Site-Specific Gut Microbiome Changes After Roux-en-Y Gastric Bypass in Rats: Effects of a Multicomponent Bovine Colostrum-Based Complex

Abstract

Roux-en-Y gastric bypass (RYGB) surgery induces profound gut microbiota alterations that may impact metabolic outcomes. This study investigated site-specific effects of a multicomponent bovine colostrum-honey-serviceberry (CHJ) complex on post-RYGB microbiome changes in obese rats. Twenty-nine Wistar rats underwent RYGB surgery with CHJ supplementation, followed by mucosal-associated microbiota analysis from five gastrointestinal segments using 16S rRNA sequencing and serum metabolite profiling. RYGB caused regional-specific changes: decreased alpha diversity, systematic Proteobacteria increases (31.2 ± 5.1% in duodenum), and reductions in SCFA-producing bacteria (Romboutsia, Roseburia). CHJ supplementation exhibited dual effects on the microbiome: restoration of beneficial bacteria (Lactobacillus, Bifidobacterium) in distal segments while concurrently promoting Enterobacteriaceae growth in proximal regions. CHJ also maintained alpha diversity levels of the mucosa-associated microbiota comparable to those observed in the control group. Disconnects emerged between predicted microbial functions and systemic metabolites: thiamine pathway activation accompanied 78.5% serum vitamin B1 reduction, indicating severe absorption deficits. Three distinct patterns emerged: pro-inflammatory (proximal), decolonization (widespread Helicobacteraceae loss), and restorative (selective CHJ-mediated recovery). Results demonstrate that post-RYGB dysbiosis exhibits profound regional heterogeneity requiring segment-specific interventions and highlight complex interactions between nutritional supplementation and surgically altered gut ecology in determining metabolic outcomes.

Keywords: Enterobacteriaceae; Roux-en-Y gastric bypass; SCFA-producing bacteria; bariatric surgery; bovine colostrum; dysbiosis; gut microbiome; metabolic syndrome; site specificity.

Figure 1

Flowchart of the animal experiment.

Figure 2

Microbiome diversity and composition changes following RYGB surgery. (A) Alpha diversity indices (ACE, FaithPD, Pielou) showing significant reductions after RYGB, with CHJ supplementation restoring diversity levels. (B) Pairwise ANOSIM dissimilarity matrices showing intragroup dissimilarities by segment. (C) Principal Coordinates Analysis (PCoA) based on unweighted UniFrac distances demonstrating regional specificity of microbiome changes. (D) Firmicutes/Bacteroidetes ratio changes across gastrointestinal segments. Groups: CN/SD—lean control; CHJ-control—animals receiving CHJ; CHJ-RYGB—post-RYGB animals receiving CHJ; OB-RYGB—post-RYGB obese animals without supplementation. Statistical significance: * p < 0.05, ** p < 0.01, *** p < 0.001.

Figure 3

Taxonomic shifts in gut microbiome at phylum level following RYGB surgery. (A) Heatmap showing differential abundance patterns across comparisons between groups at phylum and class levels. (B) Relative abundance (%) of major bacterial phyla across gastrointestinal segments. RYGB surgery resulted in significant increases in Proteobacteria, Bacteroidetes, and Fusobacteria, while decreasing Campylobacterota and Patescibacteria in region-specific patterns. CHJ supplementation showed modulatory effects on these taxonomic shifts. Groups: CN/SD—lean control; CHJ-control—obese animals receiving CHJ; CHJ-RYGB—post-RYGB animals receiving CHJ; OB-RYGB—post-RYGB animals without supplementation. ↑: non-overlapping 95% CI.

Figure 4

Effects of CHJ supplementation on functionally important bacterial groups following RYGB surgery. Changes in classical probiotics (green), SCFA producers (blue), and metabolically beneficial bacteria (red) across five gastrointestinal segments. Data shown as relative abundance (%) with statistical significance indicators.

Figure 5

Site-specific changes in gut microbiome composition at the family level across different gastrointestinal segments following RYGB surgery and CHJ supplementation. (A) Relative abundance (%) of the most abundant bacterial families. (B) Heatmap showing differential abundance patterns across comparisons between groups at family level. (C) Relative abundance (%) of major bacterial families in duodenum (MAM-D), jejunum (MAM-J), ileum (MAM-I), large intestine (MAM-LI), and fecal samples. Groups: CN/SD—control without obesity (n = 7); CHJ-control—obese animals receiving CHJ (n = 7); CHJ-RYGB—post-RYGB animals receiving CHJ (n = 10); OB-RYGB—post-RYGB animals without supplementation (n = 5). Arrows indicate statistically significant differences with non-overlapping 95% CI, p < 0.05.

Figure 6

Predicted metabolic functions of gut microbiome and correlations with systemic metabolism. (A) Serum levels and metabolite concentrations in groups. (B) PICRUSt2 analysis of predicted metabolic pathways showing changes in vitamin B metabolism (ko00730—Thiamine metabolism), amino acid metabolism (ko00260, ko00360, ko00380), and folate biosynthesis (ko00790) across gastrointestinal segments.