Metabolomic analysis of human fecal microbiota: a comparison of feces-derived communities and defined mixed communities.

The extensive impact of the human gut microbiota on its human host calls for a need to understand the types of communication that occur among the bacteria and their host. A metabolomics approach can provide a snapshot of the microbe-microbe interactions occurring as well as variations in the microbes from different hosts. In this study, metabolite profiles from an anaerobic continuous stirred-tank reactors (CSTR) system supporting the growth of several consortia of bacteria representative of the human gut were established and compared. Cell-free supernatant samples were analyzed by 1D 1H nuclear magnetic resonance (NMR) spectroscopy, producing spectra representative of the metabolic activity of a particular community at a given time. Using targeted profiling, specific metabolites were identified and quantified on the basis of NMR analyses. Metabolite profiles discriminated each bacterial community examined, demonstrating that there are significant differences in the microbiota metabolome between each cultured community. We also found unique compounds that were identifying features of individual bacterial consortia. These findings are important because they demonstrate that metabolite profiles of gut microbial ecosystems can be constructed by targeted profiling of NMR spectra. Moreover, examination of these profiles sheds light on the type of microbes present in the gut and their metabolic interactions.