Moderate dietary protein restriction alters the composition of gut microbiota and improves ileal barrier function in adult pig model

Peixin Fan,Ping Liu,Xi Ma,Peixia Song,Xiyue Chen

doi:10.1038/srep43412

Abstract

This study was conducted to investigate impacts of dietary protein levels on gut bacterial community and gut barrier. The intestinal microbiota of finishing pigs, fed with 16%, 13% and 10% crude protein (CP) in diets, respectively, were investigated using Illumina MiSeq sequencing. The ileal bacterial richness tended to decrease when the dietary protein concentration reduced from 16% to 10%. The proportion of Clostridium_sensu_stricto_1 in ileum significantly decreased, whereas Escherichia-Shigella increased with reduction of protein concentration. In colon, the proportion of Clostridium_sensu_stricto_1 and Turicibacter increased, while the proportion of RC9_gut_group significantly decreased with the dietary protein reduction. Notably, the proportion of Peptostreptococcaceae was higher in both ileum and colon of 13% CP group. As for metabolites, the intestinal concentrations of SCFAs and biogenic amines decreased with the dietary protein reduction. The 10% CP dietary treatment damaged ileal mucosal morphology, and decreased the expression of biomarks of intestinal cells (Lgr5 and Bmi1), whereas the expression of tight junction proteins (occludin and claudin) in 13% CP group were higher than the other two groups. In conclusion, moderate dietary protein restriction (13% CP) could alter the bacterial community and metabolites, promote colonization of beneficial bacteria in both ileum and colon, and improve gut barrier function.

Highlights

The balance of climax bacterial community has established in gut of finishing pigs, with the structure of bacterial composition remaining relatively stable
The finishing pigs were selected as the experimental model, and the effects of reducing dietary protein level by different percentage on the gut health from perspective of gut microbiota, intestinal barrier function and proliferation of intestinal stem cells were investigated
The overall Operational taxonomic units (OTUs) numbers classified at the distance level of 0.03 (97% similarity) were 1,015, with 398 detected in ileal samples, 920 in colonic samples, and 303 were shared by both

Summary

Introduction

The balance of climax bacterial community has established in gut of finishing pigs, with the structure of bacterial composition remaining relatively stable. The influence of different dietary CP levels on the intestinal bacterial communities have been widely studied in weaned piglets, the balance of intestinal microbiota has not been well established yet[13,14]. These studies were performed by using the traditional culture-dependent methods or low throughput culture-independent methods, and only bacteria that could be cultured in vitro or abundant in vivo were well detected. The finishing pigs were selected as the experimental model, and the effects of reducing dietary protein level by different percentage on the gut health from perspective of gut microbiota, intestinal barrier function and proliferation of intestinal stem cells were investigated. The result of our study might be a reference that suggests proper dietary protein intake for adults

Methods

Results

Discussion

Conclusion