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Title Μελέτη της ακραιόφιλης συμπεριφοράς του λειχήνα Pleurosticta acetabulum σε διαφορετικές ακραίες θερμοκρασίες διατηρώντας τη μεταβολική του δυνατότητα να παράγει υδρογόνο
Author Τζιβράς, Γεράσιμος
Thesis advisor Κοτζαμπάσης, Κυριάκος
Abstract Lichens are micro-ecosystems created by the symbiosis of a fungus and an alga or cyanobacterium. These micro-ecosystems have the ability to expel their moisture, transitioning into an inactive state in order to protect themselves from adverse environmental conditions. Previous studies have shown the ability of lichens to survive in a plethora of extreme conditions. The current work focuses on studying the tolerance of the dehydrated lichen Pleurosticta acetabulum to different extreme temperatures (-196°C, -86°C, -20°C, +5.7°C, +25°C, +60°C, and +70°C). Furthermore, the combined exposure to extreme temperatures with the extreme UVB radiation (1,7mW/cm2 = 1000 J/m2*min for 70 hours) was also studied. In all cases, we examined the lichen’s ability to survive, while fully maintaining its functionality, and production of molecular hydrogen in closed systems after the establishment of anoxic/anaerobic conditions (due to the lichens’ intense respiratory activity). The viability of the lichen was evaluated based on the molecular structure and function of the photosynthetic apparatus via fluorescence induction measurements (OJIP-test), while the hydrogen production was measured using thermal conductivity gas chromatography (GC-TCD). Our results showed that the lichen was regenerated successfully, while simultaneously maintaining its functionality and its capacity for molecular hydrogen production in all of the aforementioned treatments. We, therefore, conclude that lichens can survive in a temperature range from -196°C to +70°C as well as in a combination of these extreme temperatures and exposure to vacuum and extreme UVB radiation. Their survivability and the complete preservation of their functionality combined with their capacity for molecular hydrogen production allow the use of lichens in future biotechnological applications, even in the extreme environments of other planets, paving the way for astrobiological and astrobiotechnological applications.
Language Greek
Issue date 2022-03-28
Collection   School/Department--School of Sciences and Engineering--Department of Biology--Graduate theses
  Type of Work--Graduate theses
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