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

Abstract 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.