Identification and purification of a novel adhesion-associated protein in a new strain of Lactobacillus, L15, from flounder (Paralichthys olivaceus)

Adhesion is a crucial and prerequisite step for Lactobacillus colonization in the digestive tract which subsequently confers its probiotic effects on the host. The aim of this report was to identify and purify a novel adhesion-associated protein which mediates the adherence of a new strain of Lactobacillus, L15, to intestinal mucus from flounder. It was shown that surface proteins were involved in the adhesion of L15 to flounder mucus. The adhesion efficiencies of this strain were significantly decreased from 16.0% to 5.8% after extraction of L15 with 5 M LiCl and were further inhibited to 3.6% by blocking with an L15 cell extract containing surface proteins. The adhesion-associated protein in the cell extract was visualized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and was identified by Western blotting with sulfo-N-hydroxysuccinimide-biotin (B-NHS)-labeled crude mucus as a 61.8 kDa protein. The identical protein could be purified from L15 whole cell proteins by affinity chromatography using Sepharose, covalently coupled with crude mucus. It was demonstrated that the adhesion-associated protein was a new adhesive protein. Its characteristics and similarities with other known adhesive proteins need further investigation.