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E.coli culture and miniprep help - (Mar/23/2007 )

Recently I have been having major difficulty getting plasmid out of my e.coli. I made new plates and media with a fresh stock of amp. The transformation (into Stbl2) cells works well and I get clear colonies on the plates after 24 hours. The problem is with the media cultures. After an overnight incubation, the cultures are completely overgrown and smell bad. I pelleted the bacteria, and i had two layers (the bottom layer appeared to be the e.coli cells, the top layer seemed to be a spongy, milky film). This has never happened before, and I have no idea what caused it. Does anyone else? Any ideas how I can get my DNA out? The plasmid has a lentiviral genome. Any help is much appreciated.


-Tara T-

It could be that your plasmid is toxic to the bacteria or your culture maybe infected with a phage. Try growing you plasmid for a shorter period of time and see if it helps.