Engineering <i>Escherichia coli</i> for Conversion of Dietary Isoflavones in the Gut

Introducing metabolic pathways to the gut is important to tailor the biochemical components ultimately absorbed by the host. Given identical diets, hosts possessing different consortia of gut bacteria can exhibit distinct health outcomes regulated by metabolic capabilities of the gut microbiota. The disparate competency of the population to metabolize isoflavones, such as dietary daidzein, has shown health benefits for those individuals possessing gut bacteria capable of producing equol from daidzein-rich diets. To begin addressing health inequalities due to gut metabolic pathway deficiencies, we developed a probiotic that allows metabolism of isoflavones to provide a gut phenotype paralleling that of natural equol producers. Toward this goal, we engineered Escherichia coli to produce the enzymes necessary for conversion of daidzein to equol, and as demonstrated in a murine model, these bacteria enabled elevated serum equol levels to dietary daidzein, thus serving as a starting point for more sophisticated systems.