Alkaline lysis

Alkaline lysis is a method used in molecular biology to break cells open to isolate plasmid DNA or other cell components such as proteins. Bacteria containing the plasmid of interest is first grown, then lysed with a strong alkaline buffer consisting of a detergent sodium dodecyl sulfate (SDS) and a strong base sodium hydroxide. The detergent breaks the membrane's phospholipid bilayer and the alkali denatures proteins involved in maintaining the structure of the cell membrane. Through a series of steps involving agitation, precipitation, centrifugation, and the removal of supernatant, cellular debris is removed and the plasmid is isolated and purified. The protocol may vary slightly from lab to lab.

Also, alkaline lysis is sometimes used to extract plant genetic material. The plant cells are subjected to a strongly alkaline solution containing a detergent (usually a zwitterionic or nonionic detergent such as Tween 20), and the mixture is incubated at high temperature. This method is not used as often due to the sodium hydroxide's tendency to damage genetic material, reducing DNA fragment size.