Effects of novel flavonoid-enriched yogurt on the diversity of intestinal microbiota in mice

Abstract

Soy isoflavone glycoside cannot be effectively absorbed by the human intestinal tract, but probiotics with related hydrolases can transform it into aglycone to promote its absorption. In this study, a novel flavonoid-enriched yogurt was developed using an isolated β-glucosidase-producing strain (Lactiplantibacillus plantarum GY). The flavonoid aglycone-enhanced yogurt was fed to ICR mice for 21 days, and its effects were observed. The yogurt can affect the gut microbial diversity of mice, especially increasing the abundance of Parasutterella, the Bacteroidales S24-7 group, and Phascolarctobacterium in the intestinal tract of mice. Meanwhile, the ratio of Bacteroidetes/Firmicutes in the intestinal tract of mice fed with the flavonoid aglycone-enriched yogurt increased. The difference in the content of butyric acid between the L-GY + IS and the control groups was significant (P < 0.05). Therefore, milk fermentation with β-glucosidase-producing strains is a promising approach for developing flavonoid glycoside-enriched yogurt products.

Keywords: Flavonoids; Gut microbiota; Lactiplantibacillus plantarum; Short-chain fatty acids; β-glucosidase.

Fig. 1

Identification of β-glucosidase-producing lactic acid bacteria. (A) Color development of isolated lactic acid bacteria on esculin tablets; (B) phylogenetic tree based on 16S rRNA gene sequences of strain GY, L11, and PC7. The evolutionary history was inferred using the Neighbor-Joining method, scale bar represents 0.01 nucleotide substitution per position

Fig. 2

Probiotic characteristics of isolated β-glucosidase-producing lactic acid bacteria. (A) Survival rate of isolated strains resist 1% bile salt; (B) colonies of isolated strains resist artificial gastric juice for 2 h and 4 h; (C) colonies of isolated strains resist artificial intestinal juice for 2 h, 4 h, and 6 h; (D) colonies of isolated strains resist different pH (4.0, 5.6, 7.0, 8.0). Data presented as means ± SD, n = 3. Data with the same letter in the top of column indicate that they are no statistically different (P > 0.05)

Fig. 3

Fermentation conditions of free-flavonoid aglycone-enriched yogurt. (A) The effect of fermentation temperature. (B) The effect of inoculum ratio. (C) The effect of pH. (D) Results of orthogonal experiment that for optimum fermentation conditions. (E) The flavonoid content of different yogurts produced by optimum fermentation conditions. Data presented as means ± SD, n = 3. Data with the same lowercase in the column indicate that they are no statistically different (P > 0.05) in the content of glycoside, and capital represent they are no statistically different (P > 0.05) in the content of aglycone

Fig. 4

Effects of the free-flavonoid aglycone-enriched on mice. (A) body weight index; (B) phagocytosis activity of peritoneal macrophages of the treated mice. Data presented as means ± SD from eight independent experiments. Data with the same letter in the column indicate that they are no statistically different (P > 0.05)

Fig. 5

Effects of the soy isoflavone yogurt on the gut microbiota change in feces. (A) The different of gut microbiota in 5 groups at phylum; (B) hierarchical tree of 5 groups on OTU level; (C) LEfSe analysis results of 5 groups

Fig. 6

Significant difference test between groups on genus level. Based on the community abundance data in the sample, the genus with different abundance in different groups of microbial communities were detected, and the significance of the observed differences was evaluated by Students’ t test. The boxes with different colors represent different groups, the y-axis represents the average relative abundance of a species in different groups, _* (P < 0.05), _** (P < 0.01). (A) The differences in group Con1 and L-GY + IS. (B) The differences in group Con2 and L-GY + IS. (C) The differences in group IS and L-GY + IS. (D) The differences in group L-GY and L-GY + IS. Different colors represent different genus, and the size of the circle indicates the number of species

Fig. 7

Effects of the soy isoflavone yogurt on SCFA concentrations in feces. Data presented as means ± SEM. n = 6 mice/group. The same letter indicates that there are no significant differences (P > 0.05) in the concentration of the SCFA in different groups