| 44511. |
- Konzock, Oliver, 1991, et al.
(författare)
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Altering the fatty acid profile of Yarrowia lipolytica to mimic cocoa butter by genetic engineering of desaturases
- 2022
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Ingår i: Microbial Cell Factories. - : Springer Science and Business Media LLC. - 1475-2859. ; 21:1, s. 25-
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Demand for Cocoa butter is steadily increasing, but the supply of cocoa beans is naturally limited and under threat from global warming. One route to meeting the future demand for cocoa butter equivalent (CBE) could be to utilize microbial cell factories such as the oleaginous yeast Yarrowia lipolytica. RESULTS: The main goal was to achieve triacyl-glycerol (TAG) storage lipids in Y. lipolytica mimicking cocoa butter. This was accomplished by replacing the native Δ9 fatty acid desaturase (Ole1p) with homologs from other species and changing the expression of both Ole1p and the Δ12 fatty acid desaturase (Fad2p). We thereby abolished the palmitoleic acid and reduced the linoleic acid content in TAG, while the oleic acid content was reduced to approximately 40 percent of the total fatty acids. The proportion of fatty acids in TAG changed dramatically over time during growth, and the fatty acid composition of TAG, free fatty acids and phospholipids was found to be very different. CONCLUSIONS: We show that the fatty acid profile in the TAG of Y. lipolytica can be altered to mimic cocoa butter. We also demonstrate that a wide range of fatty acid profiles can be achieved while maintaining good growth and high lipid accumulation, which, together with the ability of Y. lipolytica to utilize a wide variety of carbon sources, opens up the path toward sustainable production of CBE and other food oils.
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| 44512. |
- Konzock, Oliver, 1991, et al.
(författare)
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Cinnamic acid and p-coumaric acid are metabolized to 4-hydroxybenzoic acid by Yarrowia lipolytica
- 2023
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Ingår i: AMB Express. - 2191-0855. ; 13:1
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Tidskriftsartikel (refereegranskat)abstract
- Yarrowia lipolytica has been explored as a potential production host for flavonoid synthesis due to its high tolerance to aromatic acids and ability to supply malonyl-CoA. However, little is known about its ability to consume the precursors cinnamic and p-coumaric acid. In this study, we demonstrate that Y. lipolytica can consume these precursors through multiple pathways that are partially dependent on the cultivation medium. By monitoring the aromatic acid concentrations over time, we found that cinnamic acid is converted to p-coumaric acid. We identified potential proteins with a trans-cinnamate 4-monooxygenase activity in Y. lipolytica and constructed a collection of 15 knock-out strains to identify the genes responsible for the reaction. We identified YALI1_B28430g as the gene encoding for a protein that converts cinnamic acid to p-coumaric acid (designated as TCM1). By comparing different media compositions we found that complex media components (casamino acids and yeast extract) induce this pathway. Additionally, we discover the conversion of p-coumaric acid to 4-hydroxybenzoic acid. Our findings provide new insight into the metabolic capabilities of Y. lipolytica and hold great potential for the future development of improved strains for flavonoid production.
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| 44513. |
- Konzock, Oliver, 1991, et al.
(författare)
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Deletion of MHY1 abolishes hyphae formation in Yarrowia lipolytica without negative effects on stress tolerance
- 2020
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203 .- 1932-6203. ; 15:4
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Tidskriftsartikel (refereegranskat)abstract
- There is a need for development of sustainable production processes for production of fats/oils and lipid derived chemicals. The dimorphic oleaginous yeast Yarrowia lipolytica is a promising organism for conversion of biomass hydrolysate to lipids, but in many such processes hyphae formation will be problematic. We have therefore constructed and compared the performance of strains carrying deletions in several published gene targets suggested to abolish hyphae formation (MHY1, HOY1 and CLA4). The MHY1-deletion was the only of the tested strains which did not exhibit hyphae formation under any of the conditions tested. The MHY1-deletion also had a weak positive effect on lipid accumulation without affecting the total fatty acid composition, irrespective of the nitrogen source used. MHY1 has been suggested to constitute a functional homolog of the stress responsive transcription factors MSN2/4 in Saccharomyces cerevisiae, the deletion of which are highly stress sensitive. However, the deletion of MHY1 displayed only minor difference on survival of a range of acute or long term stress and starvation conditions. We conclude that the deletion of MHY1 in Y.lipolytica is a reliable way of abolishing hyphae formation with few detectable negative side effects regarding growth, stress tolerance and lipid accumulation and composition.
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| 44514. |
- Konzock, Oliver, 1991
(författare)
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Genetic engineering of Yarrowia lipolytica for the sustainable production of food oils
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)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.
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| 44515. |
- Konzock, Oliver, 1991, et al.
(författare)
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Tolerance of Yarrowia lipolytica to inhibitors commonly found in lignocellulosic hydrolysates
- 2021
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Ingår i: BMC Microbiology. - : Springer Science and Business Media LLC. - 1471-2180. ; 21:1
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Tidskriftsartikel (refereegranskat)abstract
- Background Lignocellulosic material is a suitable renewable carbon and energy source for microbial cell factories, such as Yarrowia lipolytica. To be accessible for microorganisms, the constituent sugars need to be released in a hydrolysis step, which as a side effect leads to the formation of various inhibitory compounds. However, the effects of these inhibitory compounds on the growth of Y. lipolytica have not been thoroughly investigated. Results Here we show the individual and combined effect of six inhibitors from three major inhibitor groups on the growth of Y. lipolytica. We engineered a xylose consuming strain by overexpressing the three native genes XR, XDH, and XK and found that the inhibitor tolerance of Y. lipolytica is similar in glucose and in xylose. Aromatic compounds could be tolerated at high concentrations, while furfural linearly increased the lag phase of the cultivation, and hydroxymethylfurfural only inhibited growth partially. The furfural induced increase in lag phase can be overcome by an increased volume of inoculum. Formic acid only affected growth at concentrations above 25 mM. In a synthetic hydrolysate, formic acid, furfural, and coniferyl aldehyde were identified as the major growth inhibitors. Conclusion We showed the individual and combined effect of inhibitors found in hydrolysate on the growth of Y. lipolytica. Our study improves understanding of the growth limiting inhibitors found in hydrolysate and enables a more targeted engineering approach to increase the inhibitor tolerance of Y. lipolytica. This will help to improve the usage of Y. lipolytica as a sustainable microbial cell factory.
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| 44516. |
- Konzock, Oliver, 1991, et al.
(författare)
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TRYing to evaluate production costs in microbial biotechnology
- 2024
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Ingår i: Trends in Biotechnology. - 0167-7799 .- 1879-3096. ; In Press
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Forskningsöversikt (refereegranskat)abstract
- Microbial fermentations offer the opportunity to produce a wide range of chemicals in a sustainable fashion, but it is important to carefully evaluate the production costs. This can be done on the basis of evaluation of the titer, rate, and yield (TRY) of the fermentation process. Here we describe how the three TRY metrics impact the technoeconomics of a microbial fermentation process, and we illustrate the use of these for evaluation of different processes in the production of two commodity chemicals, 1,3-propanediol (PDO) and ethanol, as well as for the fine chemical penicillin. On the basis of our discussions, we provide some recommendations on how the TRY metrics should be reported when new processes are described.
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| 44517. |
- Konzock, Oliver, 1991, et al.
(författare)
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Urea is a drop-in nitrogen source alternative to ammonium sulphate in Yarrowia lipolytica
- 2022
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Ingår i: iScience. - : Elsevier BV. - 2589-0042. ; 25:12
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Tidskriftsartikel (refereegranskat)abstract
- Media components, including the nitrogen source, are significant cost factors in cultivation processes. The nitrogen source also influences cell behavior and production performance. Ammonium sulfate is a widely used nitrogen source for microorganisms’ cultivation. Urea is a sustainable and cheap alternative nitrogen source. We investigated the influence of urea as a nitrogen source compared to ammonium sulfate by cultivating phenotypically different Yarrowia lipolytica strains in chemostats under carbon or nitrogen limitation. We found no significant coherent changes in growth and lipid production. RNA sequencing revealed no significant concerted changes in the transcriptome. The genes involved in urea uptake and degradation are not upregulated on a transcriptional level. Our findings support urea usage, indicating that previous metabolic engineering efforts where ammonium sulfate was used are likely translatable to the usage of urea and can ease the way for urea as a cheap and sustainable nitrogen source in more applications.
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| 44518. |
- Koo, J. H., et al.
(författare)
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Global climatology based on the ACE-FTS version 3.5 dataset: Addition of mesospheric levels and carbon-containing species in the UTLS
- 2017
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Ingår i: Journal of Quantitative Spectroscopy and Radiative Transfer. - : Elsevier BV. - 0022-4073. ; 186, s. 52-62
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we present a new climatology based on, the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) version 3.5 data set from February 2004 to February 2013. This extends the ACE-FTS climatology to include profile information in the mesosphere and carbon-containing species in the upper troposphere and lower stratosphere. Climatologies of 21 species, based on nine years of observations, are calculated, providing the most comprehensive and self-consistent climatology available from limb-viewing satellite measurements. Pressure levels from the upper troposphere to the mesosphere and lower thermosphere are included with similar to 3 to 4 km vertical resolution up to 10(-4) hPa (similar to 105 km). Volume mixing ratio values are filtered prior to the climatology estimation using the ACE-FTS data quality recommendations. The multi-year mean climatology contains zonal mean profiles for monthly and three-monthly (DJF, MAM, JJA, and SON) periods. These are provided with 5-degree spacing in either latitude or equivalent latitude. Also, the local daytime and nighttime distributions are provided separately for nitrogen-containing species, enabling diurnal differences to be investigated. Based on this climatology, examples of typical spatiotemporal patterns for trace gases in the mesosphere and for carbon-containing gases in the upper troposphere and lower stratosphere are discussed. (C) 2016 Elsevier Ltd. All rights reserved.
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| 44519. |
- Koohestani, M., et al.
(författare)
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Diversity Gain Influenced by Polarization and Spatial Diversity Techniques in Ultrawideband
- 2015
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Ingår i: IEEE Access. - : Institute of Electrical and Electronics Engineers (IEEE). - 2169-3536 .- 2169-3536. ; 3, s. 281-286
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents an experimental investigation of diversity gain influenced by polarization and spatial diversity techniques in ultrawideband (UWB) radio technology. To this aim, two different coplanar-fed UWB diversity antennas having the same size and employing identical monopoles were taken and both effective and apparent diversity gain were measured in a reverberation chamber. To extract the diversity gain, three commonly used approaches to combine diversity (i.e., selection, equal gain, and maximal ratio) have been considered. Results showed that >1 dB (similar to 26%) improvement in diversity gain is obtained over most of the considered band for polarization diversity case as compared with spatial case, showing the usefulness of polarization diversity for future UWB diversity applications.
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| 44520. |
- Koohestani, M., et al.
(författare)
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Frequency Selective Surfaces for Electromagnetic Shielding of Pocket-Sized Transceivers
- 2020
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Ingår i: IEEE Transactions on Electromagnetic Compatibility. - 0018-9375 .- 1558-187X. ; 62:6, s. 2785-2792
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Tidskriftsartikel (refereegranskat)abstract
- This article presents a comprehensive study of the use of small-sized frequency selective surfaces (FSS) to selectively shield pocket-sized devices against EM disturbances. A typical use case is to protect a 2.4-GHz transceiver (e.g. WiFi/Bluetooth) against ISM/GSM disturbances (around 868/915 MHz), using an 8.2 – 4.1 cm FSS structure. A detailed comparison is drawn between results in real and emulated far-fields for different FSS-to-antenna distances (5 and 25 mm), which is further confirmed by emission measurements employing an open transverse electromagnetic cell. Results demonstrate, in line with full-wave simulations including calculated Poynting integrals, that such a FSS can effectively reduce power by about 5 dB in the stopband, while providing no attenuation in the passband and is small enough for an easy integration. Moreover, it is shown that the farther the FSS from the antenna, the closer the results to a no-FSS scenario. This provides an insight to reconsider FSSs for the shielding of mobile and/or smart devices.
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