Using Impedance Flow Cytometry for Rapid Viability Classification of Heat-Treated Bacteria

Area of Science:

• Microbiology
• Biophysics
• Electrical Engineering

Background:

• Impedance flow cytometry offers rapid cell characterization.
• Bacterial membrane changes due to heat affect electrical properties.
• Understanding these changes is crucial for viability assessment.

Purpose of the Study:

• To investigate how medium conductivity and heat exposure time influence the viability classification of heat-treated E. coli using impedance flow cytometry.
• To correlate theoretical models of membrane perforation with experimental impedance measurements.
• To determine optimal conditions for distinguishing between untreated and heat-treated E. coli.

Main Methods:

• Theoretical modeling of bacterial cell impedance changes post-heat treatment.
• Experimental impedance measurements on E. coli samples.
• Varying suspending medium conductivity and heat exposure durations.
• Analysis of the differential argument of complex electrical current.

Main Results:

• Heat exposure causes bacterial membrane perforation, altering cell impedance.
• This alteration shifts the differential argument of the complex electrical current.
• Increased heat exposure time and decreased medium conductivity enhance classification accuracy.
• Optimal classification was achieved at 0.045 S/m medium conductivity after 30 min heat exposure.

Conclusions:

• Impedance flow cytometry can effectively classify heat-treated E. coli viability.
• Medium conductivity and heat exposure time are critical parameters for accurate classification.
• The study provides a foundation for optimizing impedance flow cytometry for bacterial viability assessment.