Πειραματική μελέτη της παραγωγής ενζύμων και πολύ(υδροξυ αλκανοϊκών) εστέρων (PHAs) από θερμόφιλους και μεσόφιλους μικροοργανισμούς

• Main Authors: Kretza, Eirini-Aikaterini, Κρέτζα, Ειρήνη-Αικατερίνη
• Format: Doctoral or Postdoctoral Thesis
• Language: Greek
• Published: Aristotle University Of Thessaloniki (AUTH) 2011
• Subjects: Πολυ(υδροξυ αλκανοϊκά); Βιοπολυμερή; Λιπάση; Καθήλωση ενζύμων; Θερμοάντοχα ένζυμα; Polyhydroxyalkanoates (PHAs); Biopolymers; Lipase; Enzyme immobilization; Thermostable enzymes; Επιστήμες Μηχανικού και Τεχνολογία; Επιστήμη Χημικού Μηχανικού; Engineering and Technology; Chemical Engineering; Antarc*; Antarctica
• Online Access: http://hdl.handle.net/10442/hedi/30461; https://doi.org/10.12681/eadd/30461

In the present study, it was examined the microbial production of enzymes and biopolymers. The enzyme in study is lipase from the bacterium Thermus thermophilus HB8. For the increase of the lipase production it was examined the influence of the aeration and the carbon source. The better aeration increased the produced biomass and the intra-and extra-cellular lipase. For the examination of the effect of the carbon source, in the growth medium was added olive oil, sucrose and a combination of sucrose and olive oil. The oil increased the production of the biomass and the extracellular lipase while sucrose increased the produced intracellular lipase. The combination of the two carbon sources gave the best results of all cases since it increased the production of the biomass and total produced lipase. In order to characterize the biochemical properties of the Thermus thermophilus extracellular lipase, it was followed the following purification steps: precipitation with ammonium sulphate and ethanol and hydrophobic chromatography. The enzyme after the final purification step was quite clean and active. The molecular weight of the extracellular lipase is 56 kDa and is stable under neutral and alkaline environment and at high temperatures. In this study, it was also studied the immobilization of the commercial lipase Candida antarctica with physical adsorption on chitosan particles, with covalent bond on Eupergit ® C beads, and with encapsulation in alginates and alginate - polyvinyl alcohol particles. The immobilization of lipase on the chitosan particles resulted in a reduction of the enzyme activity, in contrast to the case of the encapsulation of lipase in the alginate particles where the enzyme activity was increased. In the second part of this study, it was examined the effect of different nutrients in the production of poly- (3-hydroxyalkanoates) from the bacterium Pseudomonas putida KT2442. Initially, it was studded the effect of two carbon sources (octanoic acid, glucose) in the production of PHA and it was ...