Lactic Acid Bacteria: A Potential Tool in Biological Preservation of Food

Lactic acid bacteria (LAB) have a major role in biopreservation of foods because they are considered safe and are designated as GRAS (Generally Recognized as Safe) organisms. The preservative property of LAB is attributed to the combined action of a range of antimicrobial substances viz. lactic acid, acetic acid, propionic acid, carbon dioxide, hydrogen peroxide, bacteriocins and antifungal peptides. Acids produced by these bacteria reduce the pH and inhibit the growth of a wide range of microbes such as Gram positive and Gram negative bacteria, yeast and moulds. The secondary metabolite reuterin, has been reported to have a broad spectrum of activity and inhibits fungi, protozoa and bacteria. Phenyllactic acid which is one of the major compounds produced by some strains of LAB possesses antifungal activity. These antimicrobial metabolites represent a promising natural device for controlling fungal contaminants in different food systems including vegetables and fruits, dairy and bakery products. In this review the data available on various antimicrobial metabolites produced by different strains of LAB has been compiled. The potential application of antifungal LAB has also been discussed.