Dataset Information
Improving squalene production by enhancing the NADPH/NADP+ ratio, modifying the isoprenoid-feeding module and blocking the menaquinone pathway in Escherichia coli.
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ABSTRACT: Background
Squalene is currently used widely in the food, cosmetics, and medicine industries. It could also replace petroleum as a raw material for fuels. Microbial fermentation processes for squalene production have been emerging over recent years. In this study, to study the squalene-producing potential of Escherichia coli (E. coli), we employed several increasing strategies for systematic metabolic engineering. These include the expression of human truncated squalene synthase, the overexpression of rate-limiting enzymes in isoprenoid pathway, the modification of isoprenoid-feeding module and the blocking of menaquinone pathway.Results
Herein, human truncated squalene synthase was engineered in Escherichia coli to create a squalene-producing bacterial strain. To increase squalene yield, we employed several metabolic engineering strategies. A fivefold squalene titer increase was achieved by expressing rate-limiting enzymes (IDI, DXS, and FPS) involved in the isoprenoid pathway. Pyridine nucleotide transhydrogenase (UdhA) was then expressed to improve the cellular NADPH/NADP+ ratio, resulting in a 59% increase in squalene titer. The Embden-Meyerhof pathway (EMP) was replaced with the Entner-Doudoroff pathway (EDP) and pentose phosphate pathway (PPP) to feed the isoprenoid pathway, along with the overexpression of zwf and pgl genes which encode rate-limiting enzymes in the EDP and PPP, leading to a 104% squalene content increase. Based on the blocking of menaquinone pathway, a further 17.7% increase in squalene content was achieved. Squalene content reached a final 28.5 mg/g DCW and 52.1 mg/L.Conclusions
This study provided novel strategies for improving squalene yield and demonstrated the potential of producing squalene by E. coli.
SUBMITTER: Xu W
PROVIDER: S-EPMC6437923 | biostudies-literature | 2019
REPOSITORIES: biostudies-literature
Publications
Improving squalene production by enhancing the NADPH/NADP<sup>+</sup> ratio, modifying the isoprenoid-feeding module and blocking the menaquinone pathway in <i>Escherichia coli</i>.
Biotechnology for biofuels 20190328
<h4>Background</h4>Squalene is currently used widely in the food, cosmetics, and medicine industries. It could also replace petroleum as a raw material for fuels. Microbial fermentation processes for squalene production have been emerging over recent years. In this study, to study the squalene-producing potential of <i>Escherichia coli</i> (<i>E. coli)</i>, we employed several increasing strategies for systematic metabolic engineering. These include the expression of human truncated squalene syn ...[more]
