Characterisation and Engineering of Probiotic Saccharomyces Boulardii Promoters for Robust Therapeutic Production In Vivo.

Robust expression of therapeutics from advanced microbial therapeutics is dependent on understanding the expression profiles of relevant promoters in the gastrointestinal (GI) tract. Saccharomyces boulardii is a probiotic yeast that has been used to produce therapeutic molecules and proteins in the GI tract. While promoters of S. boulardii have been characterised under standard laboratory conditions, their activity in vivo is not known. In this study we characterise a selection of relevant promoters in vitro under gut-like conditions (including microaerobic and anaerobic conditions, and alternative carbon sources), to identify candidate promoters for further optimization. Next, promising promoters will be engineered to generate a library of robust synthetic promoters with standard expression profiles. Finally, the engineered promoters will be validated in vivo with the production of a therapeutic molecule. The study will provide researchers working with S. boulardii a comprehensive dataset on the expression profiles of commonly used native promoters, as well as providing a library of engineered promoters, validated in vivo.