Characterization of probiotic properties of lactic acid bacteria isolated from intestinal microbiota of fish

The aim of this study was to evaluate the ability of three lactic acid bacteria (LAB) isolated from fish, Lactococcus lactis CLFP 101, Lactobacillus plantarum CLFP 238, and Lactobacillus fermentum CLFP 242 to inhibit adhesion of several fish pathogens (Aeromonas hydrophila, Aeromonas salmonicida, Yersinia ruckeri and Vibrio anguillarum) to host intestinal mucus under in vitro conditions. The results showed that only Lc. lactis CLFP 101 reduced the adhesion of all fish pathogens, whereas L. plantarum CLFP 238 reduced the adhesion of A. hydrophila and A. salmonicida. With the exception of V. anguillarum, the adhesion of all fish pathogens to intestinal mucus was reduced by L. fermentum CLFP 242 and by mixture of the three LAB strains. In addition, only Lc. lactis CLFP 101 showed antibacterial activities against all fish pathogens as measured in spent culture liquid. All LAB strains were able to survive relatively low pH and high fish bile concentrations. Based on the positive results of this study, Lc. lactis CLFP 101, L. plantarum CLFP 238 and L. fermentum CLFP 242 should be further studied in challenge experiments in fish to explore their probiotic effects.