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Heterogeneity in bacterial surface polysaccharides, probed on a single-molecule basis
Terri A Camesano1, Nehal I Abu-Lail
1Department of Chemical Engineering, Worcester Polytechnic Institute, 100 Institute Road, Worcester, Massachusetts 01609, USA. terric@wpi.edu
Biomacromolecules
|July 9, 2002
Summary
This study reveals significant variability in bacterial surface molecules, even on a single cell. These findings highlight the diverse nature of bacterial biopolymers and their adhesion properties.
Area of Science:
- Microbiology
- Biophysics
- Polymer Science
Background:
- Bacterial surface macromolecules play crucial roles in cell adhesion and interaction.
- Understanding the heterogeneity of these molecules is essential for accurate modeling of bacterial behavior.
Purpose of the Study:
- To investigate the heterogeneity of individual bacterial surface macromolecules using single-molecule force spectroscopy.
- To quantify variations in biopolymer length, adhesion affinity, and flexibility on Pseudomonas putida KT2442.
Main Methods:
- Utilized atomic force microscopy (AFM) for single-molecule force spectroscopy (SMFS) to probe bacterial surface biopolymers.
- Applied the freely jointed chain (FJC) model to analyze force-extension curves and determine polymer properties.
- Employed size-exclusion chromatography to confirm polymer size distribution.
Main Results:
- Observed significant heterogeneity in biopolymer lengths (tens to hundreds of nanometers) and adhesion affinities (0 to >1 nN) on individual bacteria.
- Determined a range of segment lengths (stiffnesses) for biopolymers, indicating heterogeneity beyond molecular weight.
- Found biopolymers to be flexible in various salt concentrations, with slight extension differences between water and salt solutions.
Conclusions:
- Bacterial surface biopolymer properties exhibit greater heterogeneity than previously assumed, both within a single cell and across a population.
- This heterogeneity in length, stiffness, and adhesion should be considered in models of bacterial adhesion.
- Adhesion properties were largely independent of salt concentration due to low charge and overwhelming heterogeneity.