Overexpression of an endogenous type 2 diacylglycerol acyltransferase in the marine diatom Phaeodactylum tricornutum enhances lipid production and omega-3 long-chain polyunsaturated fatty acid content

A - Papers appearing in refereed journals

Haslam, R. P., Hamilton, M. L., Economou, C., Smith, Richard T., Hassall, K. L., Napier, J. A. and Sayanova, O. V. 2020. Overexpression of an endogenous type 2 diacylglycerol acyltransferase in the marine diatom Phaeodactylum tricornutum enhances lipid production and omega-3 long-chain polyunsaturated fatty acid content . Biotechnology for Biofuels. 13 (87). https://doi.org/https://doi.org/10.1186/s13068-020-01726-8

AuthorsHaslam, R. P., Hamilton, M. L., Economou, C., Smith, Richard T., Hassall, K. L., Napier, J. A. and Sayanova, O. V.
Abstract

Background: Oleaginous microalgae represent a valuable resource for the production of high-value molecules. Considering the importance of omega-3 long-chain polyunsaturated fatty acids (LC-PUFAs) for human health and nutrition the yields of high-value eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) require significant improvement to meet demand; however, the current cost of production remains high. A promising approach is to metabolically engineer strains with enhanced levels of triacylglycerols (TAGs) enriched in EPA and DHA.
Results: Recently, we have engineered the marine diatom Phaeodactylum tricornutum to accumulate enhanced levels of DHA in TAG. To further improve the incorporation of omega-3 LC-PUFAs in TAG, we focused our effort on the identification of a type 2 acyl-CoA:diacylglycerol acyltransferase (DGAT) capable of improving lipid production and the incorporation of DHA in TAG. DGAT is a key enzyme in lipid synthesis. Following a diatom based in vivo screen of candidate DGATs, a native P. tricornutum DGAT2B was taken forward for detailed characterisation. Overexpression of the endogenous P. tricornutum DGAT2B was confirmed by qRT-PCR and the transgenic strain grew successfully in comparison to wildtype. PtDGAT2B has broad substrate specificity with preferences for C16 and LC-PUFAs acyl groups. Moreover, the overexpression of an endogenous DGAT2B resulted in higher lipid yields and enhanced levels of DHA in TAG. Furthermore, a combined overexpression of the endogenous DGAT2B and ectopic expression of a Δ5-elongase showed how iterative metabolic engineering can be used to increase DHA and TAG content, irrespective of nitrogen treatment.
Conclusion: This study provides further insight into lipid metabolism in P. tricornutum and suggests a metabolic engineering approach for the efficient production of EPA and DHA in microalgae.

KeywordsAcyl-CoA:diacylglycerol acyltransferase (DGAT); Eicosapentaenoic acid; Docosahexaenoic acid; Triacylgycerol; Omega-3 fatty acids; Phaeodactylum tricornutum
Year of Publication2020
JournalBiotechnology for Biofuels
Journal citation13 (87)
Digital Object Identifier (DOI)https://doi.org/https://doi.org/10.1186/s13068-020-01726-8
Open accessPublished as ‘gold’ (paid) open access
FunderBiotechnology and Biological Sciences Research Council
Funder project or codeMultifunctionalized Microalgae - A novel and flexible platform technology for maximising feed/energy conversion and treating severe infections in livestock [TPM]
Publisher's version
Output statusPublished
Publication dates
Print14 May 2020
Publication process dates
Accepted08 May 2020
ISSN1754-6834
PublisherBiomed Central Ltd

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