An analysis of bacteriocins produced by lactic acid bacteria isolated frommalted barley

Aims: The aim of this study was to perform a detailed characterization of b acteriocins produced by lactic acid bacteria (LAB) isolated from malted bar ley. Methods and Results: Bacteriocin activities produced by eight LAB, isolated from various types of malted barley, were purified to homogeneity by ammon ium sulphate precipitation, cation exchange, hydrophobic interaction and re verse-phase liquid chromatography. Molecular mass analysis and N-terminal a mino acid sequencing of the purified bacteriocins showed that four non-iden tical Lactobacillus sakei strains produced sakacin P, while four Leuconosto c mesenteroides strains were shown to produce bacteriocins highly similar o r identical to leucocin A, leucocin C or mesenterocin Y105. Two of these ba cteriocin-producing strains, Lb. sakei 5 and Leuc. mesenteroides 6, were sh own to produce more than one bacteriocin. Lactobacillus sakei 5 produced sa kacin P as well as two novel bacteriocins, which were termed sakacin 5X and sakacin 5T. The inhibitory spectrum of each purified bacteriocin was analy sed and demonstrated that sakacin 5X was capable of inhibiting the widest r ange of beer spoilage organisms. Conclusions: All bacteriocins purified in this study were class II bacterio cins. Two of the bacteriocins have not been described previously in the lit erature while the remaining purified bacteriocins have been isolated from e nvironments other than malted barley. Significance and Impact of the Study: This study represents a thorough anal ysis of bacteriocin-producing LAB from malt and demonstrates, for the first time, the variety of previously identified and novel inhibitory peptides p roduced by isolates from this environment. It also highlights the potential of these LAB cultures to be used as biological controlling agents in the b rewing industry.