Tryptophan metabolites in fecal samples from healthy humans

Tryptophan metabolites (TMs) of bacterial origin are increasingly recognized as important signaling molecules among gut microbiota and with the host. However, few reports exist for fecal TM levels in healthy humans, and reported levels vary widely. Further, the specific bacterial species producing TMs and the combinations of fecal TMs in healthy individuals are not well known. Our research combines 16S and whole genome shotgun sequencing of gut bacteria with a sensitive method (LC/MS) for measuring TMs and a reported method to predict which species are likely TM contributors. To our knowledge, this combination of analyses has not been reported elsewhere and will add significantly to the existing literature. Understanding TM levels and their sources in the healthy intestine are fundamental to elucidating how TMs contribute to maintaining homeostasis. Such knowledge of gut microbiota and their metabolic products will inform novel strategies to maintain intestinal health and prevent or treat dysbioses.