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NEUTRAL LIPID AND CARBOHYDRATE PRODUCTIVITIES AS A RESPONSE TO NITROGEN STATUS IN ISOCHRYSIS SP. (T-ISO; HAPTOPHYCEAE): STARVATION VERSUS LIMITATION1
Version of Record online: 10 MAY 2012
© 2012 Phycological Society of America
Journal of Phycology
Volume 48, Issue 3, pages 647–656, June 2012
How to Cite
Lacour, T., Sciandra, A., Talec, A., Mayzaud, P. and Bernard, O. (2012), NEUTRAL LIPID AND CARBOHYDRATE PRODUCTIVITIES AS A RESPONSE TO NITROGEN STATUS IN ISOCHRYSIS SP. (T-ISO; HAPTOPHYCEAE): STARVATION VERSUS LIMITATION. Journal of Phycology, 48: 647–656. doi: 10.1111/j.1529-8817.2012.01154.x
Received 2 July 2010. Accepted 12 March 2012.
- Issue online: 1 JUN 2012
- Version of Record online: 10 MAY 2012
- Accepted manuscript online: 24 MAR 2012 04:37AM EST
- neutral lipid;
- nitrogen limitation;
- nitrogen starvation phytoplankton;
Partitioning of the carbon (C) fixed during photosynthesis between neutral lipids (NL) and carbohydrates was investigated in Isochrysis sp. (Haptophyceae) in relation to its nitrogen (N) status. Using batch and nitrate-limited continuous cultures, we studied the response of these energy reserve pools to both conditions of N starvation and limitation. During N starvation, NL and carbohydrate quotas increased but their specific growth rates (specific rates of variation, μCAR and μNL) decreased. When cells were successively deprived and then resupplied with NO3, both carbohydrates and neutral lipids were inversely related to the N quota (N:C). These negative relationships were not identical during N impoverishment and replenishment, indicating a hysteresis phenomenon between N and C reserve mobilizations. Cells acclimated to increasing degrees of N limitation in steady-state chemostat cultures showed decreasing NL quota and increasing carbohydrate quota. N starvation led to a visible but only transient increase of NL productivity. In continuous cultures, the highest NL productivity was obtained for the highest experimented dilution rate (D = 1.0 d−1; i.e., for non N-limited growth conditions), whereas the highest carbohydrate productivity was obtained at D = 0.67 d−1. We used these results to discuss the nitrogen conditions that optimize NL productivities in the context of biofuel production.