Effect of sturgeon protein in promoting the adhesion of Lactobacillus plantarum and Lactobacillus rhamnosus

Abstract

Dietary protein could serve as primary nitrogen source for intestinal flora to enhance the intestinal environment by influencing probiotic adhesion. Our work aims to demonstrate a framework for probiotic activity guided isolation of potential effective fractions from the sturgeon protein. We confirmed the isolated fractions of sturgeon protein as having probiotic adhesion activity against Lactobacillus plantarum 45 (LP45) and Lactobacillus rhamnosus GG (LGG). Three protein fractions (0%, 40%, and 60% NaCl elution fractions) were obtained through anion exchange resin column. The molecular weights of the three fractions were identified by polyacrylamide gel electrophoresis in the ranges of 20.1–66.4 kDa (Fr1), 14.3–44.3 kDa (Fr2) and 14.3–97.2 kDa (Fr3), respectively. A detailed study was performed using an in vitro adhesion model to obtain the bioactive protein. In this model, probiotics were incubated on isolated intestinal segments of mice, and the adhesion effect of probiotics was evaluated through polysaccharide analysis, biofilm quantification, viable count measurement and electron microscopy. Notably, Fr2 was identified as the most effective fractions, significantly increasing the intestinal adhesion rates of LP45 and LGG by 144.8% and 53.7%, respectively. Ultimately, the primary structure of the protein 14.3 kDa in Fr2 was identified by mass spectrometry. Partial peptide amino acid sequences of the protein were confirmed to be W-W-Y-C-F (m/z = 804), K-N-H-D-I/L-Q-A-D-D-I/L-T-C (m/z = 1510) and Q-M-V-H-K-I/L-E-D-E-E-I/L-C-T-S-A-D-K-D (m/z = 2300). In conclusion, we found evidence that purified fractions of sturgeon protein facilitates the adhesion of intestinal probiotics and can be used as an active protein beneficial for intestinal health.