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Dissertation angenommen durch: Universität Duisburg-Essen, Standort
Duisburg, Fakultät für Naturwissenschaften, Institut für Chemie,
2003-07-02
BetreuerIn: Prof. Dr. Christian Mayer , Universität Duisburg-Essen, Standort Duisburg, Fakultät für Naturwissenschaften, Institut für Chemie
GutachterIn: Prof. Dr. Christian Mayer , Universität Duisburg-Essen, Standort Duisburg, Fakultät für Naturwissenschaften, Institut für Chemie GutachterIn:
Prof. Dr. Werner Borchard , Universität Duisburg-Essen, Standort
Duisburg, Fakultät für Naturwissenschaften, Institut für Chemie
Schlüsselwörter in Deutsch: Alginat, Biofilm, Pseudomonas aeruginosa, Egg-box Modell, 13C-NMR
Schlüsselwörter in Englisch: alginate, biofilm, egg-box model, Pseudomonas aeruginosa, 13C-NMR
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Abstrakt in Englisch
The investigation of weak interactions within biofilms of P. aeruginosa
SG81 and its isolates (EPS, alginate) show a strong relationship
between the mechanical properties of the biofilm and the aqueous
solvent (e.g. pH value, ionic strengh, presence of mono- or bivalent
cations). Comparing the C-5 resonance lines of 13C- NMR spectra within
a Li - concentration series with simulated spectra, a rapid decrease of
the correlation time even at low ionic strengh is clearly observed.
Therefore, the addition of monovalent counterions reduces the
intramolecular electrostatic interactions between adjacent carboxyl
groups within the polysaccharide. This results in a further
entanglement of the macromolecule. Regarding bivalent counterions,
significant differences with regard to the degree of interactions of
the examined species (Mg2 , Ca2 ) with the alginate could be observed.
Mg2 ions show rather weak and non-specific interactions towards
bacterial alginates, whereas Ca2 ions indicate a specific binding
behaviour. In addition to this, a new model for the binding of Ca2 ions
to bacterial alginate was proposed on the basis of NMR- measurements in
the presence of paramagnetic ions (Mn2 ). Furthermore, the effects of
stress factors (nutrient or oxygen depletion)on biofilm structure have
been investigated in a long-term in vivo experiment. It was shown, that
the mechanical stability of a biofilm under these environmental
conditions is rapidly decreased due to the release of alginate lyase.
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