Sean Davies had a problem to solve: If you genetically modify enteric bacteria to make them more healthful, how can you quickly check to see if they’re happily growing away inside your experimental rat? The solution he chose could represent the pinnacle of scientific achievement in its own right – he incorporated bioluminescence into the same bacteria. Those rats that were successfully colonized by the modified E. coli could be detected at a glance – because their poop now glowed in the dark.

Sean did not start out to create the next GM novelty item. Working in the Vanderbilt Department of Pharmacology and with collaborators at Texas A&M and CNRS in France, he recognized that not all gut bacteria are created equal. Many recent studies have demonstrated that the gut microbiota can predispose an individual to metabolic disorders, including obesity. So why not engineer a gut microbe specifically to be a health-promoting bug?

Four weeks after ingesting a dose of these high-tech probiotic bacteria, lab rats on a high fat diet gained 20% less weight than their controls, who not only got fat, but also had boring bowel movements. Taking a cue from the field of endocannabinoids, the lipid substances that are your body’s own version of THC, the researchers surmised that a genetically modified gut microbe could be designed to produce a normal signal of satiety. The gene for N-Acylethanolamine (NAE) synthesis was transfected into the normal human commensal E. coli N1917, along with the luciferase gene so it was easy to check on how these new bugs were thriving. NAE works in the gut to induce a feeling of fullness and anorexia, normally in response to a high fat meal.

A preliminary report of the study was presented on November 4, 2013 in San Juan, Puerto Rico at the 13^th International Conference on Bioactive Lipids. Sean hopes to publish a full description of these exciting results in the Journal of Clinical Investigation, no doubt to glowing reviews.