Monosodium L-Glutamate and Dietary Fat Differently Modify the Composition of the Intestinal Microbiota in Growing Pigs

Abstract

Background: The Chinese have been undergone rapid transition to a high-fat diet-consuming lifestyle, while monosodium L-glutamate (MSG) is widely used as a daily food additive. It has been reported that fat alters the composition of intestinal microbiota. However, little information is available on the effects of oral MSG on intestinal microbiota, and no study was done focusing on the interaction effect of fat and MSG with respect to intestinal microbiota. The present study thus aimed to determine the effects of MSG and/or fat on intestinal microbiota, and also to identify possible interactions between these two nutrients.

Methods: Four iso-nitrogenous and iso-caloric diets were provided to growing pigs. The microbiota from jejunum, ileum, cecum, and colon were analyzed.

Results: Our results show that both MSG and fat clearly increased the intestinal microbiota diversity. MSG and fat modified the composition of intestinal microbiota, particularly in the colon. Both MSG and fat promoted the colonization of microbes related to energy extraction in gastrointestinal tract via different ways. MSG promoted the colonization of Faecalibacterium prausnitzii and Roseburia, while fat increased the percentage of Prevotella in colon and other intestinal segments.

Conclusion: Our results will help to understand how individual or combined dietary changes modify the microbiota composition to prevent obesity.

Fig. 1

Dietary supplementation of MSG and fat can influence the main components in muscle of growing pigs (n = 4). A Crude protein, B dry matter, C fat.

Fig. 2

PCR-DGGE profiles of intestinal contents using the following primer sets of intestinal microbiota: HAD-1 GC and HAD-2 (35-65% DGGE). The clustering dendrogram was generated with Quantity One software using the UPGMA method. 1) Holdemaniafiliformis, 2) Escherichia fergusonii, 3) Ruminococcuscallidus, 4) Clostridium hylemonae, 5) Allisonellahistaminiformans, 6) Actinobacillusarthritidis, 7) Actinobacillus minor, 8) Clostridium chauvoei, 9) Clostridium chauvoei, 10) Clostridium chauvoei, 11) Clostridium glycolicum, 12) Shigellaflexneri, 13) Salmonella enterica subsp., 14) Roseburiafaecis, 15) Pseudomonas geniculate, 16) Enterobacter cloacae, 17) Lactobacillus taiwanensis.

Fig. 3

Corresponding PCA analysis of intestinal microbiota. 1) BD-ileum, 2) HF-ileum, 3) BDM-ileum, 4) HFM-ileum, 5) BD-cecum, 6) HF-cecum, 7) BDM-cecum, 8) HFM-cecum, 9) BD-colon, 10) HF-colon, 11) BDM-colon, 12) HFM-colon.

Fig. 4

Dietary MSG and fat influence the ratio of Firmicutes/Bacteroidetes in the gastrointestinal tract of growing pigs (n = 4).