Summary The purpose of this proposal is to provide equipment support to our currently funded NIGMS (R35GM118159) research project. Despite the possibility that the gut microbiome may represent a critical and readily modifiable component of human biology, the contribution of the gut microbiota to health, disease risk, and response to therapy remains largely undefined. The overall goal of the parent grant is to understand the principles, mechanisms, and processes that shape the interaction between gut microbial communities and their hosts. Our strategy is to combine anaerobic microbial genetics and high-throughput mass spectrometry with gnotobiotic (germfree and ex-germfree) mouse models to dissect these interactions. Gnotobiotic mice are the central experimental system that we're using to conduct these studies. These animals, which are maintained in sterile flexible plastic isolators or individually ventilated cages, lack any bacteria or other microbes. They can then be compared to conventional animals that carry a normal microbiome, or colonized with individual bacterial species, mutants of these species, or otherwise engineered strains in which gene expression can be precisely controlled. Although we have made significant progress in the project (12 papers supported by GM118159), the main limitation is our restricted access to the steam sterilizer (autoclave) equipment that is used to prepare every experiment. This limitation also reduces our ability to engage in collaborations with multiple NIGMS-funded researchers at the university who provide letters of support for this application. For these reasons, we request funds to partially support the purchase of a steam sterilizer for gnotobiotics. The cost of this project is also being significantly supported by the university.