Two frozen glycerol stocks should be sufficient (one working stock, and the other back up in case of contamination, accidentally left out etc).
But yes if you are wanting to freeze down bacterial cells (competent or otherwise) you must add glycerol as a cryoprotectant.
Hope that helps.