[P008] Poster

1:00 PM - 1:50 PM JST(4:00 AM - 4:50 AM UTC)

[P04-604] Effects of Digested Whole-Grain Bread on the Gut Microbiome and Metabolome in an In Vitro Fecal Fermentation Model

○Jun Hoi Kim¹, Hyunbin Seong¹, Nam Soo Han¹ (1. Brain Korea21 Center for Smart GreenBio Convergence and Sustainable Regional Development, Division of Animal, Horticultural, and Food Sciences, Chungbuk National University (Korea))

Keywords:

gut microbiome,gut metabolome,Whole-Grain Bread,in vitro fecal fermentation

Prebiotics are non-digestible food components that promote host health by selectively stimulating the growth and metabolic activity of beneficial gut microorganisms. Whole-grain bread is rich in dietary fiber and other fermentable substrates with potential prebiotic properties. However, its direct impact on gut microbial composition and metabolite production remains insufficiently characterized. In this study, we evaluated the intestinal effects of digested whole-grain bread samples using an in vitro fecal fermentation model designed to assess changes in the gut microbiome and metabolome. Whole-grain bread samples were subjected to in vitro digestion to simulate the upper gastrointestinal process, and the resulting digesta were subsequently applied to an in vitro fecal fermentation system. Fermentation was conducted for 16 h under anaerobic and pH-controlled conditions using FineGut medium inoculated with fecal microbiota obtained from 13 healthy adults. Microbial community changes were analyzed by 16S rRNA amplicon sequencing using the SILVA 132 database and the QIIME2 pipeline, while metabolite profiles in fermentation supernatants were assessed by ¹H-NMR spectroscopy. At the phylum level, Firmicutes and Bacteroidota were dominant across all treatment groups. Alpha diversity analysis showed that whole-grain bread-treated groups exhibited increased species richness compared with the white bread-treated group, indicating a potential stimulatory effect on gut microbial diversity. Beta diversity analysis further revealed distinct clustering patterns according to treatment, suggesting that digested whole-grain bread altered overall microbial community structure during fermentation. Taxonomic analysis demonstrated that whole-grain bread treatment increased the relative abundance of health-associated taxa, including Prevotella copri, Bifidobacterium catenulatum, Coprococcus comes, and Megamonas funiformis, while potentially harmful taxa such as Bacteroides vulgatus, B. plebeius, and B. coprocola tended to decrease. To assess metabolic alterations associated with microbial fermentation, gut microbial metabolites were analyzed after fermentation. Total short-chain fatty acid concentrations increased in all treatment groups, and the production of propionate and butyrate was significantly enhanced in the whole-grain bread-treated groups relative to the white bread-treated group. In contrast, TMA levels tended to decrease in several whole-grain bread-treated groups, indicating a potentially favorable shift in microbial metabolic output. Collectively, these findings suggest that digested whole-grain bread beneficially modulates gut microbial diversity, composition, and metabolic activity and may serve as a promising dietary substrate for promoting intestinal health.