Xylanase modulates the microbiota of ileal mucosa and digesta of pigs fed corn-based arabinoxylans likely through both a stimbiotic and prebiotic mechanism

Abstract

The experimental objective was to characterize the impact of insoluble corn-based fiber, xylanase, and an arabinoxylan-oligosaccharide on ileal digesta and mucosa microbiome of pigs. Three replicates of 20 gilts were blocked by initial body weight, individually-housed, and assigned to 1 of 4 dietary treatments: a low-fiber control (LF), a 30% corn bran high-fiber control (HF), HF+100 mg/kg xylanase (HF+XY), and HF+50 mg/kg arabinoxylan oligosaccharide (HF+AX). Gilts were fed their respective treatments for 46 days. On day 46, pigs were euthanized and ileal digesta and mucosa were collected. The V4 region of the 16S rRNA was amplified and sequenced, generating a total of 2,413,572 and 1,739,013 high-quality sequences from the digesta and mucosa, respectively. Sequences were classified into 1,538 mucosa and 2,495 digesta operational taxonomic units (OTU). Hidden-state predictions of 25 enzymes were made using Phylogenetic Investigation of Communities by Reconstruction of Unobserved States 2 (PICRUST2). Compared to LF, HF increased Erysipelotrichaceae_UCG-002, and Turicibacter in the digesta, Lachnospiraceae_unclassified in the mucosa, and decreased Actinobacillus in both (Q<0.05). Relative to HF, HF+XY increased 19 and 14 of the 100 most abundant OTUs characterized from digesta and mucosa, respectively (Q<0.05). Notably, HF+XY increased the OTU_23_Faecalibacterium by nearly 6 log2-fold change, compared to HF. Relative to HF, HF+XY increased genera Bifidobacterium, and Lactobacillus, and decreased Streptococcus and Turicibacter in digesta (Q<0.05), and increased Bifidobacterium and decreased Escherichia-Shigella in the mucosa (Q<0.05). Compared to HF, HF+AX increased 5 and 6 of the 100 most abundant OTUs characterized from digesta and mucosa, respectively, (Q<0.05), but HF+AX did not modulate similar taxa as HF+XY. The PICRUST2 predictions revealed HF+XY increased gene-predictions for enzymes associated with arabinoxylan degradation and xylose metabolism in the digesta, and increased enzymes related to short-chain fatty acid production in the mucosa. Collectively, these data suggest xylanase elicits a stimbiotic and prebiotic mechanism.

Fig 1

Summary of phylum, family, and genus-level microbial composition (>1% relative abundance) in the ileal digesta and mucosa among pigs (N = 60): A) Relative abundance of phyla present in the ileal digesta; B) Relative abundance of phyla present in the ileal mucosa; C) Relative abundance of families present in the ileal digesta; D) Relative abundance of families present in the ileal mucosa; E) Relative abundance of genera present in the ileal digesta; F) Relative abundance of genera present in the ileal mucosa.

Fig 2. Impact of treatment on measures of α–diversity within the ileal digesta and mucosa.

Fig 3. The relative abundance of the 15 most abundant genera among treatments present in the ileal digesta and mucosa.

Fig 4. The log₂-fold change difference between LF vs. HF, HF vs. HF+XY, HF vs. HF+AX for the 15 most abundant microbial genera present in the ileal digesta and mucosa with a Q-value < 0.05.

Fig 5

The log₂-fold change difference between LF vs. HF for the significant OTUs from the 100 most abundant OTUs among treatments present in the ileal digesta (A) and mucosa (B).

Fig 6

The log₂-fold change differences between HF vs. HF+XY for the significant OTUs from the 100 most abundant OTUs among treatments present in the ileal digesta (A) and mucosa (B).

Fig 7

The log₂-fold change differences between HF vs. HF+AX for the significant OTUs from the 100 most abundant OTUs among treatments present in the ileal digesta (A) and mucosa (B).

Fig 8. The log₂-fold change between HF vs. HF+XY or HF vs. HF+AX for the PICRUST2 predicted gene counts for enzymes associated with bacterial arabinoxylan degradation, xylose metabolism, or short chain fatty acid metabolism in the ileal digesta that tended or significantly differed.

Fig 9. The log₂-fold change between HF vs. HF+XY for the PICRUST2 predicted gene counts for enzymes associated with bacterial arabinoxylan degradation, xylose metabolism, or short chain fatty acid metabolism in the ileal mucosa that tended or significantly differed.