Abstract: Low molecular weight (LMW) levan was prepared from high molecular weight (HMW) levan produced by Paenibacillus bovis sp. nov BD3526 by the trichloroacetic acid (TCA) method with simultaneous removal of protein in HMW levan. The LMW levan was purified by anion-exchange chromatography. The molecular weight of the purified sample was determined by gel permeation chromatography (GPC). Its chemical structure was confirmed by nuclear magnetic resonance (NMR) and fourier transform infrared spectrometry (FT-IR). An atomic force microscope (AFM) was used to characterize its conformation in aqueous solution. To determine its potential impact on gut microbiota composition, in vitro fermentations using adult faecal inoculum treated with purified LMW levan and FOS were performed in a fermentation screening platform established by TNO (the Netherland). The results demonstrated the purified LMW levan could improve the growth of Bifidobacterium, especially B. infantis and B. longum. Furthermore, the levan was better than FOS in promoting the proliferation of B. infantis and B. longum.

Key words: levan; prebiotics; gut flora; bifidobacterium

摘要： 采用三氯乙酸(trichloroacetic acid,TCA)法除去Paenibacillus bovis sp.nov BD3526来源的高分子质量左聚糖中蛋白质的同时制备得到低分子质量左聚糖,并用离子交换层析法对低分子质量左聚糖进行分离纯化,用凝胶渗透色谱(gel permeation chromatography,GPC)法测定纯化后样品的分子质量及其分布,用核磁共振(nuclear magnetic resonance,NMR)仪和傅里叶变换红外光谱(fourier transform infrared spectrometer,FT-IR)表征其化学结构,用原子力显微镜(atomic force microscope,AFM)表征其在水溶液中的构象,最后采用荷兰应用科学研究(The Netherlands Organization For Applied Scientific Research,TNO)组织建立的体外筛选平台评价其对人体肠道菌群的调节作用.体外实验结果表明,此低分子质量左聚糖能促进双歧杆菌特别是婴儿双歧杆菌和长双歧杆菌的增殖,其促进作用优于低聚果糖(fructooligosaccharide,FOS).

关键词: 左聚糖；益生元；肠道菌群；双歧杆菌