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Updated: Aug 31, 2025

Investigating the Alleviating Effects of Bacillus cereus Administration on Colitis through Gut Microbiota Modulation
Published on: July 27, 2022
D-Tryptophan suppresses enteric pathogen and pathobionts and prevents colitis by modulating microbial tryptophan
Natsumi Seki1,2, Tatsuki Kimizuka1,2, Monica Gondo1,2
1Research Center for Drug Discovery, Faculty of Pharmacy and Graduate School of Pharmaceutical Sciences, Keio University, Tokyo 105-8512, Japan.
Abstract:
D-Amino acids (D-AAs) have various functions in mammals and microbes. D-AAs are produced by gut microbiota and can act as potent bactericidal molecules. Thus, D-AAs regulate the ecological niche of the intestine; however, the actual impacts of D-AAs in the gut remain unknown. In this study, we show that D-Tryptophan (D-Trp) inhibits the growth of enteric pathogen and colitogenic pathobionts. The growth of Citrobacter rodentium in vitro is strongly inhibited by D-Trp treatment. Moreover, D-Trp protects mice from lethal C. rodentium infection via reduction of the pathogen. Additionally, D-Trp prevents the development of experimental colitis by the depletion of specific microbes in the intestine. D-Trp increases the intracellular level of indole acrylic acid (IA), a key molecule that determines the susceptibility of enteric microbes to D-Trp. Treatment with IA improves the survival of mice infected with C. rodentium. Hence, D-Trp could act as a gut environmental modulator that regulates intestinal homeostasis.
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