Project Summary Despite impressive developments designing robust genetic circuits into bacteria, progress on the application of these approaches in complex environments has only recently been made and is still a general challenge. This is further complicated by issues arising from the release of engineered microbes into the environment, which may constitute ecological hazards. The primary goal of this project is to understand the interplay between environmental signals and synthetic genetic circuits. I will first design sensors that can probe and report on the local inflammatory conditions inside the intestine, which could ultimately be used as diagnostics. I will also design sensors that can detect environmental conditions indicative of being outside the gut (e.g., oxygen or drop in temperature) and will trigger a kill switch that will cause any released bacteria to self-destruct. These methods will quantitatively assess how environmental signals regulate engineered pathways as well as facilitate the safe application of engineered organisms into real-world contexts. The secondary goal is to create a foundation from which novel diagnostics and therapeutics can nondestructively function within the gut: a variable environment that is difficult to access. The gut microbiota maintains an intimate symbiotic relationship with the host; influencing multiple aspects of health, disease, and metabolism. Perturbations to its homeostasis can result in inflammatory and autoimmune diseases, transfer of antibiotic resistance, obesity and diabetes, inflammatory bowel disease, pathogenic infections, and cancer. Understanding the cross-talk between the host and microbiome will be invaluable for basic and translational research. Toward these ends, I will: 1. Understand signals of inflammation in the gut with bioengineered sensors. 2. Evaluate the environmental conditions necessary to eliminate engineered E. coli in a gut-on-a-chip device. 3. Test the impact of variable environmental stimuli on endogenous and abundant intestinal commensals. If implemented, this strategy could serve as an early detection system for infection, inflammatory bowel disease, and cancer. Using endogenous bacteria for safe, instantaneous, site-specific, and precise delivery of therapeutic compounds in response to environmental change could be tremendously advantageous for disease treatment and long-term health.