Examining Initial Bacterial Adhesion: Oriented Adhesion and Surface Nanodomains
Open Access
- Author:
- Jones, Joseph Francis
- Graduate Program:
- Chemical Engineering
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- October 06, 2005
- Committee Members:
- Darrell Velegol, Committee Chair/Co-Chair
Seong H Kim, Committee Member
Costas D Maranas, Committee Member
John Michael Regan, Committee Member
Andrew Zydney, Committee Member - Keywords:
- bacterial adhesion
bacterial polarity
laser trap
orientation
adhesion
nanodomain - Abstract:
- Initial bacteria adhesion is the first step in the process of biofilm formation, affecting areas as diverse as infection on biomedical implants to the efficiency of bioremediation strategies to industrial biofouling. Escherichia coli were studied to better understand the orientations, time scales, and length scales of initial adhesion. The E. coli K-12 D21 strain was found to initially adhere via a single end of the rod-shaped cells. This adhesion was found to be instantaneous (< 1 second). By comparison with strains of varying lipopolysaccharride (LPS) layer, the LPS molecules were determined not to be the adhesive molecules. As well, with Brownian dynamics simulations, the end-on adhesion found for D21 could not be explained simply by geometric effects. The existence of bacterial polarity, a localization of molecules at the pole of the cell, was supported with surface charge nonuniformity measurements. The extent of adhesion within a population of D21 cells was found to be 15.9 +- 3.4% via the end, and the development of a single adhesive end was connected to the cell division process. The surface of D21 was hypothesized to be more complex than a localization of molecules at a single end with smaller nanodomains distributed across the cell body. The threshold area of the adhesive end and the smaller nanodomains was estimated as 0.016 microns squared. Though E. coli D21 predominantly adhere end-on via a single end, the surface characteristics of D21 were shown to change significantly with differing growth conditions. The end-on adhesion effect did not readily extend to two Burkholderia cepacia strains, but the paradigm of examining the bacterial surface as discrete nanodomains when discussing adhesion remains supported.