Project Summary: Resident microbiota profoundly influence physiologic responses in many organs and are linked to a number of inflammatory (IBD, asthma, NASH, atherosclerosis), metabolic (diabetes, metabolic syndrome), neoplastic (colon, breast and pancreatic cancer) and behavioral (depression, anorexia, autism) disorders. However, the functional consequences and the primary vs. secondary nature of these compositional changes and the role of individual bacterial species and combinations remain unknown. These functional properties can be mechanistically addressed in gnotobiotic mice by precisely manipulating the microbiota by selectively colonizing germ-free (GF) normal and genetically- engineered inbred mice with single or multiple resident or pathogenic bacterial, viral or fungal species. Alternatively, transplants can transfer fecal or luminal material derived from normal or diseased human or experimental animal models to GF mice to explore functional properties of dysbiotic complex bacterial communities. However, the microbial heterogeneity in human specimens and the clinical heterogeneity within patients with complex diseases are enormous, so the source of materials used to colonize the ex-GF mice greatly affect results. Thus, an important unmet need is a readily accessible source of fully characterized complex intestinal microbiota and bacterial strains to colonize gnotobiotic mice. We hypothesize that transferring fully characterized pooled fecal transplants and bacterial strains into gnotobiotic inbred mice will yield highly reproducible results and stable phenotypes in recipient mice. Aim: Develop and characterize pooled complex human and murine microbial communities and bacteria strains with validated in vivo functions to create a repository that can be used to achieve reproducible results in gnotobiotic studies. This resource will be widely available to investigators using GF mice from our gnotobiotic facility and the greater research community to improve rigor and reproducibility of experimental results and yield widely accessible data to guide further mechanistic studies