Bacterial attachment and aggregation play a vital role in both the formation of biofilm and the removal of undesired biofilms from mineral surfaces. The binding forces involved in this process consist of weak interactions, such as Vander Waals's forces and electrostatic interactions. Although attachment of bacterial cells to mineral surfaces is mainly governed by exopolymer alginate, lipopolysaccharide chemistry seems to play a role in adherence and biofilm accumulation. The project aims to use the synthetic poly (acrylic acid) (PAA) as a model for more complicated biopolymers. Because macromolecules are non-fluorescent, they have been covalently attached with fluorophores, such as ACE, AMMA and AmNS. In an effort to understand the Cell-Mineral Interface process more fully, spectroscopic techniques have been used to investigate conformation and dynamics for PAA, alginate, and lipopolysaccharide (LPS) in both, bulk solution and onto alumina and silica surfaces, which should act as model systems for bacterial growth. Initial solution dynamics of these macromolecules show that the model polymer and biopolymers exhibit partially coiled conformations at low pH values, but adopt a relatively expanded shape from around pH more than their pKa. The addition of simple electrolytes like NaCl and CaCl2 to either system encourages the coiling of the polymer chain at high pH values. Furthermore, adding calcium chloride causes a much tighter coil, and PAA is the most ionic strength responsive polyelectrolyte. A combination of fluorescence and ICP-MS demonstrated that PAA had a strong adsorption affinity for A12O3, in contrast to the alginate and LPS adsorb weakly to the surface. And all polymers attract feebly to the SiO2. The adsorption process is pH dependent: strong adsorption was observed at low pH. The dependence of adsorption on the minerals (A12O3 and SiO2) concentration was also examined at different pH conditions: the adsorption amount was observed to increase by increasing the solid concentration. Adsorption isotherms obtained at low and high mineral concentrations were found to be Henry in type.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:577401 |
| Date | January 2013 |
| Creators | Belkasem, Elfateh |
| Contributors | Swanson, Linda |
| Publisher | University of Sheffield |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://etheses.whiterose.ac.uk/4120/ |
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