Nanoscale cell wall deformation impacts long-range bacterial adhesion forces on surfaces

Area of Science:

• Microbiology
• Biophysics
• Materials Science

Background:

• Bacterial adhesion to surfaces is critical for survival and biofilm formation.
• Adhesion involves complex short- and long-range forces.
• Understanding these forces is key to controlling bacterial colonization.

Purpose of the Study:

• To develop and apply a novel atomic force microscopy (AFM)-based method for measuring long-range bacterial adhesion forces.
• To investigate the role of bacterial cell wall deformability in adhesion.
• To quantify the contribution of cell deformation to adhesion forces.

Main Methods:

• Utilized atomic force microscopy (AFM) to measure bacterial adhesion forces under varying loading forces.
• Employed peak force quantitative nanomechanical property mapping to image bacterial cell deformation.
• Compared adhesion forces and cell deformation between wild-type Staphylococcus aureus and a Δpbp4 mutant.

Main Results:

• A new AFM method successfully derived long-range bacterial adhesion forces.
• Deformable Δpbp4 mutants exhibited significantly higher long-range adhesion forces (2-3 times) compared to wild-type strains.
• Cell wall deformation (100-200 nm reduction) in mutants correlated with increased Lifshitz-Van der Waals forces, matching theoretical calculations.

Conclusions:

• Bacterial cell wall deformation is a crucial, previously underestimated factor influencing long-range adhesion forces.
• The developed AFM method provides a robust way to quantify these forces and the impact of deformation.
• Adhesion forces are determined by both surface properties and cell wall deformability, impacting biofilm formation.