A Biosensor for Detection of Indole Metabolites

The lack of diverse health-related biosensors limits the progress towards our understanding of how the microbiome metabolism impacts health. Microbially produced indole-3-aldehyde (I3A) has been associated with reducing inflammation in diseases such as ulcerative colitis by stimulating the aryl hydrocarbon receptor (AhR) pathway. We mined the protein database for gut microbiome metabolites sensors and developed a biosensor for I3A. We engineered E. coli embedded with a single plasmid carrying a chimeric two-component system that detects I3A. Our I3A receptor characterization identified residues that contribute to the sensors high specificity in a range of 0.1-10 {micro}M. The I3A biosensor opens the door to sensing indole metabolites produced at the host-microbe interface and provides new parts for synthetic biology applications.