Structure of β-glucan from Tibetan hull-less barley and its in vitro fermentation by human gut microbiota

• Main Authors: Chenxi Nie, Xin Yan, Xiaoqing Xie, Ziqi Zhang, Jiang Zhu, Yangfan Wang, Xinlei Wang, Nan Xu, Yiwen Luo, Zhen Sa, Xinyang Li, Huicui Liu, Baoming Tian, Qingyu Ma, Min Zhang, Zhifei Chen, Juxiu Li
• Format: Article
• Language: English
• Published: SpringerOpen 2021-02-01
• Series: Chemical and Biological Technologies in Agriculture
• Subjects: Tibetan hull-less barley 25; Neutral polysaccharide; Structural characterization; Gut microbiota
• Online Access: https://doi.org/10.1186/s40538-021-00212-z

Abstract Background The influence of β-glucan on the human gut microbiota is closely related to the physicochemical structure of β-glucan. We purified a homogeneous water-soluble polysaccharide from Tibetan hull-less barley 25 and studied its structure and the in vitro fermentation profile. Results Analysis by gas chromatography (GC), Fourier-transformed infrared (FT-IR), nuclear magnetic resonance (NMR), scanning electron microscopy (SEM), and atomic force micrograph (AFM) helped determine the hull-less barley polysaccharide to be a β-glucan (molecular weight: 3.45 × 104 Da), which was further characterized as mixed-linkage (1 → 3)(1 → 4)-linked β-d-glucans. SEM images demonstrated an intricate web structure of the hull-less barley polysaccharide, while the AFM images revealed the presence of small spherical particles in its structure. In addition, the microbiota composition of the hull-less barley polysaccharide group was found to be altered, wherein the abundance of Pantoea, Megamonas, Bifidobacterium, and Prevotella-9 were increased. On the other hand, in vitro fermentation revealed that hull-less barley polysaccharide significantly decreased the pH value and increased the production of acetate, propionate, and butyrate. Conclusions Hull-less barley polysaccharide is a type of dietary fiber, and its analysis suggested that it may serve as a prebiotic food supplement for the regulation of the gut microbiota.