This project will investigate the role of gut microorganisms in controlling human health by focusing on microorganism interactions with the gut sugar polymer mucin. Mucin is a component of gut mucus and is very important for maintaining the integrity of the gut barrier between microorganisms and the human host. The human body needs beneficial microorganisms to help digest food and to develop the immune system, but it must keep both beneficial and pathogenic, or disease-causing, bacteria out of the bloodstream. Previous research indicates that beneficial and pathogenic bacteria secrete products to change the oxidation/reduction state of mucin. Therefore, this work will use miniaturized models of synthetic gut bacterial communities to explore gut modifications by beneficial and pathogenic bacteria in the presence of a collection of bacteria from healthy mice. The approach includes an electrochemical mucin-on-chip model and elimination of pathogens using engineered, beneficial bacteria. This work will enhance the understanding of how human health is dependent on a healthy gut microbial community and identify methods to correct gut communities that are causing disease. This project aims to investigate the uncharacterized role of invasive, pathogenic Escherichia coli (E. coli) strains in the distribution of mucin, a layer of heavily glycosylated proteins essential for maintaining the integrity of the gut barrier, and its involvement in inflammatory bowel diseases (IBD). Recent