Characterization and comparison of the adherence and immune modulation of two gut Lactobacillus strains isolated from Paralichthys olivaceus

In order to identify highly-adhesive probiotic lactobacilli, the adherence and immune modulation of Lactobacillus sakei PO11 (LS-PO11) and L. plantarum PO23 (LP-PO23) which were isolated from the intestine of healthy wild olive flounder (Paralichthys olivaceus) were studied in this work. The significant differences in acid resistance, bile resistance, cell surface hydrophobicity and surface-layer proteins (SLPs) were confirmed between two lactobacilli. In comparison with LS-PO11, LP-PO23 exhibited higher adherence to the intestinal epithelial cell and colonization level in the intestine. When treated with LiCl, both LS-PO11 and LP-PO23 exhibited significant reduction in adherence to the intestinal epithelial cell. Finally, the expression of IL-1β, TNF-α, MHC-II, Ig M and TCR-β genes were significantly up-regulated in gill and head kidney treated with two lactobacilli respectively. The peak expression levels of these five genes were much higher in LP-PO23 treated gill and head kidney than that treated with LS-PO11, except for IL-1β in head kidney which was detected almost the same between two lactobacilli. These results indicated that LP-PO23 was more suitable to be a highly-adhesive and potential probiotics and would facilitate better understanding of strain specificity exhibited in lactobacilli adherence and immune modulation.