Do I have to pick signle colony in such a case? - (Jun/24/2008 )

Have plasmid from miniprep, and want to do a maxiprep.
I did a transformation and grew them on Amp+ LB plate. But there are too many colonies on the plate. Do I have to pick single colony from the plate? Someone suggest just scrape some. Someone even suggest directly transfer those transformants (in SOC media) directly to Amp+ LB media, and don't need to plate them.
Are these ways all right?

I would just dilute the DNA and retransform to get a single colony to save any pain. If the miniprep plasmid was prepared from a single colony then virtually all the colonies will be fine. So sure, it will work and probably be fine by those methods but in reality who knows what you're growing - some deleted vectors, some mutated vectors, some correct vectors, some something else vectors. And if your experiments don't work you'll think, "Hmmm, was it because i didn't pick a single colony?". Single colonies gives you one thing. And if it's correct then you can be completely confident in your preparation.

Hallo, the best way is to pick up just one colony and transfer it to the antibiotic-liquid LB. So you can by sure there is uniform population of cells harboring the same plasmid since they have rised from single cell.
I strongly recomend you to do this way. If you use smadge from plate there can by several geneticali different types. You never know what happens with billions of cells when growing
good luck

I would get a sterile loop and take a smear of bacteria from your plate, streak this out onto a fresh plate and then the following day pick a single colony to continue on with