Photosynthesis in Diatoms

Scarsini, Matteo; Marchand, Justine; Manoylov, Kalina M.; Schoefs, Benoı̂t

doi:10.1002/9781119370741.ch8

Cited by 12 publications

(9 citation statements)

References 107 publications

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“…Light harvesting complex (LHC) proteins are functional components of photosystems having different functions including light harvesting, photosystem regulation, and photoprotection (Bassi and Caffarri, 2001 ; Scarsini et al, 2019 ). In NS, most of the LHC genes were downregulated with few exceptions including LHCX4 and LHCR10 .…”

Section: Resultsmentioning

confidence: 99%

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The Transition Toward Nitrogen Deprivation in Diatoms Requires Chloroplast Stand-By and Deep Metabolic Reshuffling

et al. 2022

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Microalgae have adapted to face abiotic stresses by accumulating energy storage molecules such as lipids, which are also of interest to industries. Unfortunately, the impairment in cell division during the accumulation of these molecules constitutes a major bottleneck for the development of efficient microalgae-based biotechnology processes. To address the bottleneck, a multidisciplinary approach was used to study the mechanisms involved in the transition from nitrogen repletion to nitrogen starvation conditions in the marine diatom Phaeodactylum tricornutum that was cultured in a turbidostat. Combining data demonstrate that the different steps of nitrogen deficiency clustered together in a single state in which cells are in equilibrium with their environment. The switch between the nitrogen-replete and the nitrogen-deficient equilibrium is driven by intracellular nitrogen availability. The switch induces a major gene expression change, which is reflected in the reorientation of the carbon metabolism toward an energy storage mode while still operating as a metabolic flywheel. Although the photosynthetic activity is reduced, the chloroplast is kept in a stand-by mode allowing a fast resuming upon nitrogen repletion. Altogether, these results contribute to the understanding of the intricate response of diatoms under stress.

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Section: Resultsmentioning

confidence: 99%

“…Simultaneously, genes encoding for the carotenoid biosynthesis were downregulated in NS. Moreover, lowering the N availability triggered a reduction of the transcripts levels corresponding to two main key enzymes of the xanthophyll cycle, violaxanthin de/epoxidase, and zeaxanthin epoxidase (Scarsini et al, 2019 ).…”

Section: Resultsmentioning

confidence: 99%

The Transition Toward Nitrogen Deprivation in Diatoms Requires Chloroplast Stand-By and Deep Metabolic Reshuffling

et al. 2022

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“…One is a “biophysical CCM” in which CO 2 and HCO 3 - are transported by CAs and bicarbonate transporters. The other CCM is called “biochemical CCM” and involves a prefixation of inorganic carbon into C4 compounds as in C4 land plants, and then a conversion into C3 compounds and CO 2 in proximity of RuBisCO favoring its carboxylation activity (Scarsini et al, 2019). Although the existence of a functional biochemical CCM was reported in Conticribra weissflogii (Grunow) Stachura-Suchoples & D.M.…”

Section: Discussionmentioning

confidence: 99%

Carbon Orientation in the Diatom Phaeodactylum tricornutum: The Effects of Carbon Limitation and Photon Flux Density

et al. 2019

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Diatoms adapt to changing environmental conditions in very efficient ways. Among the mechanisms that can be activated, the reorientation of carbon metabolism is crucial because it allows the storage of energy into energy-dense molecules, typically lipids. Beside their roles in physiology, lipids are commercially interesting compounds. Therefore studies dealing with this topic are relevant for both basic and applied science. Although the molecular mechanisms involved in the reorientation of carbon metabolism as a response to a deficiency in nutrients such as nitrogen or phosphorus has been partially elucidated, the impacts of carbon availability on the implementation of the reorientation mechanisms remain unclear. Indeed, it has not been determined if the same types of mechanisms are activated under carbon and other nutrient deficiencies or limitations. The first aim of this work was to get insights into the physiological, biological and molecular processes triggered by progressive carbon starvation in the model diatom Phaeodactylum tricornutum . The second aim was to investigate the effects of the growth light intensity on these processes. For such a purpose three different photon flux densities 30, 300, and 1000 μmol photons m -2 s -1 were used. The results presented here demonstrate that under carbon limitation, diatom cells still reorient carbon metabolism toward either phospho enol pyruvate or pyruvate, which serves as a hub for the production of more complex molecules. The distribution of carbon atoms between the different pathways was partially affected by the growth photon flux density because low light (LL) provides conditions for the accumulation of chrysolaminarin, while medium light mostly stimulated lipid synthesis. A significant increase in the amount of proteins was observed under high light (HL).

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“…The increase of human populations, the reduction of farmland and the expansion of cities contribute to an accelerated depletion of natural resources to a point that finding alternative sources of natural resources, including biomolecules, is becoming crucial. Microalgae are a promising feedstock for the production of biomolecules belonging to the major organic macromolecules classes ( Mimouni et al, 2012 ) while utilizing sun energy through the photosynthetic process ( Scarsini et al, 2019 ). In addition, microalga culture does not require farmland, reducing the competition for space with other farm productions ( Gordon et al, 2019 ).…”

Section: Introductionmentioning

confidence: 99%

Metabolite Quantification by Fourier Transform Infrared Spectroscopy in Diatoms: Proof of Concept on Phaeodactylum tricornutum

et al. 2021

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Diatoms are feedstock for the production of sustainable biocommodities, including biofuel. The biochemical characterization of newly isolated or genetically modified strains is seminal to identify the strains that display interesting features for both research and industrial applications. Biochemical quantification of organic macromolecules cellular quotas are time-consuming methodologies which often require large amount of biological sample. Vibrational spectroscopy is an essential tool applied in several fields of research. A Fourier transform infrared (FTIR) microscopy-based imaging protocol was developed for the simultaneous cellular quota quantification of lipids, carbohydrates, and proteins of the diatom Phaeodactylum tricornutum. The low amount of sample required for the quantification allows the high throughput quantification on small volume cultures. A proof of concept was performed (1) on nitrogen-starved experimental cultures and (2) on three different P. tricornutum wild-type strains. The results are supported by the observation in situ of lipid droplets by confocal and brightfield microscopy. The results show that major differences exist in the regulation of lipid metabolism between ecotypes of P. tricornutum.

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Photosynthesis in Diatoms

Cited by 12 publications

References 107 publications

The Transition Toward Nitrogen Deprivation in Diatoms Requires Chloroplast Stand-By and Deep Metabolic Reshuffling

The Transition Toward Nitrogen Deprivation in Diatoms Requires Chloroplast Stand-By and Deep Metabolic Reshuffling

Carbon Orientation in the Diatom Phaeodactylum tricornutum: The Effects of Carbon Limitation and Photon Flux Density

Metabolite Quantification by Fourier Transform Infrared Spectroscopy in Diatoms: Proof of Concept on Phaeodactylum tricornutum

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