BACTERIOCINS - NATURE, FUNCTION AND STRUCTURE

Bacteriocins are extracellular substances produced by different types of bacteria, including both Gram positive and Gram negative species. T hey can be produced spontaneously or induced by certain chemicals such as mitomycin C. They are biologically one of the important substances , and have been found to be useful in membrane studies and also in typ ing pathogenic microorganisms causing serious nosocomial infections. B acteriocins are a heterogeneous group of particles with different morp hological and biochemical entities. They range from a simple protein t o a high molecular weight complex; the active moiety of each molecule in all cases seems to be protein in nature. The genetic determinants o f most of the bacteriocins are located on the plasmids, apart from few which are chromosomally encoded. These bactericidal particles are spe cies specific. They exert their lethal activity through adsorbtion to specific receptors located on the external surface of sensitive bacter ia, followed by metabolic, biological and morphological changes result ing in the killing of such bacteria. This review summarises the classi fication, biochemical nature, morphology and mode of action of bacteri ocins as well as their genetic determinants and the microbiological re levance of these bactericidal agents. (C) 1997 Published by Elsevier S cience Ltd.