Imbalanced dietary intake alters the colonic microbial profile in growing rats

Abstract

An imbalanced dietary intake is associated with alteration of intestinal ecosystem. We investigated the impact of imbalanced diets on colonic microbiota, concentrations of short chain fatty acid in colonic digesta and serum immunoglobulins (Igs) of growing rats. Compared to the control diet, consuming diets high in fat, sucrose, or processed meat, or low in iron, increased the abundance of the pathogenic bacteria such as Clostridium, Escherichia coli, and Salmonella species, and decreased the beneficial bacteria, like Bifidobacteria, Lactobacillus, Akkermansia, Phascolarctobacterium, Alistipes, and butyrate producing species of bacteria in the colon of growing rats. The heatmap of metagenomics indicated that each group was separated into distinct clusters, and the ID group in particular, showed significantly (P < 0.01) reduced alpha diversity of colonic microbiota in comparison to the control group. All experimental groups showed significantly (P < 0.05 or P < 0.01) decreased concentration of acetate and butyrate in the colonic digesta and lower levels of serum IgG or IgA, compared to the control. These results indicated that the imbalanced dietary intake negatively altered intestinal ecosystem and immunity.

Fig 1. PCR-DGGE bands from pooled DNA samples (n = 12) of colonic digesta used in DNA sequencing for identification of bacteria.

Arrows indicate the bands subject to DNA sequencing. M, marker; A, control; B, high fat; C, high sucrose; D, iron deficiency; E, processed meat.

Fig 2. Comparison of the gut microbiota at genus level between control and experimental groups.

(A) heatmap, (B) relative abundance, (C) alpha diversity. CON, control; HF, high fat; HS, high sucrose; ID, iron deficiency; PM, processed meat. Values are expressed as mean ± SEM. Statistical significance compared to control was accepted at *P < 0.05, **P < 0.01.

Fig 3. Concentration of short chain fatty acids in the colonic digesta according to dietary treatments.

HF, high fat; HS, high sucrose; ID, iron deficiency; PM, processed meat. Values are expressed as mean ± SEM. Statistical significance compared to control was accepted at *P < 0.05.

Fig 4. Immunoglobulin levels in the serum of growing rats with different dietary treatments.

(A) IgG, (B) IgM, (C) IgA. HF, high fat; HS, high sucrose; ID, iron deficiency; PM, processed meat. Values are expressed as mean ± SEM. Statistical significance compared to control was accepted at *P < 0.05, **P < 0.01.