Light-dependent utilization of two radiolabelled carbon sources, sodium bicarbonate and sodium acetate, and relationships with long chain polyunsaturated fatty acid synthesis in the microalga Pavlova lutheri (Haptophyta) - Le Mans Université Accéder directement au contenu
Article Dans Une Revue European Journal of Phycology Année : 2011

Light-dependent utilization of two radiolabelled carbon sources, sodium bicarbonate and sodium acetate, and relationships with long chain polyunsaturated fatty acid synthesis in the microalga Pavlova lutheri (Haptophyta)

Résumé

Pavlova lutheri is a common member of the Pavlovophyceae (Haptophyta), often used as a food source for aquatic filter-feeders and cultured in laboratories to produce high levels of polyunsaturated fatty acids (PUFAs), especially eicosapentaenoic and docosahexaenoic acids (EPA and DHA, respectively), which are known to have benefits for human health. Consequently, we investigated the pathways involved in the biosynthesis of long chain polyunsaturated fatty acids (LC-PUFAs) in this alga during photosynthesis in relation to light intensity. Using two radiolabelled carbon sources, [14C] sodium bicarbonate and [1-14C] sodium acetate, we obtained data suggesting that P. lutheri is able to synthesize LC-PUFAs by successive elongation and desaturation steps. It converts palmitic acid into palmitoleic acid by Δ7-desaturation. Moreover, significant incorporation of [1-14C] acetate (organic carbon) and its subsequent use in lipid metabolism suggest that P. lutheri may have a mixotrophic capacity for carbon assimilation. Synthesis of lipids, including galactolipids and phospholipids, increased with light intensity when the cells were incubated with [14C] bicarbonate (inorganic carbon), but was less sensitive to differences in light intensity when incubated with [1-14C] acetate, a heterotrophic carbon source that stimulates the synthesis of monounsaturated fatty acids, such as oleic acid. In the case of n-3 fatty acids, EPA and DHA synthesis was lower at high light (340 µmol photons m−2 s−1) with the [14C] bicarbonate, but did not vary with [1-14C] acetate. Finally, P. lutheri seems to have two distinct enzyme pools involved in LC-PUFA synthesis, one is intra-chloroplastidic and dependent on light intensity, and the other is extra-chloroplastidic and independent of light.

Dates et versions

hal-02001099 , version 1 (31-01-2019)

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Citer

Freddy Guihéneuf, Lionel Ulmann, Gerard Tremblin, Virginie Mimouni. Light-dependent utilization of two radiolabelled carbon sources, sodium bicarbonate and sodium acetate, and relationships with long chain polyunsaturated fatty acid synthesis in the microalga Pavlova lutheri (Haptophyta). European Journal of Phycology, 2011, 46 (2), pp.143-152. ⟨10.1080/09670262.2011.577912⟩. ⟨hal-02001099⟩
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