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Online monitoring of chlorophyll a fluorescence in Nannochloropsis oceanica to assess photochemical changes and the onset of lipid accumulation during nitrogen deprivation
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  • Mariana Carneiro,
  • Graziella Chini Zittelli,
  • Bernardo Cicchi,
  • Elefterios Touloupakis,
  • Cecilia Faraloni,
  • Inês Maia,
  • Hugo Pereira,
  • Tamára Santos,
  • Francisco Xavier Malcata,
  • Ana Otero,
  • João Varela,
  • Giuseppe Torzillo
Mariana Carneiro

Corresponding Author:[email protected]

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Graziella Chini Zittelli
National Research Council
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Bernardo Cicchi
National Research Council Department of Biological Agricultural and Food Sciences
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Elefterios Touloupakis
National Research Council Department of Earth System Science and Environment Technologies
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Cecilia Faraloni
National Research Council Department of Biological Agricultural and Food Sciences
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Inês Maia
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Hugo Pereira
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Tamára Santos
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Francisco Xavier Malcata
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Ana Otero
Universidade de Santiago de Compostela
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João Varela
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Giuseppe Torzillo
Centro de Investigación en Ciencias del Mar y Limnologia
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In this work, we applied online chlorophyll a fluorescence measurements to monitor the changes in the photochemical parameters both in nitrate-deplete and nitrate-replete cultures of Nannochloropsis oceanica, in addition to biochemical parameters such as growth, lipid, fatty acid, and pigment contents. Under nitrate-replete conditions, growth was promoted along with pigment content, while total lipid content and fatty acid saturation level diminished. Under nitrate-deplete conditions, cultures showed an increased de-epoxidation state of the xanthophyll cycle pigments. Fast transients revealed a poor processing efficiency for electron transfer beyond QA, which was in line with the low electron transport rate due to nitrate depletion. Lipid content and the de-epoxidation state were the first biochemical parameters triggered by the change in nutrient status, which coincided with a 20% drop in the online effective quantum yield of PSII (ΔF/Fm’), and a raise in the Vj measurements. A good correlation was found between the changes in ΔF/Fm’ and lipid content (r=-0.96, p<0.01). The results confirm the reliability and applicability of online fluorescence measurements to monitor lipid induction in N. oceanica.
18 May 2021Submitted to Biotechnology and Bioengineering
19 May 2021Submission Checks Completed
19 May 2021Assigned to Editor
21 May 2021Reviewer(s) Assigned
19 Jun 2021Review(s) Completed, Editorial Evaluation Pending
19 Jun 2021Editorial Decision: Revise Major
13 Jul 20211st Revision Received
14 Jul 2021Submission Checks Completed
14 Jul 2021Assigned to Editor
14 Jul 2021Reviewer(s) Assigned
17 Jul 2021Review(s) Completed, Editorial Evaluation Pending
17 Jul 2021Editorial Decision: Accept