Bacteriocin antibiotic. Coloured transmission electron micrograph (TEM) of bacteriocins (orange), a type of antibiotic produced by bacteria. These proteins, seen surrounded by bacterial cell debris, resemble viruses as they have a tubular head and thin tail. They mainly attack other bacteria by disrupting essential cell functions or by breaking down their cell walls. Characteristically, the bacteria that releases the bacteriocins is also killed in the process. The first bacteriocins to be discovered were those of the E. coli bacterium in the 1920s. Negatively- stained. Magnification: x109,300 at 6x7cm size. Magnification: x375,000 at 7x9.5 size."