Engineering bacterial thiosulfate and tetrathionate sensors for detecting gut inflammation

Abstract

There is a groundswell of interest in using genetically engineered sensor bacteria to study gut microbiota pathways, and diagnose or treat associated diseases. Here, we computationally identify the first biological thiosulfate sensor and an improved tetrathionate sensor, both two‐component systems from marine Shewanella species, and validate them in laboratory Escherichia coli . Then, we port these sensors into a gut‐adapted probiotic E. coli strain, and develop a method based upon oral gavage and flow cytometry of colon and fecal samples to demonstrate that colon inflammation (colitis) activates the thiosulfate sensor in mice harboring native gut microbiota. Our thiosulfate sensor may have applications in bacterial diagnostics or therapeutics. Finally, our approach can be replicated for a wide range of bacterial sensors and should thus enable a new class of minimally invasive studies of gut microbiota pathways. image A sensor bacterium that uses a novel two‐component signaling system is engineered to detect thiosulfate and colon inflammation. This work suggests thiosulfate as a novel biomarker of colon inflammation and demonstrates the potential of engineered bacteria in disease diagnostics. Novel two‐component system sensors of thiosulfate and tetrathionate from marine Shewanella species are identified computationally. Both sensors are characterized in laboratory Escherichia coli and then ported to the gut‐adapted probiotic strain Nissle 1917. A flow cytometry protocol is developed for identifying the engineered bacteria in the colon contents or feces of mice with intact microbiota. The thiosulfate sensor has elevated output in inflamed mice, suggesting thiosulfate as a novel biomarker of inflammation.