CAREER: Enhancing probiotic yeast colonization for stable in situ biomanufacturing

Treating gut disease is difficult because the body digests many therapies before they reach their target. Probiotic yeast can produce many therapeutics for the gut, but this yeast does not live for a long time in the body. To solve this problem, this Faculty Early Career Development Program (CAREER) project will explore strategies to improve the ability of genetically engineered probiotics to reside in the gut. Yeast will be engineered to attach to and eat the slimy, sugar-rich mucus that line the intestines. New courses will be developed to train students in skills for microbial engineering. High school students will have the opportunity to evolve probiotics for faster growth and learn about evolution and genetics while doing so. Undergraduates will learn how to bioprospect for new genes via a new lab course developed in partnership with the NCSU Biotechnology Program (BIT). Taken together, this work will advance the ability to deliver medicines to the gut and will enhance the education of high school and undergraduate students in North Carolina. S. boulardii (Sb) is a widely available probiotic with generally-regarded-as-safe status. It is unique in that it is the only probiotic yeast (or even eukaryote), and so brings with it a unique set of advantages for in situ biomanufacturing. Both its high secretion rate and sensing ability have been used to generate promising live therapeutics. However, prior reports have indicated that Sb does not colonize the human or rat intestine for longer than one week. There are two nonexclusive strategies that commensal microbes use to colonize the gut. One is to adhere to intestinal walls, and a second strategy is to utilize gut nutrients. This work will explore both strategies for enhancement of Sb colonization, testing the hypothesis that increasing Sb’s adherence to mucus, as well as its ability to metabolize mucus glycans, would improve its residence time. Beyond these research objectives, the strong signatures of adaptive evolution observed in the gut for Sb and other probiotics have also inspired the development of an outreach module for local high schools, as well as an undergraduate laboratory course harnessing horizontal gene transfer for biotech applications. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.