Comparative studies of bacteria with an atomic force microscopy operating in different modes

Area of Science:

• Microbiology
• Biophysics
• Materials Science

Background:

• Escherichia coli (E. coli) is a model organism for bacterial studies.
• Atomic Force Microscopy (AFM) allows high-resolution imaging of biological surfaces.
• Understanding bacterial cell surface properties is crucial for various applications.

Purpose of the Study:

• To investigate the surface morphology of two E. coli strains (JM109 and K12 J62) using AFM.
• To analyze the impact of environmental conditions on bacterial cell structure.
• To evaluate the effect of lysozyme on E. coli cell surface integrity.

Main Methods:

• Imaging of E. coli strains JM109 and K12 J62 using Atomic Force Microscopy (AFM).
• Comparison of different AFM modes: contact, tapping, and MAC (Maneuvering Atomic Contact).
• In-situ imaging of bacterial cells in culture medium to observe lysozyme treatment effects.

Main Results:

• Significant differences in surface morphology were observed between the two E. coli strains.
• Rehydration led to loss of topographic features and increased cell dimensions (lateral and vertical) for both strains.
• Lysozyme treatment in culture medium caused loss of surface rigidity and dramatic changes in bacterial cell shape.

Conclusions:

• AFM is effective in differentiating bacterial strains based on surface morphology.
• Environmental factors significantly influence E. coli cell structure and integrity.
• Lysozyme degrades the E. coli cell surface, leading to morphological alterations.