Engineered bacteria titrate hydrogen sulfide and induce concentration-dependent effects on the host in a gut microphysiological system.

Hydrogen sulfide (H2S) is a gaseous microbial metabolite whose role in gut diseases is debated, with contradictory results stemming from experimental difficulties associated with accurate dosing and measuring H2S and the use of model systems that do not accurately represent the human gut environment. Here, we engineer Escherichia coli to titrate H2S across the physiological range in a gut microphysiological system (chip) supportive of the co-culture of microbes and host cells. The chip is engineered to maintain H2S gas tension and enables visualization of co-culture in real time with confocal microscopy. Engineered strains colonize the chip and are metabolically active for 2 days, during which they produce H2S across a 16-fold range and induce changes in host gene expression and metabolism in an H2S-concentration-dependent manner. These results validate a platform for studying the mechanisms underlying microbe-host interactions by enabling experiments that are infeasible with current animal and in vitro models.

Engineered bacteria titrate hydrogen sulfide and induce concentration-dependent effects on host in a gut microphysiological system.

Hydrogen sulfide (H2S) is a gaseous microbial metabolite whose role in gut diseases is debated, largely due to the difficulty in controlling its concentration and the use of non-representative model systems in previous work. Here, we engineered E. coli to titrate H2S controllably across the physiological range in a gut microphysiological system (chip) supportive of the co-culture of microbes and host cells. The chip was designed to maintain H2S gas tension and enable visualization of co-culture in real-time with confocal microscopy. Engineered strains colonized the chip and were metabolically active for two days, during which they produced H2S across a sixteen-fold range and induced changes in host gene expression and metabolism in an H2S concentration-dependent manner. These results validate a novel platform for studying the mechanisms underlying microbe-host interactions, by enabling experiments that are infeasible with current animal and in vitro models.