Antimicrobial activity of Lactobacillus plantarum strains against Salmonella pathogens.

Introduction. Lactic acid bacteria produce various compounds such as organic acids, diacetyl, hydrogen peroxide and bacteriocin during lactic fermentations. All of these can antagonize the growth of some spoilage and pathogenic bacteria in foods. Materials and methods. To determine the antimicrobial activity of Lactobacillus plantarum D1 and Lactobacillus plantarum D2 against Salmonella sp. and Salmonella abony ATCC 6017, the method of co-culturing was applied. The study was conducted under static conditions at 37±1 ºC for 72 hours, taking samples at 0, 12, 24, 36, 48, 60 and 72 h and monitoring the changes in the titratable acidity and the concentration of viable cells of both the pathogens and the Lactobacillus plantarum strains. Results and discussion. In the single-strain cultivation of each Lactobacillus plantarum strain and each Salmonella strain high concentration of viable cells were achieved by the 24th hour and it was maintained by the end of the culturing. In the co-culturing of each Lactobacillus plantarum strain and each Salmonella strain, the Lactobacillus strain was not significantly influenced by the presence of any of the Salmonella strains. But the number of viable cells of the pathogens was greatly reduced, the reduction being strainspecific. In the co-culturing of each Lactobacillus plantarum strain and Salmonella abony ATCC 6017, the concentration of viable cells of the pathogen strain was reduced by the 60th h. In the co-culturing of each Lactobacillus plantarum strain and Salmonella sp., the concentration of viable cells of the pathogen strain was reduced by the 72th h. The observed antimicrobial activity was due to a great extent to the acidification of the medium because of the production and accumulation of lactic and other oraganic acids. Conclusions. The demonstrated antimicrobial activity is a prerequisite for further research on the probiotic potential of the two Lactobacillus plantarum strains for their inclusion in the composition of probiotic preparations and starters for probiotic functional foods. [ABSTRACT FROM AUTHOR]