Exopolysaccharide production in lactic acid bacteria and their antagonistic effects on pathogenic bacteria

Abstract: Background and Objectives: Exopolysaccharides (EPS) are the natural polymers mainly produced by plants and some bacteria, including lactic acid bacteria. This study was designed to investigate the amount of EPS produced by L.casei, L.reuteri, L.bulgaricus and L.plantarum from the Species Lactobacillus and the antagonistic effects of these bacteria on some pathogenic bacteria. Materials and methods: The four mentioned Lactobacilli were inoculated to MRS-Broth medium and incubated for 24 hours anaerobically at 37° C. From the previous culture medium the bacteria were transferred to the MRS-Broth containing cysteine to be incubated for 24 h at 37° C. subcultures were made in MRS broth containing cystein and tube were incubated at 37° C anaerobically for120 hours to provide mucoid and soft colonies. The Lactobacilli colonies were left at room temperature for 24 hours before measuring exopolysaccharide production rate using phenol-sulfuric acid method. The EPS production levels were determined through comparison with the glucose standard curve. The antagonistic effects of the Lactobacilli culture suspension on Escherichia coli, Staphylococcus aureus, Acintobacter and Pseudomonas aeruginosa were investigated. Results: Lactobacillus casei as compared to with the other species had significantly (p<0.05) more potential to produce EPS. The culture of all Lactobacilli indicated significant (p<0.05) antagonistic effects on the pathogenic bacteria. The results of this study indicated that lactic acid bacteria have the potential to produce EPS and their broth culture can suspension express the antagonistic effects on some pathogenic bacteria. Discussion: Given the prevalence of antibiotic resistance in pathogenic bacteria, the use of alternative therapies using probiotic bacteria more seriously proposed. Keywords: Exopolysaccharides, Lactic acid bacteria, antagonists, pathogenic bacteria

Exopolysaccharide; antagonistic;pathogenic bacteria