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An engineered fatty acid synthase combined with a carboxylic acid reductase enables de novo production of 1-octanol in Saccharomyces cerevisiae
- Background: The ideal biofuel should not only be a regenerative fuel from renewable feedstocks, but should also be compatible with the existing fuel distribution infrastructure and with normal car engines. As the so-called drop-in biofuel, the fatty alcohol 1-octanol has been described as a valuable substitute for diesel and jet fuels and has already been produced fermentatively from sugars in small amounts with engineered bacteria via reduction of thioesterase-mediated premature release of octanoic acid from fatty acid synthase or via a reversal of the β-oxidation pathway. Results: The previously engineered short-chain acyl-CoA producing yeast Fas1R1834K/Fas2 fatty acid synthase variant was expressed together with carboxylic acid reductase from Mycobacterium marinum and phosphopantetheinyl transferase Sfp from Bacillus subtilis in a Saccharomyces cerevisiae Δfas1 Δfas2 Δfaa2 mutant strain. With the involvement of endogenous thioesterases, alcohol dehydrogenases, and aldehyde reductases, the synthesized octanoyl-CoA was converted to 1-octanol up to a titer of 26.0 mg L−1 in a 72-h fermentation. The additional accumulation of 90 mg L−1 octanoic acid in the medium indicated a bottleneck in 1-octanol production. When octanoic acid was supplied externally to the yeast cells, it could be efficiently converted to 1-octanol indicating that re-uptake of octanoic acid across the plasma membrane is not limiting. Additional overexpression of aldehyde reductase Ahr from Escherichia coli nearly completely prevented accumulation of octanoic acid and increased 1-octanol titers up to 49.5 mg L−1. However, in growth tests concentrations even lower than 50.0 mg L−1 turned out to be inhibitory to yeast growth. In situ extraction in a two-phase fermentation with dodecane as second phase did not improve growth, indicating that 1-octanol acts inhibitive before secretion. Furthermore, 1-octanol production was even reduced, which results from extraction of the intermediate octanoic acid to the organic phase, preventing its re-uptake. Conclusions: By providing chain length control via an engineered octanoyl-CoA producing fatty acid synthase, we were able to specifically produce 1-octanol with S. cerevisiae. Before metabolic engineering can be used to further increase product titers and yields, strategies must be developed that cope with the toxic effects of 1-octanol on the yeast cells.
Author: | Sandra Henritzi, Manuel Fischer, Martin GriningerORCiDGND, Igor-Mislav OrebORCiDGND, Eckhard BolesORCiD |
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URN: | urn:nbn:de:hebis:30:3-466075 |
DOI: | https://doi.org/10.1186/s13068-018-1149-1 |
ISSN: | 1754-6834 |
Pubmed Id: | https://pubmed.ncbi.nlm.nih.gov/29881455 |
Parent Title (English): | Biotechnology for biofuels |
Publisher: | BioMed Central |
Place of publication: | London |
Document Type: | Article |
Language: | English |
Year of Completion: | 2018 |
Date of first Publication: | 2018/06/01 |
Publishing Institution: | Universitätsbibliothek Johann Christian Senckenberg |
Release Date: | 2018/06/14 |
Tag: | 1-octanol; Biofuel; Caprylic acid; Carboxylic acid reductase; Fatty acid synthase; Fatty alcohol; Octanoic acid; Saccharomyces cerevisiae; Short-chain fatty acids; Yeast |
Volume: | 11 |
Issue: | Art. 150 |
Page Number: | 12 |
First Page: | 1 |
Last Page: | 12 |
Note: | Open Access: This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. |
HeBIS-PPN: | 433867051 |
Institutes: | Biochemie, Chemie und Pharmazie / Biochemie und Chemie |
Biowissenschaften / Biowissenschaften | |
Exzellenzcluster / Exzellenzcluster Makromolekulare Komplexe | |
Dewey Decimal Classification: | 5 Naturwissenschaften und Mathematik / 57 Biowissenschaften; Biologie / 570 Biowissenschaften; Biologie |
Sammlungen: | Universitätspublikationen |
Open-Access-Publikationsfonds: | Biowissenschaften |
Licence (German): | Creative Commons - Namensnennung 4.0 |