Bacteria Engineered to Produce Serotonin Modulate Host Intestinal Physiology.

Bacteria in the gastrointestinal tract play a crucial role in intestinal motility, homeostasis, and dysfunction. Unraveling the mechanisms by which microbes impact the host poses many challenges due to the extensive array of metabolites produced or metabolized by bacteria in the gut. Here, we describe the engineering of a gut commensal bacterium, Nissle 1917, to biosynthesize the human metabolite serotonin for examining the effects of microbially produced biogenic amines on host physiology.