[Mechanisms of the antibiotic activity of bacteriocins]

Some bacteria possesses the genetic capacity to synthesize compounds referred to as bacteriocins; such compounds are antagonic for other closely related bacteria by inhibiting bacterial growth. These toxic substances are either simple polypeptides or very complex macromolecules. However the feature of being a "killer" strain is coded by chromosomal or plasmid genes. The mechanism of lethal action is carried out either directly or indirectly against certain functions of the target cell; death of the sensitive strain is produced as a consequence of transport collapse at membrane level resulting in a drastic drop of indispensable metabolites or ions; in other cases the antibacterial effect produces blocking of macromolecule synthesis; or loss of metabolite stabilization within the cell altering the basic metabolism. Repercussions of bacteriocinogeny may be: use as epidemiological tool through bacteriocin-typing techniques; biological control by means of specific bacteriocins; regulation of bacterial growth rate in a population as a competence mechanism for a given ecological habitat; genetic transfer between competent cells; study of superficial receptor sites and its role in natural immunity; use as therapeutic agents through a number of problems like cross-toxicity and specificity of action still remain unsolved.