Dataset Information

Evolutionary engineering improves tolerance for medium-chain alcohols in Saccharomyces cerevisiae.

ABSTRACT: Background:Yeast-based chemical production is an environmentally friendly alternative to petroleum-based production or processes that involve harsh chemicals. However, many potential alcohol biofuels, such as n-butanol, isobutanol and n-hexanol, are toxic to production organisms, lowering the efficiency and cost-effectiveness of these processes. We set out to improve the tolerance of Saccharomyces cerevisiae toward these alcohols. Results:We evolved the laboratory strain of S. cerevisiae BY4741 to be more tolerant toward n-hexanol and show that the mutations which confer tolerance occur in proteins of the translation initiation complex. We found that n-hexanol inhibits initiation of translation and evolved mutations in the ? subunit of eIF2 and the ? subunit of its guanine exchange factor eIF2B rescue this inhibition. We further demonstrate that translation initiation is affected by other alcohols such as n-pentanol and n-heptanol, and that mutations in the eIF2 and eIF2B complexes greatly improve tolerance to these medium-chain alcohols. Conclusions:We successfully generated S. cerevisiae strains that have improved tolerance toward medium-chain alcohols and have demonstrated that the causative mutations overcome inhibition of translation initiation by these alcohols.

SUBMITTER: Davis Lopez SA

PROVIDER: S-EPMC5880003 | biostudies-literature | 2018

REPOSITORIES: biostudies-literature

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Evolutionary engineering improves tolerance for medium-chain alcohols in <i>Saccharomyces cerevisiae</i>.

Davis López Stephanie A SA Griffith Douglas Andrew DA Choi Brian B Cate Jamie H D JHD Tullman-Ercek Danielle D

Biotechnology for biofuels 20180402

<h4>Background</h4>Yeast-based chemical production is an environmentally friendly alternative to petroleum-based production or processes that involve harsh chemicals. However, many potential alcohol biofuels, such as <i>n</i>-butanol, isobutanol and <i>n</i>-hexanol, are toxic to production organisms, lowering the efficiency and cost-effectiveness of these processes. We set out to improve the tolerance of <i>Saccharomyces cerevisiae</i> toward these alcohols.<h4>Results</h4>We evolved the labora ...[more]

PMID: 29619086

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Project description:Fatty acid-derived biofuels and biochemicals can be produced in microbes using β-oxidation pathway engineering. In this study, the β-oxidation pathway of Saccharomyces cerevisiae was engineered to accumulate a higher ratio of medium chain fatty acids (MCFAs) when cells were grown on fatty acid-rich feedstock. For this purpose, the haploid deletion strain Δpox1 was obtained, in which the sole acyl-CoA oxidase encoded by POX1 was deleted. Next, the POX2 gene from Yarrowia lipolytica, which encodes an acyl-CoA oxidase with a preference for long chain acyl-CoAs, was expressed in the Δpox1 strain. The resulting Δpox1 [pox2+] strain exhibited a growth defect because the β-oxidation pathway was blocked in peroxisomes. To unblock the β-oxidation pathway, the gene CROT, which encodes carnitine O-octanoyltransferase, was expressed in the Δpox1 [pox2+] strain to transport the accumulated medium chain acyl-coAs out of the peroxisomes. The obtained Δpox1 [pox2+, crot+] strain grew at a normal rate. The effect of these genetic modifications on fatty acid accumulation and profile was investigated when the strains were grown on oleic acids-containing medium. It was determined that the engineered strains Δpox1 [pox2+] and Δpox1 [pox2+, crot+] had increased fatty acid accumulation and an increased ratio of MCFAs. Compared to the wild-type (WT) strain, the total fatty acid production of the strains Δpox1 [pox2+] and Δpox1 [pox2+, crot+] were increased 29.5% and 15.6%, respectively. The intracellular level of MCFAs in Δpox1 [pox2+] and Δpox1 [pox2+, crot+] increased 2.26- and 1.87-fold compared to the WT strain, respectively. In addition, MCFAs in the culture medium increased 3.29-fold and 3.34-fold compared to the WT strain. These results suggested that fatty acids with an increased MCFAs ratio accumulate in the engineered strains with a modified β-oxidation pathway. Our approach exhibits great potential for transforming low value fatty acid-rich feedstock into high value fatty acid-derived products.

Dataset Information

Evolutionary engineering improves tolerance for medium-chain alcohols in Saccharomyces cerevisiae.

Publications

Evolutionary engineering improves tolerance for medium-chain alcohols in <i>Saccharomyces cerevisiae</i>.

Similar Datasets

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