a protein substance released by certain bacteria that kills but does not lyse closely related strains of bacteria

A small, naturally occurring protein produced by one species of bacterium that effectively protects it from competing organisms. Different bacteria produce different bacteriocins.

A protein produced by bacteria of one strain and active against those of a closely related strain.

A protein antibiotic, one or more types of which can be produced and "exported" (excreted) by certain strains of bacteria. ( 16)

Bacteriocins are proteinaceous toxins produced by bacteria to inhibit the growth of similar or closely related bacterial strain(s). They are phenomenologically analogous to yeast and paramecium killing factors, and are structurally, functionally, and ecologically diverse.