Harnessing flavonoids to control probiotic function: <i>in situ</i> application of a naringenin-responsive genetic circuit

Engineering probiotics is a rapidly advancing field in synthetic biology. Genetic circuits, which enable precise and predictable control of microbial phenotypes, are central to this effort. Leveraging natural, plant-based compounds like flavonoids to control gene expression offers a promising strategy for developing next-generation probiotics with enhanced capabilities. This study demonstrates the activity of a flavonoid-responsive genetic circuit during host-microbe interactions. The findings provide a foundation for using beneficial compounds like naringenin as inputs to drive desired phenotypes <i>in vivo</i>. In addition, this work expands the range of genetic circuit inputs, facilitating the design of more sophisticated, multi-input systems for probiotic engineering.