Microbially conjugated bile acids differentially affect the lifecycle and pathogenesis of Clostridioides difficile
- 1NC State University
Abstract
Clostridioides difficile is a Gram-positive bacterium that causes C. difficile infection (CDI). In healthy adults, it has been proposed that the gut microbiota provides colonization resistance against C. difficile by competition through nutrient limitation and antagonism through secondary bile acid metabolism, the latter of which is mediated by the deconjugation of host-derived bile acids with bacterial bile salt hydrolases (BSH). Recently, BSHs have also shown an ability to reconjugate non-canonical (i.e., not glycine or taurine) amino acids to sterol cores, resulting in novel microbially conjugated bile acids (MCBAs). MCBAs have been associated with the resolution of recurrent CDI, though the mechanism underlying these effects are not well understood. To address this gap, we synthesized 36 MCBAs with nine amino acids (cysteine, isoleucine, leucine, phenylalanine, proline, serine, tryptophan, tyrosine, and valine) conjugated to the primary and secondary bile acids found in the human gut (CA, DCA, CDCA, and LCA) and tested their impact on various stages of C. difficiles lifecycle including bacterial outgrowth, membrane integrity, sporulation, and toxin activity. We show that BSH-mediated amidation of bile acid sterol cores can either increase or decrease inhibitory effects on C. difficile in an amino acid-dependent manner. For example, serine MCBAs enhanced C. difficiles ability to grow in otherwise inhibitory bile acid concentrations, increased spore production, and elevated toxin activity. Tryptophan MCBAs increased inhibition. By demonstrating these variable effects, our work clarifies the molecular determinants of MCBA activity and highlights specific MCBAs as promising targets for the development of C. difficile microbial-based therapeutics.
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BibTeX
@misc{theriot2026microbially,
title = {{Microbially conjugated bile acids differentially affect the lifecycle and pathogenesis of Clostridioides difficile}},
author = {C. M. Theriot and S. W. Hamacher and N. K. Nandwana and N. S. Lyons and A. S. Gancz and C. E. Perkins and B. Cheng and E. Gentry},
howpublished = {bioRxiv},
year = {2026},
month = nov,
doi = {10.64898/2026.11.05.764496},
url = {https://www.biorxiv.org/content/10.64898/2026.11.05.764496v1},
note = {CC BY-NC-ND},
}
RIS
TY - UNPB
TI - Microbially conjugated bile acids differentially affect the lifecycle and pathogenesis of Clostridioides difficile
AU - C. M. Theriot
AU - S. W. Hamacher
AU - N. K. Nandwana
AU - N. S. Lyons
AU - A. S. Gancz
AU - C. E. Perkins
AU - B. Cheng
AU - E. Gentry
PY - 2026
DA - 2026/11/05
PB - bioRxiv
DO - 10.64898/2026.11.05.764496
UR - https://www.biorxiv.org/content/10.64898/2026.11.05.764496v1
AB - Clostridioides difficile is a Gram-positive bacterium that causes C. difficile infection (CDI). In healthy adults, it has been proposed that the gut microbiota provides colonization resistance against C. difficile by competition through nutrient limitation and antagonism through secondary bile acid metabolism, the latter of which is mediated by the deconjugation of host-derived bile acids with bacterial bile salt hydrolases (BSH). Recently, BSHs have also shown an ability to reconjugate non-canonical (i.e., not glycine or taurine) amino acids to sterol cores, resulting in novel microbially conjugated bile acids (MCBAs). MCBAs have been associated with the resolution of recurrent CDI, though the mechanism underlying these effects are not well understood. To address this gap, we synthesized 36 MCBAs with nine amino acids (cysteine, isoleucine, leucine, phenylalanine, proline, serine, tryptophan, tyrosine, and valine) conjugated to the primary and secondary bile acids found in the human gut (CA, DCA, CDCA, and LCA) and tested their impact on various stages of C. difficiles lifecycle including bacterial outgrowth, membrane integrity, sporulation, and toxin activity. We show that BSH-mediated amidation of bile acid sterol cores can either increase or decrease inhibitory effects on C. difficile in an amino acid-dependent manner. For example, serine MCBAs enhanced C. difficiles ability to grow in otherwise inhibitory bile acid concentrations, increased spore production, and elevated toxin activity. Tryptophan MCBAs increased inhibition. By demonstrating these variable effects, our work clarifies the molecular determinants of MCBA activity and highlights specific MCBAs as promising targets for the development of C. difficile microbial-based therapeutics.
ER -