Formula Probiotic Fermentation After Enzymatic Pretreatment Enhances Immunomodulatory Effects of Edible Seaweed <i>Sargassum fusiforme</i> via Gut Microbial Regulation

This study evaluated the efficacy of enzymatic pretreatment combined with formula probiotic fermentation in enhancing the structural and immunomodulatory properties of Sargassum fusiforme polysaccharides. Enzymatically pretreated and fermented polysaccharides (EFS) were obtained through enzymatic hydrolysis followed by fermentation with a multi-strain probiotic consortium (Lactobacillus plantarum, Lactobacillus acidophilus, and Bifidobacterium brevis). Structural analysis demonstrated that EFS exhibited a higher proportion of low-molecular-weight components (<10 kDa accounting for 18.3%), elevated total sugar (49.04%) and sulfate contents (14.40%), and a distinct monosaccharide profile compared to untreated or enzymatically pretreated samples. Functionally, EFS significantly promoted splenic lymphocyte proliferation in vitro (p < 0.05) and enhanced macrophage phagocytosis in a carbon clearance mouse model (p < 0.05). Mechanistically, the immunomodulatory effects were associated with a significant increase in the abundance of Lactobacillus in the gut, leading to the elevated production of immunomodulatory short-chain fatty acids, particularly propionic acid and butyric acid. These findings confirm that enzymatic pretreatment coupled with probiotic fermentation effectively optimizes the structural integrity and bioactivity of Sargassum fusiforme polysaccharides, positioning EFS as a promising functional food ingredient for gut-immune axis regulation. PRACTICAL APPLICATIONS: This research could lead to the development of novel functional food ingredients or dietary supplements derived from seaweed. These products would be designed to support human health by positively influencing the gut environment. The fermentation process aims to enhance the natural bioactive properties of the seaweed polysaccharides for such applications.