Impact of an oligosaccharide-based polymer on the metabolic profiles and microbial ecology of weanling pigs experimentally infected with a pathogenic E. coli

Abstract

Background: Our previous study has reported that supplementation of oligosaccharide-based polymer enhances gut health and disease resistance of pigs infected with enterotoxigenic E. coli (ETEC) F18 in a manner similar to carbadox. The objective of this study was to investigate the impacts of oligosaccharide-based polymer or antibiotic on the host metabolic profiles and colon microbiota of weaned pigs experimentally infected with ETEC F18.

Results: Multivariate analysis highlighted the differences in the metabolic profiles of serum and colon digesta which were predominantly found between pigs supplemented with oligosaccharide-based polymer and antibiotic. The relative abundance of metabolic markers of immune responses and nutrient metabolisms, such as amino acids and carbohydrates, were significantly differentiated between the oligosaccharide-based polymer and antibiotic groups (q < 0.2 and fold change > 2.0). In addition, pigs in antibiotic had a reduced (P < 0.05) relative abundance of Lachnospiraceae and Lactobacillaceae, whereas had greater (P < 0.05) Clostridiaceae and Streptococcaceae in the colon digesta on d 11 post-inoculation (PI) compared with d 5 PI.

Conclusions: The impact of oligosaccharide-based polymer on the metabolic and microbial profiles of pigs is not fully understood, and further exploration is needed. However, current research suggest that various mechanisms are involved in the enhanced disease resistance and performance in ETEC-challenged pigs by supplementing this polymer.

Keywords: Carbadox; Colon microbiota; Enterotoxigenic E. coli F18; Metabolomics; Oligosaccharide-based polymer; Weaned pigs.

Fig. 1

Partial least squares discriminant analysis (PLS-DA) 2D score plot of the metabolites in serum (A and B) or distal colon digesta (C and D) showed separated clusters between the 10 or 20 mg/kg oligosaccharide-based polymer active substance and CAR groups on d 5 (A and C) or d 11 (B and D) post-inoculation, respectively. LOW = Control diet supplemented with 10 mg/kg of oligosaccharide-based polymer. HIGH = Control diet supplemented with 20 mg/kg of oligosaccharide-based polymer. CAR = Control diet supplemented with 50 mg/kg carbadox. Shaded areas in different colors represent in 95% confidence interval

Fig. 2

Significantly changed pathways (−log₁₀(P) value > 1.5) in serum between oligosaccharide-based polymer groups and 50 mg/kg of carbadox on d 5 (A) or d 11 (C) post-inoculation. The x-axis represents the pathway impact values and the y-axis represents the −log₁₀(P) values from the pathway enrichment analysis. Metabolite set enrichment analysis (B and D) shows the metabolic pathways were altered in 10 or 20 mg/kg of oligosaccharide-based polymer active substance groups compared to carbadox on d 5 or d 11 post-inoculation, respectively. Both pathway analysis and metabolite set enrichment analysis were performed using identified metabolites with VIP > 1

Fig. 3

Significantly changed pathways (−log₁₀(P) value > 1.5) in distal colon digesta oligosaccharide-based polymer groups and 50 mg/kg of carbadox on d 5 (A) or d 11 (C) post-inoculation. The x-axis represents the pathway impact values and the y-axis represents the −log₁₀(P) values from the pathway enrichment analysis. Metabolite set enrichment analysis (B and D) shows the metabolic pathways were altered in 10 or 20 mg/kg oligosaccharide-based polymer active substance groups compared to carbadox on d 5 or d 11 post-inoculation, respectively. Both pathway analysis and metabolite set enrichment analysis were performed using identified metabolites with VIP > 1

Fig. 4

Beta diversity of the microbiota in the distal colon digesta of enterotoxigenic E. coli F18 challenged pigs fed diets supplemented with different dose of oligosaccharide-based polymer active substance or carbadox on d 5 and 11 post-inoculation. Data were analyzed by principal coordinate analysis (PCoA) based on the Bray–Curtis dissimilarity. Symbols indicate dietary treatments and colors indicate different sampling dates. CON = Basal nursery diet (control); LOW = Control diet supplemented with 10 mg/kg of oligosaccharide-based polymer; HIGH = Control diet supplemented with 20 mg/kg of oligosaccharide-based polymer; CAR = Control diet supplemented with 50 mg/kg of carbadox

Fig. 5

Stacked bar plot showing the relative abundance of Firmicutes family in colon digesta of enterotoxigenic E. coli F18 challenged pigs fed diets supplemented with different dose of oligosaccharide-based polymer active substance or carbadox on d 5 and 11 post-inoculation (A). Violin plot showing the relative abundance of individual bacterial phylum (B). ^a−cMeans without a common superscript are different (P < 0.05). Each least squares mean represents 6 observations. CON = Basal nursery diet (control); LOW = Control diet supplemented with 10 mg/kg of oligosaccharide-based polymer; HIGH = Control diet supplemented with 20 mg/kg of oligosaccharide-based polymer; CAR = Control diet supplemented with 50 mg/kg of carbadox

Fig. 6

Stacked bar plot showing the relative abundance of Bacteroidetes family in colon digesta of enterotoxigenic E. coli F18 challenged pigs fed diets supplemented with different dose of oligosaccharide-based polymer active substance or carbadox on d 5 and 11 post-inoculation (A). Violin plot showing the relative abundance of individual bacterial phylum (B). ^a,bMeans without a common superscript are different (P < 0.05). Each least squares mean represents 6 observations. CON = Basal nursery diet (control); LOW = Control diet supplemented with 10 mg/kg of oligosaccharide-based polymer; HIGH = Control diet supplemented with 20 mg/kg of oligosaccharide-based polymer; CAR = Control diet supplemented with 50 mg/kg of carbadox