Genetic engineering of Yarrowia lipolytica for the sustainable production of food oils
Doctoral thesis, 2022
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.
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.
triacyclglycerols
RNA-seq
tolerance
cocoa butter
hydrolysate
yeast
desaturase
filamentation
Chalmers Johanneberg Campus conference room 10’an, Chemistry building floor
Opponent: Rodrigo Ledesma-Amaro, Imperial College London, UK
Author
Oliver Konzock
Chalmers, Biology and Biological Engineering, Systems and Synthetic Biology
Deletion of MHY1 abolishes hyphae formation in Yarrowia lipolytica without negative effects on stress tolerance
PLoS ONE,;Vol. 15(2020)
Journal article
Altering the fatty acid profile of Yarrowia lipolytica to mimic cocoa butter by genetic engineering of desaturases
Microbial Cell Factories,;Vol. 21(2022)p. 25-
Journal article
Tolerance of Yarrowia lipolytica to inhibitors commonly found in lignocellulosic hydrolysates
BMC Microbiology,;Vol. 21(2021)
Journal article
Urea is a drop-in nitrogen source alternative to ammonium sulphate in Yarrowia lipolytica
iScience,;Vol. 25(2022)
Journal article
Producing food oils from wood in yeast
The human population is constantly growing. And so is its demand for food oils. However, an increase in 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 of biodiversity, we need to find alternative ways to produce food oils.
Help could come from the tiniest living beings on earth – microorganisms. Microorganisms have been isolated and cultivated to produce a variety of products. A very promising host organism is the yeast Yarrowia lipolytica. One of its characteristics is the ability to accumulate high amounts of fat, making it especially interesting to produce fatty acid-derived products, such as food oils.
This thesis explores four different approaches to advance Y. lipolytica as a platform organism for sustainable food oil production. By genetic engineering, we abolished filamentation, an unfavourable behaviour in industrial applications. We then altered the fatty acid profile of Y. lipolytica by tinkering with proteins called desaturases to mimic a high-value food oil – cocoa butter. To increase the sustainability of the production, we further explored lignocellulosic hydrolysates (e.g. from wood) as an alternative to feed our yeast. By overexpressing native genes, Y. lipolytica utilized xylose as a carbon source. Additionally, we documented the tolerance of our yeast to inhibitors commonly found in hydrolysates. Finally, we compared urea to ammonium sulphate as an alternative nitrogen source using transcriptomic analysis.
The human population is constantly growing. And so is its demand for food oils. However, an increase in 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 of biodiversity, we need to find alternative ways to produce food oils.
Help could come from the tiniest living beings on earth – microorganisms. Microorganisms have been isolated and cultivated to produce a variety of products. A very promising host organism is the yeast Yarrowia lipolytica. One of its characteristics is the ability to accumulate high amounts of fat, making it especially interesting to produce fatty acid-derived products, such as food oils.
This thesis explores four different approaches to advance Y. lipolytica as a platform organism for sustainable food oil production. By genetic engineering, we abolished filamentation, an unfavourable behaviour in industrial applications. We then altered the fatty acid profile of Y. lipolytica by tinkering with proteins called desaturases to mimic a high-value food oil – cocoa butter. To increase the sustainability of the production, we further explored lignocellulosic hydrolysates (e.g. from wood) as an alternative to feed our yeast. By overexpressing native genes, Y. lipolytica utilized xylose as a carbon source. Additionally, we documented the tolerance of our yeast to inhibitors commonly found in hydrolysates. Finally, we compared urea to ammonium sulphate as an alternative nitrogen source using transcriptomic analysis.
Fat from wood: Optimizing the yeast Yarrowia lipolytica for defined composition food oil production from lignocellulosic hydrolysate
Formas (2017-01281), 2018-01-01 -- 2021-12-31.
Subject Categories
Food Science
Biological Sciences
Other Environmental Engineering
Microbiology
Bioinformatics and Systems Biology
ISBN
978-91-7905-637-7
Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 5103
Publisher
Chalmers
Chalmers Johanneberg Campus conference room 10’an, Chemistry building floor
Opponent: Rodrigo Ledesma-Amaro, Imperial College London, UK