Nutritional intervention trial of yeast mannans derived from baker's yeast enriches Bacteroides and Parabacteroides with concurrent reduction of Klebsiella pneumoniae
Abstract
IntroductionSupplementation with a yeast cell wall fraction rich in mannans is well tolerated in adults without gastrointestinal disease; however, limited research has examined its selective utilization by the gut microbiota and associated health benefits. The aim of this analysis was to investigate the specific effects of yeast mannans on the composition and metabolic function of the gut microbiota.MethodsFecal samples from an open-label study of adults consuming 15 g of yeast mannans per day were profiled for fecal microbiota composition using whole metagenome sequencing, and fecal and urine metabolomics were analyzed by direct infusion and liquid chromatography-tandem mass spectrometry (DI-MS/MS and LC-MS/MS).ResultsDifferential abundance testing identified 46 species whose relative abundances increased with the yeast mannan intervention, primarily in the genera Bacteroides and Parabacteroides. Thomasclavelia spiroformis showed the largest fold increase. Four species decreased in relative abundance, with a greater-than-2-fold decrease in Klebsiella pneumoniae, with 45% of participants showing no detection following the yeast mannan intervention. Minor metabolomic changes were noted, including increased urinary excretion of N-acetylalanine, alanine, and caproic acid, and decreases in fecal concentrations of ether-linked phosphatidylcholines C36:4 and C40:1.DiscussionYeast mannan supplementation selectively enriched several Bacteroides and Parabacteroides, saccharolytic commensals that may outcompete Klebsiella pneumoniae, an opportunistic pathobiont capable of causing extraintestinal infections.
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BibTeX
@article{moreno2026nutritional,
title = {{Nutritional intervention trial of yeast mannans derived from baker's yeast enriches Bacteroides and Parabacteroides with concurrent reduction of Klebsiella pneumoniae}},
author = {Melissa L. Moreno and Diana H. Taft and Thomas A. Tompkins and Wendy J. Dahl},
journal = {Frontiers in Microbiology},
year = {2026},
month = oct,
doi = {10.3389/fmicb.2026.1958679},
url = {https://www.frontiersin.org/articles/10.3389/fmicb.2026.1958679},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Nutritional intervention trial of yeast mannans derived from baker's yeast enriches Bacteroides and Parabacteroides with concurrent reduction of Klebsiella pneumoniae
AU - Melissa L. Moreno
AU - Diana H. Taft
AU - Thomas A. Tompkins
AU - Wendy J. Dahl
PY - 2026
DA - 2026/10/30
JO - Frontiers in Microbiology
DO - 10.3389/fmicb.2026.1958679
UR - https://www.frontiersin.org/articles/10.3389/fmicb.2026.1958679
AB - IntroductionSupplementation with a yeast cell wall fraction rich in mannans is well tolerated in adults without gastrointestinal disease; however, limited research has examined its selective utilization by the gut microbiota and associated health benefits. The aim of this analysis was to investigate the specific effects of yeast mannans on the composition and metabolic function of the gut microbiota.MethodsFecal samples from an open-label study of adults consuming 15 g of yeast mannans per day were profiled for fecal microbiota composition using whole metagenome sequencing, and fecal and urine metabolomics were analyzed by direct infusion and liquid chromatography-tandem mass spectrometry (DI-MS/MS and LC-MS/MS).ResultsDifferential abundance testing identified 46 species whose relative abundances increased with the yeast mannan intervention, primarily in the genera Bacteroides and Parabacteroides. Thomasclavelia spiroformis showed the largest fold increase. Four species decreased in relative abundance, with a greater-than-2-fold decrease in Klebsiella pneumoniae, with 45% of participants showing no detection following the yeast mannan intervention. Minor metabolomic changes were noted, including increased urinary excretion of N-acetylalanine, alanine, and caproic acid, and decreases in fecal concentrations of ether-linked phosphatidylcholines C36:4 and C40:1.DiscussionYeast mannan supplementation selectively enriched several Bacteroides and Parabacteroides, saccharolytic commensals that may outcompete Klebsiella pneumoniae, an opportunistic pathobiont capable of causing extraintestinal infections.
SN - 1664-302X
ER -