You can detect the presence of bacteriocins by well diffusion method. In this method, after bacterium growth in the selective medium, make centrifugation to get supernatant. inoculate the sensitive bacteria in suitable medium, make holes with a diameter of 6 to 8 mm with a sterile cork borer and introduce about 50 -200 µL/well. incubate the plates under suitable conditions depending upon the sensitive microorganism. No growth occurs in the presence of bacteriocins and the inhibition zone depends on bacteriocin concentration.