A method for detecting restriction endonucleases in bacterial colonies

A simple technique is proposed for detection of bacterial restriction endonucleases. Analysis is performed directly in the cells from colonies cultivated on Petri dishes. The cells collected with an inoculation loop are treated with lysozyme and Triton X-100. After centrifugation the supernatant is tested for endonuclease activity. The technique enables up to 100 colonies to be tested for 3-4 h.