In Vitro Fecal Fermentation Patterns of Arabinoxylan from Rice Bran on Fecal Microbiota from Normal-Weight and Overweight/Obese Subjects

Abstract

Arabinoxylan (AX) is a structural polysaccharide found in wheat, rice and other cereal grains. Diets high in AX-containing fiber may promote gut health in obesity through prebiotic function. Thus, the impact of soluble AX isolated from rice bran fiber on human gut microbiota phylogenetic composition and short-chain fatty acid (SCFA) production patterns from normal-weight and overweight/obese subjects was investigated through in vitro fecal fermentation. Results showed that rice bran arabinoxylan modified the microbiota in fecal samples from both weight classes compared to control, significantly increasing Collinsella, Blautia and Bifidobacterium, and decreasing Sutterella, Bilophila and Parabacteroides. Rice bran AX also significantly increased total and individual SCFA contents (p < 0.05). This study suggests that rice bran AX may beneficially impact gut health in obesity through prebiotic activities.

Keywords: arabinoxylan; gut microbiome; rice bran fiber; short-chain fatty acids.

Figure 1

Total and individual short-chain fatty acids (SCFAs) during in vitro fecal fermentation (n = 13; NW = 6, OO = 7). Treatments with different letters indicate significant differences at p < 0.05 based on the Friedman test and the corresponding multiple testing procedure. The medians are marked with red triangles. The weight classes are labeled by green circles (NW) and blue squares (OO). FOS: fructooligosaccharides, AX: arabinoxylan.

Figure 2

Microbial composition at phylum level during in vitro fecal fermentation. (a) The composition of microbiota at phylum level; (b) effect of time and weight on composition of Bacteroidetes. The Wilcoxon signed test was used for the effect of time (0 and 24 h), and the Mann–Whitney test was used for the effect of weight (NW and OO) at each time point (0 and 24 h).

Figure 3

Relative abundance of microbiota at the 24 h time point at phylum level (n = 12; NW = 6, OO = 6). (a) Bacteroidetes; (b) Firmicutes; (c) Proteobacteria; (d) Actinobacteria; (e) Fusobacteria; (f) Verrucomicrobia. Treatments with different letters indicate significant differences at p < 0.05 based on the Friedman test and the corresponding multiple testing procedure. The medians are marked with red triangles. The weight classes are labeled by green circles (NW) and blue squares (OO). AX: arabinoxylan.

Figure 4

Microbial composition at genus level during in vitro fecal fermentation (n = 12; NW = 6, OO = 6). (a) The composition of microbiota at genus level; (b) effect of time and weight on composition of Prevotella. The Wilcoxon signed test was used for the effect of time (0 and 24 h), and the Mann–Whitney test was used for the effect of weight (NW and OO) at each time point (0 and 24 h).

Figure 5

Relative abundance of microbiota at the 24 h time point at genus level (n = 12). (a) Prevotella; (b) Bacteroides; (c) Faecalibacterium; (d) Escherichia/Shigella; (e) Collinsella; (f) Blautia; (g) Sutterella; (h) Bifidobacterium; (i) Bilophia; (j) Alistipes; (k) Clostridium XIVb; (l) Clostridium XIVa; (m) Coprococcus; (n) Dorea; (o) Parabacteroides. Treatments with different letters indicate significant differences at p < 0.05 based on the Friedman test and the corresponding multiple testing procedure. The medians are marked with red triangles. The weight classes are labeled by green circles (NW) and blue squares (OO). AX: arabinoxylan.

Figure 5

Relative abundance of microbiota at the 24 h time point at genus level (n = 12). (a) Prevotella; (b) Bacteroides; (c) Faecalibacterium; (d) Escherichia/Shigella; (e) Collinsella; (f) Blautia; (g) Sutterella; (h) Bifidobacterium; (i) Bilophia; (j) Alistipes; (k) Clostridium XIVb; (l) Clostridium XIVa; (m) Coprococcus; (n) Dorea; (o) Parabacteroides. Treatments with different letters indicate significant differences at p < 0.05 based on the Friedman test and the corresponding multiple testing procedure. The medians are marked with red triangles. The weight classes are labeled by green circles (NW) and blue squares (OO). AX: arabinoxylan.