Objective: To investigate the effects of fermentation by Lactobacillus plantarum (ATCC 14917), Saccharomyces cerevisiae (ATCC 9763), and Bacillus subtilis (ATCC 9327) on the structural characteristics and bioactivities of mulberry polysaccharides (MPs). Methods: Three fermented MPs (MFP-Z, MFP-N, MFP-K) and an unfermented control (MFP) were prepared using ultrasound-assisted extraction. Their structural features were characterized by high-performance liquid chromatography (HPLC) and high-performance gel permeation chromatography (HPGPC). The antioxidant, hypoglycemic and immunomodulatory activities were systematically evaluated in vitro. Results: Fermentation significantly increased the yield and total sugar content of MPs, while altering their molecular weights and monosaccharide compositions. MFP, MFP-N and MFP-Z consisted of nine monosaccharides (mannose, glucosamine hydrochloride, rhamnose, glucuronic acid, galacturonic acid, glucose, galactose, xylose, and arabinose) with distinct molar ratios. MFP-K additionally contained galactosamine hydrochloride. Fermentation with L. plantarum increased the molecular weight of MPs, whereas B. subtilis and S. cerevisiae fermentation reduced it. FT-IR spectroscopy confirmed that the major functional groups of MPs were retained after fermentation. For bioactivities, the overall antioxidant capacity followed the order MFP-N>MFP-K>MFP-Z>MFP, and the hypoglycemic activity ranked MFP-N>MFP-Z>MFP-K>MFP. Moreover, MFP-K and MFP-N markedly enhanced macrophage phagocytosis and stimulated the secretion of NO, TNF-α, and IL-6. Conclusion: Microbial fermentation can modulate the structure and enhance the bioactivities of mulberry polysaccharides in a strain-dependent manner without damaging the main functional groups. This study provides an effective strategy for the high-value utilization of mulberry polysaccharides in functional foods and pharmaceuticals.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |