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Identifier |
000426493 |
Title |
Μελέτη της φωτοσυνθετικά ελεγχόμενης διαφοροποίησης του pH του περιβάλλοντος των μικροφυκών |
Alternative Title |
Study of the photosynthetic controlled pH differentiation of the microalgae environment |
Author
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Μέντε, Μελπομένη-Σοφία Δ.
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Thesis advisor
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Κοτζαμπάσης, Κυριάκος
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Reviewer
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Σαρρής, Παναγιώτης
Πυρίντσος, Στέργιος
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Abstract |
Photosynthesis is a biological process that converts solar energy into exploitable chemical energy,
which is invested in converting inorganic matter into organic.
In this paper we investigate how the photosynthetic process is affected and affects the proton
environment of the plant cell and how we can use these effects in various future biotechnological
applications. Thus, with the unicellular green alga Scenedesmus obliquus, we measured combined
the variations in environmental pH, cell volume (μl PCV/ml), photosynthetic efficiency (Fv / Fm),
and a number of other factors related to molecular structure and function of the photosynthetic
apparatus. Experiments were performed at different intensities of light and in the dark, at different
nutrient concentrations, at different cell concentrations, in open and closed cultures.
In the present work we showed that in acidic environments the photosynthesis and growth of
microalgae increased in relation to the corresponding alkaline one, especially when the
environment was saturated with nutrients and photons. Correspondingly, during photosynthesis in
all experimental treatments the pH increased, which indicates proton uptake. This variation of pH
in the existing literature has most often been related to the uptake and removal of CO2, although
in green algae (and not only) have identified a series of H+-channels, and some of them are
photoregulated. When keep the CO2 flow in open cultures constant, we saw a clear and sharp
increase in pH during photosynthesis while in the dark, in the absence of photosynthesis, the pH
remained constant. Taking these facts into consideration we can conclude that:
Photosynthesis of microalgae requires the absorption of protons resulting in a pH increase in
aquatic environment. The photosynthetic controlled pH increase in microalgal culture medium is
the result of cellular proton pumping (H+) rather than a decrease in the CO2 concentration in the
culture medium. The proton uptake during photosynthesis is proportional to cell concentration
and light intensity.
The high concentration of protons (low pH) in the aquatic environment, when light and inorganic
nutrients are not the limiting factor, strongly induces the photosynthetic process and consequently
the growth of the culture expressed as a packed cell volume.
The mitochondrial respiratory process, in the absence of photosynthetic activity, does not
substantially differentiate the culture pH, but when intensified by exogenous supplied glucose
significantly reduces the pH of the culture. The decrease in pH induced by the respiratory process is
a result of CO2 .
All of the above allow us to be optimistic that in the near future we will be able to exploit this
knowledge of the interaction of microalgae with their protonated environment in order to
understand and deal better with major environmental problems, such as ocean acidification and
eutrophication.
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Language |
Greek |
Subject |
Microalgae |
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Model selection |
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Photosynthesis |
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Respiration |
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Αναπνοή |
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Μικροφύκη |
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Φωτοσύνθεση |
Issue date |
2019-11-29 |
Collection
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School/Department--School of Sciences and Engineering--Department of Biology--Post-graduate theses
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Type of Work--Post-graduate theses
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Permanent Link |
https://elocus.lib.uoc.gr//dlib/2/0/2/metadata-dlib-1575365333-252964-14509.tkl
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Views |
348 |