BACTERIOCINS PRODUCED BY LEUCONOSTOC SPECIES

Leuconostoc spp. are lactic acid bacteria that are commonly associated with foods and that are used as starter bacteria in some dairy fermen tations. Lactic acid bacteria are inhibitory to other bacteria because of pH, organic acids, hydrogen peroxide, and other chemicals produced during their growth, including bacteriocins. Bacteriocin production b y Leuconostoc spp. was first observed in the 1950s, but only since 198 4, when antagonistic activity of Leuconostoc spp. was reported, have m ore extensive studies of bacteriocins produced by Leuconostoc spp. bee n conducted, including mesentericin Y105, produced by Leuconostoc mese nteroides ssp. mesenteroides; leucocin A-UAL 187, produced by Leuconos toc gelidum; carnosin 44A, produced by Leuconostoc carnosum; and leuco nocin S, produced by Leuconostoc paramesenteroides. Bacteriocins produ ced by leuconostocs may or may not be active against other lactic acid bacteria, but all include Listeria in their activity spectra. Mesente ricin Y105 is reported to be exclusively active against Listeria spp. The amino acid sequences for leucocin A and mesentericin Y105 have bee n determined. Despite considerable differences in antibacterial spectr a, only two amino acids differ between these bacteriocins. The prevale nce of leuconostocs in many adventitious fermentations of food and the use of leuconostocs as starter bacteria in controlled fermentations m ake the bacteriocins produced by these bacteria of interest as possibl e food preservatives by addition of the bacteriocin or its producer or ganism to foods.