(228bm) Engineering Short-Chain Fatty Acid Production in Probiotic Bacteria

Short-chain fatty acids (SCFAs), especially butyric acid, have many roles in the human gut, affecting immunomodulation, cell differentiation and apoptosis. In addition, butyrate is the preferred carbon source for colon cells. Butyrate is normally produced in the colon by butyrogenic anaerobic bacteria that respond to dietary fiber or other prebiotics. However, diets rich in low-fiber, highly processed foods can result in low gut butyrate levels, which can lead to inflammation and other bowel diseases. In these disease states, populations of butyrogenic bacteria are also decreased.

Using a CRISPR-Cas based genome engineering method, we have engineered a model probiotic organism, E. coli Nissle 1917, to produce butyrate in both aerobic and anaerobic culture conditions. Further genetic optimization has been completed to increase anaerobic butyrate production, mimicking conditions in the gut. Additionally, to facilitate a high-throughput approach to butyrate production, we have developed a biosensor that responds to intracellular butyrate concentrations with a fluorescent reporter.

Implications of probiotic butyrate delivery on cellular health and microbial community makeup in higher order model systems, such as nematodes, mice, and intestinal stem cells will also be discussed.