Optimization Preparation and Property Analysis of Sulfate Polysaccharide from Eucheuma spinosum by Probiotic Fermentation

To prepare Eucheuma spinosum sulfated polysaccharides with low viscosity, high solubility and high bioavailability, fermented Eucheuma spinosum sulfate polysaccharides (F-ESP) was prepared by fermenting Lactobacillus rhamnoides, a common probiotic bacteria in fermented food, response surface methodology was used to optimize the preparation process with the yield of crude polysaccharide as the index. Low temperature freeze-thaw Eucheuma spinosum sulfate polysaccharide (L-ESP) was used as control. After purification by DEAE-52 column chromatography, the contents of total sugar, reducing sugar, sulfate and other substances and monosaccharide composition were determined, and the chemical composition of F-ESP was analyzed. The physical properties of F-ESP were characterized by viscosity, solubility, molecular weight and microstructure. The functional group structure of F-ESP was analyzed by infrared spectroscopy. The antiallergic activity of F-ESP was evaluated by Rat Basophilic Leukemia-2H3 (RBL-2H3) degranulation assay. When the ratio of material to liquid was 1:70, the inoculation amount was 5%, and the fermentation time was 24 h, the yield of crude polysaccharide was the highest (41.70%±2.00%). The purified F-ESP-3 monosaccharide structure was mainly composed of galactose, and the total sugar content was 97.77%±1.10%. The sulfate content was 28.40%±1.40%. Compared with L-ESP-3, the reducing sugar content of F-ESP-3 (7.87%±0.09%) was significantly higher, the molecular weight (33.58 kD) was significantly decreased (P<0.01), the specific viscosity (0.01±0.002 dL/g) was significantly lower (P<0.01), and the solubility (89.33%±3.10%) was significantly higher (P<0.0l). Under scanning electron microscope, L-ESP-3 was smooth and dense flake, and F-ESP-3 was rough and irregular granule. The sugar chain structure of F-ESP-3 prepared by fermentation did not change. It was a kind of α-pyranose sulfate containing 3-methylether-galactose residue, and inhibit the activation of basophils by inhibit the release of β-hexosaminidase. To sum up, probiotic fermentation could be used as a way to prepare Eucheuma spinosum sulfated polysaccharides, and its anti-allergic activity could be significantly improved by changing its physical properties. This result provides data support and theoretical basis for the industrial production, development and utilization of Eucheuma spinosum polysaccharides.