Effects of Different Diets on Microbiota in The Small Intestine Mucus and Weight Regulation in Rats

Yu Meng,Fanggen Lu,Chunlian Wang,Xiaojun Li,Jie Zhang

doi:10.1038/s41598-019-44994-7

Abstract

While the microbial community of the small intestine mucus (SIM) may also play a role in human health maintenance and disease genesis, it has not been extensively profiled and whether it changes with diet is still unclear. To investigate the flora composition of SIM and the effects of diet on it, we fed SD rats for 12 weeks with standard diet (STD), high-fat diet (HFD), high-sugar diet (HSD) and high-protein diet (HPD), respectively. After 12 weeks, the rats were sacrificed, SIM and stool samples were collected, and high-throughput 16S rRNA gene sequencing was used to analyze the microbiota. We found that fecal microbiota (FM) was dominated by Firmicutes and Bacteroidetes, while in SIM, Firmicutes and Proteobacteria were the two most abundant phyla and the level of Bacteroidetes dramatically decreased. The microbiota diversity of SIM was less than that of feces. The community composition of SIM varied greatly with different diets, while the composition of FM altered little with different diets. The relative abundance of Bacteroidetes and Allobaculum in SIM were negatively correlated with weight gain. There was no significant correlation between FM and weight gain. In conclusion, the community profile of SIM is different from that of feces and susceptible to diet.

Highlights

The different regions of the intestine harbor distinct bacterial communities[10]
There were 696 operational taxonomic units (OTUs) shared in the small intestine mucus (SIM) samples of each group and the number of OTUs unique to the standard diet (STD) group, high-protein diet (HPD) group, high-sugar diet (HSD) group and high-fat diet (HFD) group was 235, 79, 111 and 317, respectively
The results showed that the microflora composition of SIM was markedly different from that of feces; Firmicutes and Proteobacteria were the two most abundant phyla in SIM, accounting for more than 90% relative abundance of the community, and the third abundant phylum was Actinobacteria; fecal microbiota (FM) was dominated by Firmicutes, Bacteroidetes and Proteobacteria

Summary

Introduction

The different regions of the intestine harbor distinct bacterial communities[10]. In humans, Firmicutes and Actinobacteria account for the predominant phyla in duodenal samples, while Bacteroidetes are not detected[11]. Changes in goblet cell and in the chemical composition of intestinal mucus are detected in response to diets and alterations of the normal microbiota. Another study provided evidence that the dietary composition, microbial flora, as well as the interactions between the dietary constituents and microbial flora changed the mucosal architecture and the mucus composition[19] These findings demonstrate that the dietary changes and microbial populations are influential in modifying the amount and proportion of mucins in the small intestine. We investigated (i) the microbial community of in SIM and feces of rats fed various diets by using 16S rRNA sequencing, (ii) the relationship between changes in microbial composition and weight gain in rats, and (iii) the effects of various diets on the small intestinal mucosa

Methods

Results

Conclusion