| 1. |
- Chen, Yun, 1978, et al.
(författare)
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Coupled incremental precursor and co-factor supply improves 3-hydroxypropionic acid production in Saccharomyces cerevisiae
- 2014
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Ingår i: Metabolic Engineering. - : Elsevier BV. - 1096-7176 .- 1096-7184. ; 22, s. 104-109
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Tidskriftsartikel (refereegranskat)abstract
- 3-Hydroxypropionic acid (3-HP) is an attractive platform chemical, which can be used to produce a variety of commodity chemicals, such as acrylic acid and acrylamide. For enabling a sustainable alternative to petrochemicals as the feedstock for these commercially important chemicals, fermentative production of 3-HP is widely investigated and is centered on bacterial systems in most cases. However, bacteria present certain drawbacks for large-scale organic acid production. In this study, we have evaluated the production of 3-HP in the budding yeast Saccharomyces cerevisiae through a route from malonyl-CoA, because this allows performing the fermentation at low pH thus making the overall process cheaper. We have further engineered the host strain by increasing availability of the precursor malonyl-CoA and by coupling the production with increased NADPH supply we were able to substantially improve 3-HP production by five-fold, up to a final titer of 463 mg l(-1). Our work thus led to a demonstration of 3-HP production in yeast via the malonyl-CoA pathway, and this opens for the use of yeast as a cell factory for production of bio-based 3-HP and derived acrylates in the future. (C) 2014 International Metabolic Engineering Society.
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| 2. |
- Kildegaard, K. R., et al.
(författare)
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Engineering and systems-level analysis of Saccharomyces cerevisiae for production of 3-hydroxypropionic acid via malonyl-CoA reductase-dependent pathway
- 2016
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Ingår i: Microbial Cell Factories. - : Springer Science and Business Media LLC. - 1475-2859. ; 15:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: In the future, oil-and gas-derived polymers may be replaced with bio-based polymers, produced from renewable feedstocks using engineered cell factories. Acrylic acid and acrylic esters with an estimated world annual production of approximately 6 million tons by 2017 can be derived from 3-hydroxypropionic acid (3HP), which can be produced by microbial fermentation. For an economically viable process 3HP must be produced at high titer, rate and yield and preferably at low pH to minimize downstream processing costs. Results: Here we describe the metabolic engineering of baker's yeast Saccharomyces cerevisiae for biosynthesis of 3HP via a malonyl-CoA reductase (MCR)-dependent pathway. Integration of multiple copies of MCR from Chloroflexus aurantiacus and of phosphorylation-deficient acetyl-CoA carboxylase ACC1 genes into the genome of yeast increased 3HP titer fivefold in comparison with single integration. Furthermore we optimized the supply of acetyl-CoA by overexpressing native pyruvate decarboxylase PDC1, aldehyde dehydrogenase ALD6, and acetyl-CoA synthase from Salmonella enterica SEacsL641P. Finally we engineered the cofactor specificity of the glyceraldehyde-3-phosphate dehydrogenase to increase the intracellular production of NADPH at the expense of NADH and thus improve 3HP production and reduce formation of glycerol as by-product. The final strain produced 9.8 +/- 0.4 g L-1 3HP with a yield of 13 % C-mol C-mol(-1) glucose after 100 h in carbon-limited fed-batch cultivation at pH 5. The 3HP-producing strain was characterized by C-13 metabolic flux analysis and by transcriptome analysis, which revealed some unexpected consequences of the undertaken metabolic engineering strategy, and based on this data, future metabolic engineering directions are proposed. Conclusions: In this study, S. cerevisiae was engineered for high-level production of 3HP by increasing the copy numbers of biosynthetic genes and improving flux towards precursors and redox cofactors. This strain represents a good platform for further optimization of 3HP production and hence an important step towards potential commercial bio-based production of 3HP.
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| 3. |
- Kim, Il-Kwon, 1969, et al.
(författare)
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A systems-level approach for metabolic engineering of yeast cell factories
- 2012
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Ingår i: FEMS Yeast Research. - : Oxford University Press (OUP). - 1567-1356 .- 1567-1364. ; 12:2, s. 228-248
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Forskningsöversikt (refereegranskat)abstract
- The generation of novel yeast cell factories for production of high-value industrial biotechnological products relies on three metabolic engineering principles: design, construction, and analysis. In the last two decades, strong efforts have been put on developing faster and more efficient strategies and/or technologies for each one of these principles. For design and construction, three major strategies are described in this review: (1) rational metabolic engineering; (2) inverse metabolic engineering; and (3) evolutionary strategies. Independent of the selected strategy, the process of designing yeast strains involves five decision points: (1) choice of product, (2) choice of chassis, (3) identification of target genes, (4) regulating the expression level of target genes, and (5) network balancing of the target genes. At the construction level, several molecular biology tools have been developed through the concept of synthetic biology and applied for the generation of novel, engineered yeast strains. For comprehensive and quantitative analysis of constructed strains, systems biology tools are commonly used and using a multi-omics approach. Key information about the biological system can be revealed, for example, identification of genetic regulatory mechanisms and competitive pathways, thereby assisting the in silico design of metabolic engineering strategies for improving strain performance. Examples on how systems and synthetic biology brought yeast metabolic engineering closer to industrial biotechnology are described in this review, and these examples should demonstrate the potential of a systems-level approach for fast and efficient generation of yeast cell factories.
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| 4. |
- Lopez, J., et al.
(författare)
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Production of beta-ionone by combined expression of carotenogenic and plant CCD1 genes in Saccharomyces cerevisiae
- 2015
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Ingår i: Microbial Cell Factories. - : Springer Science and Business Media LLC. - 1475-2859. ; 14:1, s. Art. no. 84-
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Tidskriftsartikel (refereegranskat)abstract
- Background: Apocarotenoids, like the C13-norisoprenoids, are natural compounds that contribute to the flavor and/or aroma of flowers and foods. They are produced in aromatic plants-like raspberries and roses-by the enzymatic cleavage of carotenes. Due to their pleasant aroma and flavour, apocarotenoids have high commercial value for the cosmetic and food industry, but currently their production is mainly assured by chemical synthesis. In the present study, a Saccharomyces cerevisiae strain that synthesizes the apocarotenoid beta-ionone was constructed by combining integrative vectors and high copy number episomal vectors, in an engineered strain that accumulates FPP. Results: Integration of an extra copy of the geranylgeranyl diphosphate synthase gene (BTS1), together with the carotenogenic genes crtYB and crtI from the ascomycete Xanthophyllomyces dendrorhous, resulted in carotenoid producing cells. The additional integration of the carotenoid cleavage dioxygenase gene from the plant Petunia hybrida (PhCCD1) let to the production of low amounts of beta-ionone (0.073 +/- 0.01 mg/g DCW) and changed the color of the strain from orange to yellow. The expression of the crtYB gene from a high copy number plasmid in this former strain increased beta-ionone concentration fivefold (0.34 +/- 0.06 mg/g DCW). Additionally, the episomal expression of crtYB together with the PhCCD1 gene in the same vector resulted in a final 8.5-fold increase of beta-ionone concentration (0.63 +/- 0.02 mg/g DCW). Batch fermentations with this strain resulted in a final specific concentration of 1 mg/g DCW at 50 h, which represents a 15-fold increase. Conclusions: An efficient beta-ionone producing yeast platform was constructed by combining integrative and episomal constructs. By combined expression of the genes BTS1, the carotenogenic crtYB, crtI genes and the plant PhCCD1 gene-the highest beta-ionone concentration reported to date by a cell factory was achieved. This microbial cell factory represents a starting point for flavor production by a sustainable and efficient process that could replace current methods.
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| 5. |
- Roldao, Antonio, 1979, et al.
(författare)
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Bridging omics technologies with synthetic biology in yeast industrial biotechnology
- 2012
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Ingår i: Systems Metabolic Engineering. - Dordrecht : Springer Netherlands. ; 9789400745346, s. 271-327
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Metabolic engineering, defined as the practice of manipulating cells' genetic and regulatory processes for improving cellular performance, has been recently integrating systems and synthetic biology with other technologies, e.g. molecular biology, physiology, biochemistry, analysis science, bioinformatics and biochemical engineering. The aim is to surmount cells' performance-related limitations, e.g. metabolic limitation of cellular processes, network rigidity and global regulation, in a comprehensive, rational and high-throughput manner. Using this multi-level/integrated approach, the (re)design and (re)construction of microbial systems for the development of novel products with significant impact on current global problems, e.g. depletion of energy resources and global warming, is becoming a reality. In the last two decades, technological platforms for systems biology, e.g. genomics, transcriptomics, proteomics, metabolomics and fluxomics, and synthetic biology approaches, e.g. synthetic biological parts, devices and systems, have been implemented and efficiently used as tools for metabolic engineering of high-value bioproducts. One successful story on how metabolic engineering has been used to enhance the synthesis of microbial-based molecules is the production of biofuels. In this review, synthetic and systems biology technologies for yeast metabolic engineering will be described in detail. In addition, two case studies related with biofuel production (ethanol and 1-butanol) in yeast S. cerevisiae will be presented.
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