3.11 Purifying Plasmid DNA

Any of the commonly used techniques for purifying nucleic acids from bacterial cells may be used to isolate and purify plasmid DNA from E. coli..


Figure 23. Separation of DNA fragments by gel electrophoresis

If small amounts of DNA are enough for the experimental purpose, cells may be lysed directly using alkaline conditions. The host DNA will be denatured, but the supercoiled plasmid DNA will not. The two forms of DNA may be separated easily by gel electrophoresis or density-graadient centrifugation and recovered for use.