DataSheet1_Enzymatic Preparation of Low-Molecular-Weight Laminaria japonica Polysaccharides and Evaluation of Its Effect on Modulating Intestinal Microbiota in High-Fat-Diet-Fed Mice.DOC

Recent studies have shown that seaweed polysaccharides can ameliorate high-fat-diet (HFD)-induced metabolic syndromes associated with the regulatory function of gut microbiota. However, kelp, a natural source of seaweed polysaccharides, is highly viscous, making it difficult to prepare dietary fiber by simple degradation. Therefore, we developed a novel method of preparing low-molecular-weight polysaccharides from Laminaria japonica by combining high-pressure pretreatment and composite enzymatic degradation and evaluated the obesity prevention activity of these polysaccharides. Seaweed L. japonica polysaccharides (SJP) were rapidly utilized by the human fecal microbiota in vitro, resulting in the generation of short-chain fatty acids (SCFAs), specifically acetate and propionate. The in vivo effects of SJP on the intestinal microbiota were also investigated using HFD-fed C57BL/6J mice. SJP reduced weight gain and fat deposition in HFD-fed mice and increased the concentration of total SCFAs, including acetate, propionate, and butyrate in the feces. SJP ameliorated HFD-induced gut microbiota dysbiosis, resulting in increased abundance of Faecalibaculum, Romboutsia, and Clostridium sensu stricto 1 and decreased abundance of Blautia and Lactobacillus. Further, SJP enhanced the abundance of Akkermansia muciniphila in mice provided with HFD and normal chow. Single-strain culture experiments also revealed that SJP promoted the growth of A. muciniphila. This study highlights the potential use of SJP, prepared using composite enzymatic degradation (cellulase and recombinant alginate lyase), in preventing obesity and restoring intestinal homeostasis in obese individuals.

已有研究表明，海藻多糖（seaweed polysaccharides）可改善高脂饮食（high-fat-diet, HFD）诱导的代谢综合征，其作用与肠道菌群（gut microbiota）的调控功能相关。然而，作为海藻多糖的天然来源，海带（kelp）黏度极高，难以通过简单降解法制备膳食纤维。为此，本研究开发了一种结合高压预处理与复合酶解（composite enzymatic degradation）的新方法，从海带（Laminaria japonica）中制备低分子量多糖（low-molecular-weight polysaccharides），并评估了此类多糖的抗肥胖活性。体外实验显示，人类粪便菌群（fecal microbiota）可快速利用海带多糖（Seaweed L. japonica polysaccharides, SJP），并产生短链脂肪酸（short-chain fatty acids, SCFAs），具体为乙酸与丙酸。本研究还通过高脂饮食喂养的C57BL/6J小鼠，探究了SJP对肠道菌群的体内效应。SJP可降低高脂饮食喂养小鼠的体重增长与脂肪沉积，并提升粪便中总短链脂肪酸（SCFAs，含乙酸、丙酸与丁酸）的浓度。SJP可改善高脂饮食诱导的肠道菌群失调（gut microbiota dysbiosis），使粪杆菌属（Faecalibaculum）、朗伯根菌属（Romboutsia）与梭菌属狭义群1（Clostridium sensu stricto 1）的丰度升高，同时降低布劳特氏菌属（Blautia）与乳杆菌属（Lactobacillus）的丰度。此外，无论小鼠饲喂高脂饲料还是正常饲料，SJP均可提升嗜黏蛋白阿克曼氏菌（Akkermansia muciniphila）的丰度。单菌株培养实验同样证实，SJP可促进嗜黏蛋白阿克曼氏菌（A. muciniphila）的生长。本研究证实，通过复合酶解（纤维素酶（cellulase）与重组褐藻酸裂解酶（recombinant alginate lyase））制备的SJP，在预防肥胖及恢复肥胖人群肠道稳态（intestinal homeostasis）方面具有应用潜力。