Dissertation
PROBING THE MOLECULAR MECHANISMS OF PATHOGENIC AND NON-PATHOGENIC LISTERIA ADHERENCE THROUGH SURFACE BIOPOLYMERS
Doctor of Philosophy (PhD), Washington State University
01/2010
Handle:
https://hdl.handle.net/2376/2801
Abstract
Atomic force microscopy (AFM) has been used to probe some of the biophysical properties of virulent and avirulent Listeria. In the first study, the relationship between the pathogenic L. monocytogenes in vitro adhesion to a model inert surface and their in vivo virulence was investigated. Our results indicated that the nanoscale adhesion forces quantified between eight L. monocytogenes strains that varied in their virulence and silicon nitride in water were logarithmically correlated with strains' virulence. In the second study, the relationship between adherence and virulence was investigated across the genus Listeria. In addition, the heterogeneities in the adhesion measurements were quantified and correlated with the ex vivo bacterial adhesion and the in vivo virulence. Our results indicated that virulent Listeria species were characterized by significantly larger adhesion energies to silicon nitride compared to those of the avirulent species. The heterogeneities in the femto-Joule adhesion energies quantified between bacterial strains and silicon nitride in water increased as the magnitudes of adhesion energies increased and as the virulence of the bacterial strains investigated increased. In the third study, the relationship between the nano-mechanical properties of bacterial cells and surface biopolymers and bacterial virulence was investigated for L. monocytogenes virulent and avirulent strains. Our results indicated that the virulent strains were characterized by more flexible biopolymers, longer and denser biopolymer brushes and thus more rigid bacterial cells compared to the avirulent strains. Our last study investigated in details the means by which a pathogenic L. monocytogenes strain survives under chemical stress. We as well investigated the relationship between the bacterial adhesion energies quantified for individual L. monocytogenes cells and the adhesion energies quantified for lawns of L. monocytogenes cells under chemical stress. Our results indicated that L. monocytogenes cells adapt well in all pH conditions investigated (pH 5 to pH 9). Contact angle measurements on lawns of L. monocytogenes cells indicated that the bacterial surface was always hydrophilic irrespective of the pH conditions of growth. Finally, the femto-Joule scale interaction energies of L. monocytogenes calculated from AFM measurement scaled linearly with macroscale surface adhesion energies estimated using the thermodynamic-based approach.
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Details
- Title
- PROBING THE MOLECULAR MECHANISMS OF PATHOGENIC AND NON-PATHOGENIC LISTERIA ADHERENCE THROUGH SURFACE BIOPOLYMERS
- Creators
- Bong-Jae Park
- Contributors
- Nehal I Abu-Lail (Advisor)Richard L Zollars (Committee Member)Haluk Beyenal (Committee Member)Wenji Dong (Committee Member)Laurence Brewer (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Chemical Engineering and Bioengineering, School of
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Number of pages
- 291
- Identifiers
- 99900581662301842
- Language
- English
- Resource Type
- Dissertation