Gut Microbiome and Metabolome Profiles Associated with High-Fat Diet in Mice

Abstract

Obesity can be caused by microbes producing metabolites; it is thus important to determine the correlation between gut microbes and metabolites. This study aimed to identify gut microbiota-metabolomic signatures that change with a high-fat diet and understand the underlying mechanisms. To investigate the profiles of the gut microbiota and metabolites that changed after a 60% fat diet for 8 weeks, 16S rRNA gene amplicon sequencing and gas chromatography-mass spectrometry (GC-MS)-based metabolomic analyses were performed. Mice belonging to the HFD group showed a significant decrease in the relative abundance of Bacteroidetes but an increase in the relative abundance of Firmicutes compared to the control group. The relative abundance of Firmicutes, such as Lactococcus, Blautia, Lachnoclostridium, Oscillibacter, Ruminiclostridium, Harryflintia, Lactobacillus, Oscillospira, and Erysipelatoclostridium, was significantly higher in the HFD group than in the control group. The increased relative abundance of Firmicutes in the HFD group was positively correlated with fecal ribose, hypoxanthine, fructose, glycolic acid, ornithine, serum inositol, tyrosine, and glycine. Metabolic pathways affected by a high fat diet on serum were involved in aminoacyl-tRNA biosynthesis, glycine, serine and threonine metabolism, cysteine and methionine metabolism, glyoxylate and dicarboxylate metabolism, and phenylalanine, tyrosine, and trypto-phan biosynthesis. This study provides insight into the dysbiosis of gut microbiota and metabolites altered by HFD and may help to understand the mechanisms underlying obesity mediated by gut microbiota.

Keywords: gut microbiota; high-fat diet; metabolite; obesity.

Figure 1

(A) Body weight changes in the control group and high fat diet (HFD) group. (B) Total cholesterol (TCHO-P III) in serum samples. (C) Serum glucose (GLU-P III) levels. (D) Weight of the adipose tissue. **, p < 0.01; ***, p < 0.001.

Figure 2

(A) Beta diversity analysis of the control and HFD groups. (B) Alpha diversity analysis of the control and HFD groups. (C) Comparison of microbiota composition at the phylum level. (D) Relative abundance of Bacteroidetes and Firmicutes. (E) Cladogram, generated using the linear discriminant analysis effect size (LEfSe) method, shows the phylogenetic distribution of microbes that are associated with the control and HFD groups. Taxonomic levels of phylum, class, and order are labelled, while family and genus are abbreviated. Plots were represented using LEfSe. Colored regions/branches indicate differences in the bacterial population structure between the control and HFD groups. Regions in green indicate clades that were enriched in the HFD group compared to those in the control group, while regions in red indicate clades that were enriched in the control group as opposed to those in the HFD group. ***, p < 0.001.

Figure 3

Box plots of significantly different microorganisms at the genus level in the guts of the HFD and control groups. The p-values were obtained using Mann–Whitney U tests. *, p < 0.05; **, p < 0.01. A false discovery rate of 5% was applied to all tests to correct for multiple testing.

Figure 4

Supervised partial least squares discriminant analysis (PLS−DA) score plot derived from the GC−MS data of (A) serum and (B) fecal samples of HFD and control groups. Permutation tests with 200 iterations were performed to validate the goodness of fit of the original model.

Figure 5

Box plots of significantly different metabolites in (A) serum and (B) fecal samples of the HFD and control groups. *, p < 0.05; **, p < 0.01; ***, p < 0.001. A false discovery rate of 5% was applied to all tests to correct for multiple testing.

Figure 6

The heat map shows correlation between the identified metabolites and microbiota. R−values of 0.7 or more are highlighted with white borders. A false discovery rate of 5% was applied to all tests to correct for multiple testing.