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Nutritional Microbiology/Microbiome/Microbiome Nutrition (Poster Session)

(P19-029-25) Characterization of Microbial Glutamate Biosynthesis in the Large Intestine and Its Response to Prebiotic Oligosaccharides

Sunday, June 1, 2025
12:45 PM - 1:45 PM ET
Location: Poster Board B-71

    Presenting Author(s)

  • IM

    Islam Mabrouk, Ph.D candidate

    Graduate student
    University of Minnesota
    St. Paul, Minnesota, United States

    • Co-Author(s)

  • YM

    Yiwei Ma, PhD

    PhD Student
    University of Minnesota
    Saint Paul, Minnesota, United States

  • CC

    Chi Chen, Dr

    Associate Professor
    University of Minnesota
    St Paul, Minnesota, United States

Disclosure(s):
Islam Mabrouk, Ph.D candidate: No relevant financial relationship(s) with ineligible companies to disclose.


Objectives: Gut microbes are known to conduct de novo synthesis of amino acids, but the contribution of this metabolic activity to the luminal metabolome was not well understood. This study aims to compare the amino acid profile of the large intestine digesta samples with the profile of their small intestine counterparts and then examine the effects of prebiotics on the profile in mice.

Methods: Animal experiment 1: Digesta samples from duodenum, jejunum, ileum, cecum, and colon were collected from 6 male C57BL/6 mice fed AIN93G diet for 7 days. Animal experiment 2: Total 32 male C57BL/6 mice in 4 treatment groups were fed the AIN93 diets containing 0, 0.2%, 1%, and 5% of mannose oligo-saccharide (MOS), respectively, for 6 weeks, and the digesta samples across the intestinal tract were collected. All digesta samples were derivatized by dansyl chloride and then measured by the liquid chromatography-mass spectrometry analysis for the quantification of free amino acids, multivariate modeling, and statistical analysis, including ANOVA and t-test.

Results: The comparisons of the digesta sample across the intestinal tract showed the different compositions of free amino acids between the small intestine and the large intestine. Interestingly, glutamate was greatly enriched in the cecum and colon, indicating active de novo glutamate biosynthesis. Moreover, the MOS feeding dose-dependently increased glutamate as well as α-ketoglutarate, which is the precursor in microbial glutamate biosynthesis, in the large intestine.

Conclusions: De novo glutamate biosynthesis is actively present in the large intestine of mice and highly modulable by prebiotics. All these observations warrant further investigations on the metabolic pathways and gut microbes responsible for its biosynthesis.

Funding Sources: Minnesota Agricultural Experiment Station project MIN-18-125

Egyptian Ministry of Higher Education