Atomic force microscopy of mechanically trapped bacterial cells.

Area of Science:

• Microbiology
• Biophysics
• Materials Science

Background:

• Bacterial immobilization is crucial for various applications.
• Mechanical trapping is a common method for immobilizing bacterial cells.
• Extracellular polymeric substances (EPS) can influence bacterial behavior and surface interactions.

Purpose of the Study:

• To investigate the impact of mechanical filtration on bacterial cell structure and membrane.
• To analyze the behavior of extracellular polymeric substances (EPS) during immobilization.
• To assess how immobilization affects atomic force microscopy (AFM) measurements.

Main Methods:

• Mechanical filtration for bacterial cell immobilization.
• Atomic force microscopy (AFM) for analyzing cell surface and structure.
• Use of Staphylococcus epidermidis strains with visible EPS for testing.

Main Results:

• Mechanical immobilization caused significant structural and mechanical deformation of bacterial cell membranes.
• The EPS layer showed potential for movement and accumulation during filtration.
• Deformations may lead to altered AFM force curve parameters and distorted adhesion force measurements.

Conclusions:

• Mechanical filtration can introduce artifacts in bacterial cell analysis.
• EPS layer dynamics during filtration can bias AFM measurements, especially for small cells.
• Careful consideration of immobilization protocols is needed for accurate micro/nano-mechanical testing of bacteria.