Bioenergetic reprogramming plasticity under nitrogen depletion by the unicellular green alga Scenedesmus obliquus

Cellular energy management includes “rational” planning and operation of energy production and energy consumption units. Microalgae seem to have the ability to calculate their energy reserves and select the most profitable bioenergetic pathways. Under oxygenic mixotrophic conditions, microalgae inve...

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Bibliographic Details
Published inPlanta Vol. 247; no. 3; pp. 679 - 692
Main Authors Papazi, Aikaterini, Korelidou, Anna, Andronis, Efthimios, Parasyri, Athina, Stamatis, Nikolaos, Kotzabasis, Kiriakos
Format Journal Article
LanguageEnglish
Published Berlin/Heidelberg Springer Science + Business Media 01.03.2018
Springer Berlin Heidelberg
Springer Nature B.V
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Summary:Cellular energy management includes “rational” planning and operation of energy production and energy consumption units. Microalgae seem to have the ability to calculate their energy reserves and select the most profitable bioenergetic pathways. Under oxygenic mixotrophic conditions, microalgae invest the exogenously supplied carbon source (glucose) to biomass increase. If 3,4-dichlorophenol is added in the culture medium, then glucose is invested more to biodegradation rather than to growth. The biodegradation yield is enhanced in nitrogen-depleted conditions, because of an increase in the starch accumulation and a delay in the establishment of oxygen-depleted conditions in a closed system. In nitrogen-depleted conditions, starch cannot be invested in PSII-dependent and PSII-independent pathways for H₂-production, mainly because of a strong decrease of the cytochrome b₆f complex of the photosynthetic electron flow. For this reason, it seems more profitable for the microalga under these conditions to direct the metabolism to the synthesis of lipids as cellular energy reserves. Nitrogendepleted conditions with exogenously supplied 3,4-dichlorophenol induce reprogramming of the microalgal bioenergetic strategy. Cytochrome b₆f is strongly synthesized (mainly through catabolism of polyamines) to manage the electron bypass from the dichlorophenol biodegradation procedure to the photosynthetic electron flow (at the level of PQ pool) and consequently through cytochrome b₆f and PSI to hydrogenase and H₂-production. All the above showed that the selection of the appropriate cultivation conditions is the key for the manipulation of microalgal bioenergetic strategy that leads to different metabolic products and paves the way for a future microalgal “smart” biotechnology.
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ISSN:0032-0935
1432-2048
DOI:10.1007/s00425-017-2816-3