Bacteriocin

Bacteriocins are proteinaceous toxins given off by bacteria to inhibit the growth of similar bacterial strain(s). E. coli bacteriocins are called colicins.

To demonstrate their production, technicians stab inoculate multiple strains on separate multiple nutrient agar Petri dishes, incubate at 30°C for 24 hrs., overlay each plate with one of the strains (in soft agar), incubate again at 30°C for 24 hrs. After this process, the presence of bacteriocins can be inferred if there are zones of growth inhibition around stabs.