Study of probiotic yeast behaviour in the gut ^{CEFR B1}

Nathan Crook, an associate professor at North Carolina State University, and his team studied how the probiotic yeast Saccharomyces boulardii (Sb) behaves in the gut to inform new ways to deliver therapeutic molecules. They chose Sb because it is the only yeast species used as a probiotic, yet its biochemical activity in the gut was not well understood.

For the experiments the researchers introduced an off-the-shelf, non‑modified Sb strain into germ-free mice and collected fecal and intestinal samples. They combined established sampling and analytical techniques in a novel way to measure the RNA produced by the yeast as it passed through the animals. With no other microbes present, the yeast RNA was easier to identify.

The team found genes that are more likely to be active in the gut than in other environments. Some of these active regions include promoter sections that can act as on-switches. Targeting those promoters could tell engineered yeast when to start making therapeutic molecules, improving drug delivery. Genes linked to potentially pathogenic behaviour were not activated, which supports Sb's safety and justifies further engineering. Gene activity also suggested the gut is not nutrient-rich for Sb; the yeast used more lipids than carbohydrates, so the researchers suggest modifying Sb to use complex carbohydrates to fuel production. The paper appears in BMC Genomics and the authors have filed patent applications and invention disclosures. Support came from the National Science Foundation, the Novo Nordisk Foundation, and the National Institutes of Health.