Co-expression of Yeast and Arabidopsis Genes Enhances Triacylglycerol Accumulation in Phaeodactylum

Microalgae are promising sources for producing valuable products such as biofuel and essential fatty acids. However, there are still challenges impeding commercial production of microalgal products, such as low yield. The team of Nodumo Nokulunga Zulu from University of Goettingen aims to enhance triacylglycerol (TAG) accumulation in the diatom Phaeodactylum tricornutum strain Pt4 by co-expressing the ScDGA1 gene from yeast, and the oleosin protein 3 from Arabidopsis thaliana (AtOLEO3) in the strain.

Individual expression of ScDGA1 and AtOLEO3 in Pt4 resulted in significant increases in TAG levels compared to wild types. The co-expression of both genes was accompanied by an even greater increase in TAG content. Lines co-expressing ScDGA1 and AtOLEO3 also exhibited larger and increased number of lipid droplets compared to lines only expressing single genes. Under nitrogen stress, TAG productivity was further increased in comparison to nitrogen-rich conditions.

Co-expression of the two genes was revealed to be a more effective strategy for enhancing TAG accumulation in P. tricornutum strain Pt4 than a single gene strategy. This study also marks the first time an LD protein from a vascular plant, oleosin, was shown to have an impact on diatom TAG accumulation and on LD organization.