Comparison of colicine production and diffusion on different solid media.

Using a freezing-thawing method for extracting colicine from solid media it has been shown that the choice of media for production and diffusion is important. Digest nutrient agar yielded the most colicine and peptone water agar the least. A factor in bacteriological peptone, but absent in a proteose peptone (Difco) and Neopeptone, was responsible for inhibiting production on peptone water agar. Dextrose reduced the diffusion of colicine. A minimum of six hours' incubation of the colicinogenic organism was required for satisfactory production of colicine.