An improved method for detecting foreign DNA in plasmids of Escherichia coli.

A new procedure has been developed for lysing bacterial colonies on nitrocellulose filters and immobilizing the released DNA on the filters. The procedure involves the use of lysozyme and Triton X-100. When used in conjunction with in situ hybridization, this method has proven effective in detecting DNA recombinants, while eliminating the problems of false positives and variation between duplicate filters that are seen with other methods.