Genetic engineering of Yarrowia lipolytica for the sustainable production of food oils

Abstract: The human population and its demand for food oils is constantly growing. However, increasing food oil production currently requires the deforestation of mostly tropical rainforests to allow the plantation of oil crops. Because of the massive risks caused by climate change and increased awareness for biodiversity, we need to find alternative ways to produce food oils. Microbial cell factories can be such an alternative. A very promising host organism is the oleaginous yeast Yarrowia lipolytica . One of Y. lipolytica's characteristics is its ability to accumulate high amounts of lipids, making it especially interesting to produce fatty acid-derived products, such as triacylglycerides (TAGs). To establish Y. lipolytica as a food oil production platform, we first abolished its ability to form filaments by deletion MHY1. As a proof of concept, we aimed to mimic cocoa butter as a high value product. We exchanged the Δ9 desaturase OLE1 with homologs from other species and altered the expression level of both Δ9 and Δ12 desaturase to mimic the fatty acid composition of cocoa butter. To increase the sustainability, we engineered our strain to consume xylose as an alternative carbon source and investigated the effect of different inhibitors commonly found in hydrolysates on Y. lipolytica . Finally, we identified urea as an alternative nitrogen source by running chemostat cultivations and performing RNA sequencing. Overall, this thesis achieved different relevant aspects to develop Y. lipolytica as a microbial cell factory for food oils.