Description:Understanding the role of the gut microbiome in inflammatory and autoimmune diseases requires the identification of microbial molecular effectors and their link to host pathophysiology. Here, we present a framework to identify and characterize novel microbial metabolites in patient samples and to directly link their production to disease-associated microbes. We applied this approach to investigate the spectrum of disease severity and treatment response in ulcerative colitis (UC) using longitudinal metabolite and strain profiles combined with paired plasma profiles.