Xenometabolomics reveals metabolic functional guilds unique to specific inulin subtypes in human gut microbiota cultures

Dietary fibers can convey positive health effects, but the full suite of mechanisms and fiber type differences remains to be elaborated. Historically, most discussions have focused on the impact of fibers in promoting lower gut bacterial fermentation, leading to the generation of short-chain fatty acids (especially butyrate) and promoting growth of specific microbes. That said, health effects associated with dietary fiber are generally shared across diverse individuals harboring disparate gut microbial species, and it is increasingly appreciated that xenometabolites derived from microbial metabolism number in the thousands. In the current report, we applied metabolomics characterization to human stool cultures incubated with six structurally distinct inulin fibers. The results indicate that distinct, fiber-specific metabolite signatures manifest despite quite diverse bacterial community structures across donors. Such outcomes point to the existence of metabolic functional guilds that shape the metabolite landscape-and likely the unique bioactive characteristics-across dietary fiber types.