Αλληλεπιδράσεις του φωτοσυνθετικού μηχανισμού των μικροφυκών με το εξωκυτταρικό περιβάλλον, το ηλεκτρικό πεδίο και το υδρογόνο: βιοτεχνολογικές προοπτικές

• Main Authors: Zerveas, Sotirios, Ζερβέας, Σωτήριος
• Format: Doctoral or Postdoctoral Thesis
• Language: Greek
• Published: University of Crete (UOC) 2023
• Subjects: Στάση; Στάση μεταβολισμού; Φωτοσύνθεση υπό την επίδραση ηλεκτρικού πεδίου; Πρόσληψη πρωτονίων κατά την φωτοσύνθεση; Θεμελιώδη φορτία; Ηλεκτροβιολογία; Φυτά σε διάφορες ατμόσφαιρες; Φαινόμενο θερμοκηπίου; Οξίνιση ωκεανών; Stasis; Metabolic stasis; Photosynthesis under electrical field; Photosynthetic proton uptake; Fundamental electric charges; Electrobiology; Plants under variable atmospheric mixtures; Greenhouse efect; Oceans acidification; Βιολογία; Φυσικές Επιστήμες; Βιοχημεία και Μοριακή βιολογία; Βιοτεχνολογία; Biological Sciences; Natural Sciences; Biochemistry and Molecular Biology; Biotechnology; Ocean acidification
• Online Access: http://hdl.handle.net/10442/hedi/55206; https://doi.org/10.12681/eadd/55206

The interactions of the photosynthetic process and in general the cellular metabolism of microalgae with the extracellular water environment (exchange of H+ and e- - Chapters I and II) and their gaseous environment (exposure to extreme atmospheres, oxygenic and anoxic - Chapters III and IV ), are presented and thoroughly analyzed in the four chapters of this Doctoral Thesis: CHAPTER I: The microalgae photosynthetic process and the extracellular proton environment interact with each other. The photosynthetic process of microalgae causes an increase in pH in the culture medium as a result of cellular proton pumping rather than the effect of CO2fixation. Photosynthetic water photolysis and the plastoquinone reduction/oxidation cycle provide protons in the lumen. Biological weak bases, such as polyamines, act as "permeable buffers" in the lumenduring the photosynthetic process, converting ΔpH to Δψ. This is probably the main reason for the continuous light-driven uptake of protons from the culture medium, through the cytoplasm and stroma, into the lumen. The rate of proton uptake and thus microalgal growth is proportional to light intensity, cell concentration, and extracellular proton concentration. Low pH in microalgal cultures, without light and nutrient limitations, strongly induces photosynthesis (and proton uptake) and, consequently, growth. In contrast, the mitochondrial respiratory process, in the absence of photosynthetic activity, does not substantially changethe pH of the culture. The intensification of the respiration process by exogenous supply of glucose leads to significantly reduced pH values in the culture medium, almost exclusively through the production of protons. Increased concentrations of atmospheric CO2 dissolves in the water causing the "ocean acidification" effect by inhibiting the calcification process, very important for many phytoplankton and zooplankton organisms, but also for corals. The proposed new approach to the interaction of microalgal photosynthetic activity with proton ...