Programming animal physiology and behaviors through engineered bacteria

A central goal of synthetic biology is to predictably and efficiently reprogram living systems to perform computations and carry out specific biological tasks. Although there have been many advances in the bio-computational design of living systems, these advances have mainly been applied to microorganisms or cell lines; programming animal behavior and altering animal physiology remain challenges for synthetic biology because of the system complexity. Here, we present a bacteria-animal symbiont system in which engineered bacteria recognize external signals and modulate animal gene expression, twitching behavior, and fat metabolism through RNA interference. By using genetic circuits in bacteria to control RNA expression, we programmed the physiology and behavior of the model animal with logic gates. We anticipate that engineered bacteria can be used more extensively to program animal metabolism and behaviors for agricultural, therapeutic, and basic science applications.