**1. Introduction**

Most of the commercially available food preservatives are synthesized chemically, causing a lot of toxic effect on human health. The increase in the consumption of packed food which require preservatives for long-term storage has created a need for the production of minimally processed food free of any chemical additives. The present-day food industry is therefore looking for natural substitutes that have no adverse effect on consumers and on the surroundings to replace the existing chemical preservatives. Lactic acid bacteria (LAB) have been known since ages for their use in traditional fermented foodstuff owing to their capability to bring enviable changes in flavor, taste and for inhibiting food spoiling pathogenic microorganisms, thus making them an attractive natural biopreservative [1]. LAB are in general considered to be food grade microorganisms and assumed to be secure for human consumption as they get degraded when they come in contact with human gut by the action of proteases; hence, also contemplated as generally regarded as safe (GRAS)

organisms. These are known to show preservative effect owing to their capability to produce hydrogen peroxide, organic acids, diacyls, and bacteriocins. Among all these, the antimicrobial compounds, bacteriocins, have received a greater attention as natural preservatives because nearly all of them are heat tolerant up to a particular temperature range and are amenable to proteolytic inactivation [1].

The bacteriocins are known to be produced by both positively and negatively Gram stained bacteria, however, the highest number of bacteriocins studied and identified are reported to be the antimicrobial peptides of Gram positive bacteria. A freely available database, BACTIBASE, which is totally dedicated to bacteriocins, consists of almost 177 sequences of bacteriocins out of which 156 belong to Gram positive bacterial strains, and the remaining 18 belong to Gram negative [2]. Production of bacteriocin depends on their genetic determinants; genes for bacteriocin production are reported to be localized either on plasmid or chromosomes [3]. These antibacterial peptides are synthesized on ribosomes and are known to show a bactericidal activity against identical or approximately related species [1]. Bacteriocins confer their bactericidal mode of action by creating a pore in the target cell, thus helping in combating the food pathogens.
