A microscopic method to visualize Escherichia coli interaction with beef muscle

Area of Science:

• Microbiology
• Food Science
• Biotechnology

Background:

• Escherichia coli is a significant foodborne pathogen.
• Visualizing bacterial interactions within food matrices is challenging.
• Enhanced green fluorescent protein (EGFP) offers a non-invasive labeling method.

Purpose of the Study:

• To genetically modify Escherichia coli strains (JM109 and O157:H7) with EGFP.
• To assess the impact of EGFP expression on bacterial growth and surface properties.
• To develop a method for observing EGFP-expressing E. coli interactions within beef muscle using confocal microscopy.

Main Methods:

• Introduction of EGFP into E. coli strains via plasmid.
• Evaluation of bacterial growth kinetics, hydrophobicity, and electrophoretic mobility.
• Modification of microscope slides for thick meat sample viewing.
• Staining beef muscle lipids with Nile Red and proteins with Cy3.
• Utilizing laser scanning confocal microscopy for live imaging.

Main Results:

• EGFP expression did not alter E. coli growth kinetics or surface properties.
• A robust method was established for observing bacterial-food interactions.
• Confocal microscopy allowed visualization of E. coli within the beef muscle microenvironment.

Conclusions:

• EGFP is a suitable marker for tracking E. coli in food systems without affecting bacterial physiology.
• The developed microscopy technique facilitates real-time observation of bacterial-food interactions.
• This approach aids in understanding pathogen behavior in complex food matrices.