Translocation and de novo synthesis of eicosapentaenoic acid (EPA) during nitrogen starvation in Nannochloropsis gaditana

Jorijn H. Janssen; Packo P. Lamers; Ric C.H. de Vos; René H. Wijffels; Maria J. Barbosa

doi:10.1016/j.algal.2018.11.025

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Translocation and de novo synthesis of eicosapentaenoic acid (EPA) during nitrogen starvation in Nannochloropsis gaditana

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Translocation and de novo synthesis of eicosapentaenoic acid (EPA) during nitrogen starvation in Nannochloropsis gaditana

Jorijn H. Janssen, Packo P. Lamers, Ric C.H. de Vos, René H. Wijffels and Maria J. Barbosa

Algal research (Amsterdam), Vol.37, pp.138-144

01/2019

DOI: 10.1016/j.algal.2018.11.025

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Abstract

The microalga Nannochloropsis gaditana is known for accumulating fatty acids, including the commercially interesting eicosapentaenoic acid (EPA) within the polar lipids (PL) and neutral lipids (NL). During microalgal growth EPA is mainly present in the PL. Upon nitrogen starvation N. gaditana accumulates large amounts of TAG in lipid bodies. The neutral lipid fraction will mainly consist of triacylglycerol (TAG). When expressed per total cell dry weight, the NL-localized EPA increased while the PL-localized EPA decreased, suggesting that EPA is translocated from the PL into the NL lipids during nitrogen starvation. Here, we elucidated the origin of EPA in NL of N. gaditana by firstly growing this microalga under optimal growth conditions with 13CO2 as the sole carbon source followed by nitrogen starvation with 12CO2 as the sole carbon source. By measuring both 12C and 13C fatty acid isotope species in time, the de novo synthesized fatty acids and the already present fatty acids can be distinguished. For the first time, we proved that actual translocation of EPA from the PL into the NL occurs during nitrogen starvation of N. gaditana. Next to being translocated, EPA was synthesized de novo in both PL and NL during nitrogen starvation. EPA was made by carbon reshuffling within the cell as well. EPA was the main fatty acid translocated, suggesting that the enzyme responsible for fatty acid translocation has a high specificity for EPA. [Display omitted] •Carbon labeling (13C) was used to measure carbon flux during nitrogen starvation.•Translocation of eicosapentaenoic acid (EPA) from polar to neutral lipids was measured.•23% of all EPA present in neutral lipids was translocated from polar lipids.•De novo synthesis of EPA during nitrogen starvation was measured.•EPA in neutral lipids was partially synthesized by carbon reshuffling.

13C isotope

Eicosapentaenoic acid

Nannochloropsis gaditana

Polar lipids

Translocation

Triacylglycerol

Details

Title: Subtitle: Translocation and de novo synthesis of eicosapentaenoic acid (EPA) during nitrogen starvation in Nannochloropsis gaditana
Creators: Jorijn H. Janssen - Wageningen University & Research
Packo P. Lamers - Wageningen University & Research
Ric C.H. de Vos - Wageningen University & Research
René H. Wijffels - Nord University
Maria J. Barbosa - Bioprocess Engineering, AlgaePARC, Wageningen University and Research, P.O. Box 16, 6700 AA Wageningen, the Netherlands
Resource Type: Journal article
Publication Details: Algal research (Amsterdam), Vol.37, pp.138-144
DOI: 10.1016/j.algal.2018.11.025
ISSN: 2211-9264
eISSN: 2211-9264
Publisher: Elsevier B.V
Grant note: DOI: 10.13039/501100004963, name: Seventh Framework Programme, award: 613588
Language: English
Date published: 01/2019
Academic Unit: International Programs; Spanish and Portuguese
Record Identifier: 9984398007502771

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