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2 results on '"Lindahl, Lina"'

1. Membrane engineering of S. cerevisiae targeting sphingolipid metabolism.

Author

Lindahl L, Santos AX, Olsson H, Olsson L, and Bettiga M

Subjects
Acetyltransferases genetics, Acetyltransferases metabolism, Hexosyltransferases genetics, Hexosyltransferases metabolism, Saccharomyces cerevisiae metabolism, Saccharomyces cerevisiae Proteins genetics, Saccharomyces cerevisiae Proteins metabolism, Cell Membrane metabolism, Saccharomyces cerevisiae genetics, Sphingolipids metabolism
Abstract

The sustainable production of fuels and chemicals using microbial cell factories is now well established. However, many microbial production processes are still limited in scale due to inhibition from compounds that are present in the feedstock or are produced during fermentation. Some of these inhibitors interfere with cellular membranes and change the physicochemical properties of the membranes. Another group of molecules is dependent on their permeation rate through the membrane for their inhibition. We have investigated the use of membrane engineering to counteract the negative effects of inhibitors on the microorganism with focus on modulating the abundance of complex sphingolipids in the cell membrane of Saccharomyces cerevisiae. Overexpression of ELO3, involved in fatty acid elongation, and AUR1, which catalyses the formation of complex sphingolipids, had no effect on the membrane lipid profile or on cellular physiology. Deletion of the genes ORM1 and ORM2, encoding negative regulators of sphingolipid biosynthesis, decreased cell viability and considerably reduced phosphatidylinositol and complex sphingolipids. Additionally, combining ELO3 and AUR1 overexpression with orm1/2Δ improved cell viability and increased fatty acyl chain length compared with only orm1/2Δ. These findings can be used to further study the sphingolipid metabolism, as well as giving guidance in membrane engineering., Competing Interests: The authors declare no competing financial interests.

Published
2017
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2. Sphingolipids contribute to acetic acid resistance in Zygosaccharomyces bailii

Author

Lindahl, Lina, Genheden, Samuel, Eriksson, Leif A., Olsson, Lisbeth, and Bettiga, Maurizio

Subjects
Sphingolipids, myriocin, Antifungal Agents, Cell Membrane, Biofuels and Environmental Biotechnology, Zygosaccharomyces, Articles, molecular dynamics simulations, Molecular Dynamics Simulation, Lignin, Article, Permeability, Culture Media, Fatty Acids, Monounsaturated, lignocellulose, membrane permeability, inhibitors, acetic acid tolerance, Acetic Acid
Abstract

Lignocellulosic raw material plays a crucial role in the development of sustainable processes for the production of fuels and chemicals. Weak acids such as acetic acid and formic acid are troublesome inhibitors restricting efficient microbial conversion of the biomass to desired products. To improve our understanding of weak acid inhibition and to identify engineering strategies to reduce acetic acid toxicity, the highly acetic‐acid‐tolerant yeast Zygosaccharomyces bailii was studied. The impact of acetic acid membrane permeability on acetic acid tolerance in Z. bailii was investigated with particular focus on how the previously demonstrated high sphingolipid content in the plasma membrane influences acetic acid tolerance and membrane permeability. Through molecular dynamics simulations, we concluded that membranes with a high content of sphingolipids are thicker and more dense, increasing the free energy barrier for the permeation of acetic acid through the membrane. Z. bailii cultured with the drug myriocin, known to decrease cellular sphingo­lipid levels, exhibited significant growth inhibition in the presence of acetic acid, while growth in medium without acetic acid was unaffected by the myriocin addition. Furthermore, following an acetic acid pulse, the intracellular pH decreased more in myriocin‐treated cells than in control cells. This indicates a higher inflow rate of acetic acid and confirms that the reduction in growth of cells cultured with myriocin in the medium with acetic acid was due to an increase in membrane permeability, thereby demonstrating the importance of a high fraction of sphingolipids in the membrane of Z. bailii to facilitate acetic acid resistance; a property potentially transferable to desired production organisms suffering from weak acid stress. Biotechnol. Bioeng. 2016;113: 744–753. © 2015 The Authors. Biotechnology and Bioengineering Published by Wiley Periodicals, Inc.

Published
2015

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