Bestimmung physikalisch-chemischer Eigenschaften von Alginatlösungen und -gelen und von Lösungen extrazellulärer polymerer Substanzen von Pseudomonas aeruginosa SG81 mit der Analytischen Ultrazentrifuge - Determination of physico-chemical properties of alginate solutions and gels and of solutions of extracellular polymer substances of Pseudomonas aeruginosa by means of analytical ultracentrifugation

by Straatmann, Andrea

The extracellular polymer substances (EPS) of Pseudomonas aeruginosa, alginate isolated from this EPS and an algal alginate were examined with analytical ultracentrifugation. The samples were dissolved in isotonic sodium chloride solution to avoid disturbance of the measurements due to polyelectrolyte effects. The sedimentation and diffusion coefficients were determined from velocity runs. Evaluation of sedimentation-diffusion equilibrium at medium centrifugal fields yielded molar masses and the second osmotic virial coefficients. The aim of this thesis was to determine differences in the thermodynamic properties of the polymers, the effect of acetylic groups on the aggregation of alginates and the influence of alginate on the stability of EPS. Additionally the gelation of alginates with calcium ions was examined both with an analytical ultracentrifuge and a dynamic oscillating rheometer.