The Effect of Xylooligosaccharide, Xylan, and Whole Wheat Bran on the Human Gut Bacteria

Abstract

Wheat bran is a cereal rich in dietary fibers that have high levels of ferulic acid, which has prebiotic effects on the intestinal microbiota and the host. Herein we explored the effect of xylooligosaccharide, xylan, and whole wheat bran on the human gut bacteria and screened for potential ferulic acid esterase genes. Using in vitro fermentation, we analyzed the air pressure, pH-value, and short-chain fatty acid levels. We also performed 16S rRNA gene and metagenomic sequencing. A Venn diagram analysis revealed that 80% of the core operational taxonomic units (OTUs) were shared among the samples, and most of the xylooligosaccharide treatment core OTUs (319/333 OTUs) were shared with the other two treatments’ core OTUs. A significant difference analysis revealed that the relative abundance of Dorea, Bilophila, and Sulfurovum in wheat bran treatment was higher than that in xylan and xylooligosaccharide treatments. The clusters of orthologous groups of proteins functional composition of all samples was similar to the microbiota composition of the control. Using metagenomic sequencing, we revealed seven genes containing the conserved residues, Gly-X-Ser-X-Gly, and the catalytic triad, Ser-His-Asp, which are thus potential ferulic acid esterase genes. All the results indicate that xylan and/or xylooligosaccharide, the main dietary fibers in wheat bran, plays a major role in in vitro fermentation by the human gut microbiota.

Supplementation of xylo-oligosaccharides to suckling piglets promotes the growth of fiber-degrading gut bacterial populations during the lactation and nursery periods

“…Bacteroides are major primary degraders of oligo- and polysaccharides with a close relationship with XOS, containing the most expanded glycolytic gene repertoires that target xylan degradation 49 . In fact, different in vitro tests have demonstrated that XOS stimulates Bacteroides growth in the microbial ecosystem 16 , 50 . The abundance of Lachnospiraceae in mice fed a high-fat diet was increased by XOS, increasing the formation of butyric acid in the cecum 17 .…”

“…Among dietary fiber compounds, xylo-oligosaccharides (XOS) are oligomers composed of 2–6 xylose units linked through β-(1 → 4)-linkages 15 . Their selective fermentation has been shown to induce changes in both composition and activity of the gastrointestinal microbiota, stimulating the growth of butyrate-producing bacteria 16 , 17 . Butyrate has been associated with benefits in intestinal health, such as the modulation of the mucosal inflammatory response and barrier function 18 , 19 .…”

Engineering the Active Site Pocket to Enhance the Catalytic Efficiency of a Novel Feruloyl Esterase Derived From Human Intestinal Bacteria Dorea formicigenerans

“…In our previous work, seven potential FAE genes were identified from in vitro fermentation of human fecal slurry using metagenomic sequencing ( Chen et al, 2020 ) in which one FAE from Alistipes shahii ( As FAE) was characterized ( Wei et al, 2021 ). Here, a novel FAE from Dorea formicigenerans ( Df FAE) of Firmicutes was bacterially expressed and purified to assess its enzymatical properties.…”

The α-Helical Cap Domain of a Novel Esterase from Gut Alistipes shahii Shaping the Substrate-Binding Pocket

“…12 Several other reports further proved the existence of FAEs in human intestines. 13,14 In our previous study, an upregulation of seven FAE genes was observed during the in vitro fermentation of fecal slurry using cereal-rich wheat bran, suggesting that FAEs from the intestinal flora play an important role in releasing free FA in foodstuff. 14 In 2004, for the first time, Wang et al isolated, purified, and characterized an FAE from the gut bacterium Lactobacillus acidophilus exhibiting maximum activity at 37 °C and pH 5.6.…”

“…13,14 In our previous study, an upregulation of seven FAE genes was observed during the in vitro fermentation of fecal slurry using cereal-rich wheat bran, suggesting that FAEs from the intestinal flora play an important role in releasing free FA in foodstuff. 14 In 2004, for the first time, Wang et al isolated, purified, and characterized an FAE from the gut bacterium Lactobacillus acidophilus exhibiting maximum activity at 37 °C and pH 5.6. 15 Different FAEs from the intestinal flora exhibited distinct activities.…”