Neurotransmitter profiles are altered in the gut and brain of mice mono-associated with Bifidobacterium dentium

Berkley Luck, Thomas D. Horvath, Kristen A. Engevik, Wenly Ruan, Sigmund J. Haidacher, Kathleen M. Hoch, Numan Oezguen, Jennifer K. Spinler, Anthony M. Haag, James Versalovic, Melinda A. Engevik

Research output: Contribution to journalArticlepeer-review

10 Scopus citations


Background: Accumulating evidence indicates that the gut microbiota can synthesize neurotransmitters as well as impact host-derived neurotransmitter levels. In the past, it has been challenging to decipher which microbes influence neurotransmitters due to the complexity of the gut microbiota. Methods: To address whether a single microbe, Bifidobacterium dentium, could regulate important neurotransmitters, we examined Bifidobacteria genomes and explored neurotransmitter pathways in secreted cell-free supernatant using LC-MS/MS. To determine if B. dentium could impact neurotransmitters in vivo, we mono-associated germ-free mice with B. dentium ATCC 27678 and examined fecal and brain neurotransmitter concentrations. Results: We found that B. dentium possessed the enzymatic machinery to generate γ-aminobutyric acid (GABA) from glutamate, glutamine, and succinate. Consistent with the genome analysis, we found that B. dentium secreted GABA in a fully defined microbial media and elevated fecal GABA in B. dentium mono-associated mice compared to germ-free controls. We also examined the tyrosine/dopamine pathway and found that B. dentium could synthesize tyrosine, but could not generate L-dopa, dopamine, norepinephrine, or epinephrine. In vivo, we found that B. dentium mono-associated mice had elevated levels of tyrosine in the feces and brain. Conclusions: These data indicate that B. dentium can contribute to in vivo neurotransmitter regulation.

Original languageEnglish (US)
Article number1091
Issue number8
StatePublished - Aug 2021


  • Bifidobacteria
  • GABA
  • Gut microbiome
  • Gut–brain axis
  • LC-MS/MS
  • Neurotransmitters

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology


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