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Identifier

000451939

Title

Επίδραση ακραίων συγκεντρώσεων CO2 και NaCl στη μοριακή δομή και λειτουργία του φωτοσυνθετικού μηχανισμού του μικροφύκους Chlorella vulgaris

Alternative Title

Εffect of extreme concentrations of CO2 and NaCl in the molecular structure and function of the photosynthetic apparatus of the microalga Chlorella vulgaris

Author

Μαραγκουδάκης, Αριστείδης Γ.

Thesis advisor

Κοτζαμπάσης, Κυριάκος

Reviewer

Πυρίντσος, Στέργιος
Σαρρής, Παναγιώτης

Abstract

The current study examines the functional and metabolic differentiation of the unicellular eukaryotic microalga Chlorella vulgaris as well as the choice of strategy response under extreme concentrations of salinity [600mM NaCl – 3.5%(w/v) NaCl] and CO₂(30%). Based on the results of this study, it appears that the microalga uses an osmoregulatory mechanism where as a first response, the first minutes of osmotic stress, a cellshrinkage (reduction of cell volume) is observed and a sharp increase in carbohydrate content (which act as osmolytes) work together to retain cell viability and functionality under extreme salinity (3.5%NaCl). Furthermore, extreme salinity contributes to the induction of the Na⁺ /H⁺ antiporter resulting in the controlled absorption of significant amounts of sodium ions, based on the recordings of the electrical conductivity and pH of the medium. Combined, these responses of the cell lead to the moderation of the intracellular osmotic pressure and its protection from plasmolysis. Fluorescence induction measurements, along with photosynthetic and respiratory activities revealed that extreme CO₂concentrations in combination with extreme salinity act as stress relief, significantly increasing the photosynthetic activity, while the production of carbohydrates and lipids was also favored. Under these conditions, high photosynthetic activity (which is associated with H⁺ uptake from the medium) competed with the activity of the Na⁺ /H⁺ antiporter and consequently, Na⁺ absorption is reduced and the cellular concentration of carbohydrates is increased, during osmoregulation. Therefore, bearing in mind the bioenergetic strategy followed by the microalga to manage to highly stressful conditions, (exposure to extreme concentrations of CO₂and NaCl), paves the way for numerous biotechnological applications while simultaneously addressing important environmental issues such as global warming and the Freshwater Salinization Syndrome (FSS) which leads to the deprivation of drinking water.

Language

Greek

Subject

Environmental biotechnology

Freshwater salnization

Global warming

Photosynthesis

Αλάτωση γλυκού νερού

Περιβαλλοντική βιοτεχνολογία

Υπερθέρμανση του πλανήτη

Φωτοσύνθεση

Issue date