A new method for purifying lambda DNA from phage lysates.

A new method for preparing small quantities of lambda DNA from phage lysates has been developed. The protocol is based on the concentration and purification of bacteriophage particles from crude lysates using small DEAE-cellulose columns. This chromatographic step gives an absolute separation of the lambda DNA from the cellular nucleic acids and a 20-fold enrichment relative to the major soluble proteins in crude lysates, while effecting a 10-fold concentration of the phage. Final deproteinization and concentration of the lambda DNA is achieved by conventional precipitation steps. The lambda DNA produced by this method is shown to be nondegraded, biologically active, and an excellent substrate for restriction enzymes. A detailed protocol is provided for starting with individual plaques and using the method to obtain purified DNA from large numbers of lambda clones.