Bacteriocinogeny: Concept, nomenclature, prevalence and application

Microbes produce an extraordinary array of microbial defense systems. These include broad spectrum low molecular weight classical antibiotics; metabolic by-products such as ammonia, organic acids and hydrogen peroxide; lytic agents such as lysozymes; numerous types of protein exotoxins; defective bacteriophages and bacteriocins. Antibiotics are defined as natural, semisynthetic or wholly synthetic substances that kill or inhibit the growth of microorganisms at low concentrations. One abundant class of antibiotics of bacterial origin is the bacteriocins. These are produced by both Gram positive and Gram negative bacteria, and even Archaea most frequently during stationary phase of growth. Bacteriocins are loosely defined as biologically active protein moieties with a bactericidal mode of action. The proteinaceous compounds range from 1 to 100 kD, and are ribosomally synthesized. They can alter cell membrane integrity and interfere with transcription, translocation or DNA replication. They differ from traditional antibiotics in one critical way that they have a relatively narrow killing spectrum and are mostly toxic to bacteria which are closely related to the producing strain. The sensitive strain does not develop resistance similar to antibiotic resistance. Bacteriocins appear to mediate population dynamics within species. This intrinsic property of bacterial strains has led to studies for thir potential use as biopreservatives, therapeutic agents and biocontrol organisms in agriculture including competitive strains of Rhizobium for effective bioinoculants. In this review, some of the aspects of bacteriocinogeny particularly their prevalence in microbial world have been discussed.