Combined effects of BARLEYmax and cocoa polyphenols on colonic microbiota and bacterial metabolites in vitro

Abstract

BARLEYmax, a barley variety, and cocoa polyphenols (CPPs) have been reported to affect bacterial metabolites in the colon. This study aimed to evaluate the combined effects of BARLEYmax and CPPs supplementation on fecal microbiota in vitro using pig feces for 48 h. The relative abundances of the family Clostridiaceae and the genus Clostridium and ammonia-nitrogen production were decreased by both BARLEYmax and CPP supplementation, and there was a positive correlation between their abundances and the ammonia-nitrogen concentration. Although acetate and n-butyrate production was decreased by CPP supplementation, their concentrations were maintained at a higher level in the BARLEYmax + CPP group than in the cellulose (control) and cellulose + CPP groups. Therefore, this study demonstrated that a combination of BARLEYmax and CPPs may be beneficial in maintaining higher short-chain fatty acid production and the elimination of potentially harmful factors.

Supplementary information: The online version contains supplementary material available at 10.1007/s10068-021-00959-z.

Keywords: BARLEYmax; Cocoa polyphenol; Colonic microbiota; Short-chain fatty acid; n-butyrate.

Fig. 1

Measurement of α-diversity using the Chao1 (A) and Shannon indices (B) and PCoA plot of β-diversity (C). Samples were obtained from the fermenters at 48 h during in vitro colonic fermentation. The data on α-diversity measured at the OTU level are expressed as mean ± SE (n = 5). Two-way ANOVA was performed to assess the effects of the carbohydrate source, CPP extract, and their interaction. Differences at p < 0.05 were considered as statistically significant. The weighted UniFrac distance metric in QIIME at the OTU level was used to determine the β-diversity. CEL, cellulose; BM, BARLEYmax; CPP, cocoa polyphenol; PCoA, principal coordinate analysis

Fig. 2

pH in fermenters during in vitro colonic fermentation at 0, 6, 12, 24, and 48 h of incubation. Data are expressed as the mean ± SE (n = 5). Two-way ANOVA was performed to assess the effects of carbohydrate source, CPP, and their interaction. Differences at p < 0.05 were considered as statistically significant. CEL, cellulose; BM, BARLEYmax; CPP, cocoa polyphenol

Fig. 3

Concentration of acetate (A), propionate (B), n-butyrate (C), and total-SCFAs (D) in fermenters during in vitro colonic fermentation at 0, 6, 12, 24, and 48 h of incubation. Data are expressed as the mean ± SE (n = 5). Two-way ANOVA was performed to assess the effects of carbohydrate source, CPP, and their interaction. If significant interactions were observed (p < 0.05), means among the groups were analyzed by ANOVA paired with Tukey’s test. ^a−cMean values at the same time point designated by different letters are significantly different (p < 0.05). CEL, cellulose; BM, BARLEYmax; CPP, cocoa polyphenol

Fig. 4

Ammonia–nitrogen concentration in fermenters during in vitro colonic fermentation at 0, 6, 12, 24, and 48 h of incubation. Data are expressed as the mean ± SE (n = 5). Two-way ANOVA was performed to assess the effects of the carbohydrate source, CPP extract, and their interaction. If significant interactions were observed (p < 0.05), means among the groups were analyzed by ANOVA paired with Tukey’s test. ^a−cMean values at the same time point designated by different letters are significantly different (p < 0.05). CEL, cellulose; BM, BARLEYmax; CPP, cocoa polyphenol