Engineering Lipid Metabolism for Production of Oleochemicals in Saccharomyces cerevisiae
Doktorsavhandling, 2018

Oleochemicals are chemicals usually derived from plant oils or animal fat. Large use of plant oil derivatives as replacements for petroleum-derived chemicals brings sustainability issues from extensive cultivation of oil plants in restricted regions. This project studied and developed the baker’s yeast Saccharomyces cerevisiae as a platform for sustainable production of oleochemical precursors. The first part of this work studied the dynamics of free fatty acids (FFAs) production. First, an alternative fatty acid synthesis system based on the reverse β-oxidation pathway was evaluated for its in vivo function but concluding that it was not an efficient route for fatty acid synthesis. The subsequent studies were based on high level production of FFA and secretion to the extracellular medium through removal of acyl-CoA synthase activity by deleting the FAA1-4 genes. This phenotype was coupled to a pathway that converts FFA to fatty alcohols, which allowed the observation that while FFA are more efficiently converted to fatty alcohols during growth on glucose, the production of FFA is highly increased during growth on ethanol. Fine-tuning of FAA1 expression resulted in improved production of fatty alcohols without FFA secretion in this strain. Following up, the pathways leading to FFA formation in a Δfaa1 Δfaa4 background were studied through construction of a strain with a constrained lipid metabolism network. It was observed that upon removing storage lipid formation, phospholipid synthesis had a strong correlation with FFA production and FFA formation was mostly derived from phospholipid hydrolysis. On the second part of this work, S. cerevisiae was engineered for the highest TAG production levels reported so far. This relied on overexpressing genes involved in malonyl-CoA supply and TAG synthesis from acyl-CoA, and removing genes involved in TAG hydrolysis, β-oxidation and glycerol-3-phosphate usage. On a second approach, TAG accumulation properties were further improved in these strains through enhancing lipid droplet assembly processes. This was achieved through expression of perilipins and FIT proteins and through stimulation of ER stress mechanisms. In conclusion, lipid metabolism is an important part of cell homeostasis and engineering this system requires overcoming its tight regulation networks and mastering the processes involved in the physical structural organization of the system. Here this was highlighted using both knowledge-driven studies and engineering approaches, leading to important advancements in the field.

lipid metabolism


<i>Saccharomyces cerevisiae</i>

lipid homeostasis

Lecture Hall KB
Opponent: Nils J. Færgeman, University of Southern Denmark, SDU, Denmark


Paulo Teixeira

Chalmers, Biologi och bioteknik, Systembiologi

Dynamic regulation of fatty acid pools for improved production of fatty alcohols in Saccharomyces cerevisiae

Microbial Cell Factories,; Vol. 16(2017)p. 45-

Artikel i vetenskaplig tidskrift

Teixeira PG, Siewers V, Nielsen J. Quantitative in vivo evaluation of the reversed β-oxidation pathway for fatty acid production in Saccharomyces cerevisiae.

Ferreira R*, Teixeira PG*, Siewers V, Nielsen J. Redirection of lipid flux towards phospholipids in yeast increases fatty acid turnover and secretion.

Ferreira R, Teixeira PG, Gossing M, David F, Siewers V, Nielsen J. Metabolic engineering of Saccharomyces cerevisiae for overproduction of triacylglycerols.

Teixeira PG, David F, Siewers V, Nielsen J. Engineering lipid droplet structural features for increased triacylglycerol accumulation in Saccharomyces cerevisiae.

For many years, our society and industry has been dependent on fossil sources for energy (fuels) and materials (chemicals). While the dependency on fossil fuels for energy is still a global concern, a large portion of petroleum-derived chemicals (petrochemicals) has been replaced in the last decades by plant-oil-derived chemicals (oleochemicals). While plant-derived chemicals is a renewable solution, extensive cultivation of oil plants raises a number of sustainability problems including destruction of habitats, deforestation, competition with arable land and highly region-dependent industries. This thesis explores the use of the common baker’s yeast Saccharomyces cerevisiae to produce oleochemicals from sustainable plant sources. Natively, this yeast uses sugar to produce ethanol. Through genetic engineering, yeast can be modified to use these same sugars and produce lipid species that are used in the oleochemical industry. For this, we need to rewire its lipid metabolism, which requires a deep understanding of the genetic and molecular interactions that compose this system. This work was developed in two simultaneous directions. First, existing knowledge was used to engineer the lipid metabolism of yeast and increase production of oleochemicals. Secondly, the effects of such engineering targets were studied in order to better understand underlying aspects of lipid metabolism that are not completely described by the scientific community.


Hållbar utveckling

Innovation och entreprenörskap



Biokemi och molekylärbiologi

Biokatalys och enzymteknik


Chalmers infrastruktur för masspektrometri


Livsvetenskaper och teknik



Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 4367


Chalmers tekniska högskola

Lecture Hall KB

Opponent: Nils J. Færgeman, University of Southern Denmark, SDU, Denmark