Purification, Structural Characterization, and Immunomodulatory Activity of an Exopolysaccharide from BJ01 in Fermentation Grains.

This study aims to identify the chemical structure and immunomodulatory activity of exopolysaccharides (EPSs) from BJ01 and suggest its potential applications in the pharmaceutical field and as functional food additives. The EPS-1 produced by . BJ01 was purified using column chromatography. The lyophilized powder obtained by vacuum freeze-drying was used for structural characterization and immunomodulatory activity analysis. Gel permeation chromatography (GPC) determined its molecular weight as 156.58 kDa. High-performance anion-exchange chromatography (HPAEC) identified that the EPS-1 is composed of mannose, xylose, and glucose. The structural characterization of EPS-1 by gas chromatography-mass spectrometry (GC-MS) and 1D/2D nuclear magnetic resonance (NMR) spectroscopy demonstrated that EPS-1 is primarily composed of α-D-Man-(1→, →2,6)-α-D-Man-(1→, →2)-α-D-Man-(1→, and →3)-α-D-Man-(1→. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) illustrated that EPS-1 exhibited a round, flake-like morphology. In vitro experiments with RAW264.7 macrophages demonstrated the high immunomodulatory activity of EPS-1. Significant upregulation of iNOS, IL-6, and TNF-α mRNA levels was confirmed by qRT-PCR ( < 0.05). Western blotting revealed that EPS-1 (6.25 μg/mL) induced phosphorylation of NF-κB (p65, IκBα) and MAPK (ERK) signaling proteins. This study provides the first structural and immunomodulatory characterization of an exopolysaccharide from BJ01, highlighting its potential as a novel immune adjuvant.