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Identifier 000375974
Title Επίδραση της έλλειψης του καλίου και του θείου στη φωτοσυνθετική παραγωγή υδρογόνου από του χλωροφύκος Scenedesmus obliquus
Alternative Title Effect of potassium and sulfur deficiency on the photosynthetic hydrogen production of the green algae Scenedesmus obliquus
Author Σταματάκης, Κωνσταντίνος Μιχ.
Thesis advisor Κοτζαμπάσης, Κυριάκος
Reviewer Γανωτάκης, Δήμητριος
Τσαγρή, Ευθυμία
Abstract The continually expanding interest for the use of hydrogen as fuel has made renewable hydrogen production from green algae a research option with important future applications. Photochemical production of molecular hydrogen under anaerobic condition has first been documented by Gaffron (1939). The next important milestone has been the the manipulation of growth conditions in green algae cultures so as to produce a greater amount of hydrogen (Melis et al, 2000). In the present study the effect of various ion depletions (Ca, Cl, K, N, Mg, S, P, Fe, Mn, Zn, Cu και Na) and light intensities (200 μmol m-2 s-1, 100 μmol m-2 s-1, 50 μmol m-2 s-1 and darkness) on hydrogen production has been studied on mixotrophic cultures of Scenedesmus obliquus. The experiments that took place revealed that the depletion of the elements K, Mn, Cu, Cl, S, Zn, Cu, P and Mg from the nutrient solution leads to substantially elevated hydrogen production, with K deficiency being responsible for the greatest amount of H2 measured. Also, in the mixotrophic cultures of Scenedesmus oblicuus, light intensity is inversely proportional to H2 production. The ideal light intensity for maximum H2 production was found to be 50 μmol m-2 s-1, where the Kdeficient cultures produced 1,11 L H2/L PCV, as opposed to the Sdeficient and control cultures which produced 0,64 L H2/L PCV and 0,5 L H2/L PCV respectively. The presence of glucose and secondarily the absence of K ions led to the differentiation of the photosynthetic mechanism (decrease of PSII reaction centers, increase of functional photosynthetic antennas, decrease of photochemical quenching) which in turn led to the dramatic decrease of photosynthetic efficiency and the increase of respiration. As a result, anoxic conditions were established within 24 hours in sealed cultures, resulting in the induction of hydrogenases and the subsequent production of hydrogen. Cultures deficient in K and S primarily utilized the NPQR pathway of hydrogen production, in which PSI is essential. This was confirmed by the substantial decrease of PSII/PSI rate in the aforementioned cultures as compared to the control culture (complete culture medium with no depletions).
Language Greek
Subject Θείο
Issue date 2012-11-16
Collection   School/Department--School of Sciences and Engineering--Department of Biology--Post-graduate theses
  Type of Work--Post-graduate theses
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