Electric field effects on bacteria and yeast cells

Area of Science:

• Microbiology
• Biophysics

Background:

• Electric pulses are increasingly explored for microbial inactivation.
• Understanding the precise mechanisms of electric pulse lethality is crucial for optimizing applications.

Purpose of the Study:

• To investigate the lethal effects of electric pulses on Gram-negative bacteria, Gram-positive bacteria, and yeast.
• To characterize the survival kinetics as a function of electric field strength and treatment time.
• To elucidate the role of physiological properties and growth phases in microbial susceptibility.

Main Methods:

• Comparative studies exposing microbial cultures (Gram-negative bacteria, Gram-positive bacteria, yeast) to electric pulses.
• Quantification of survival rates based on varying electric field strength (E) and treatment time (t).
• Analysis of survival data to identify key parameters governing microbial inactivation kinetics.

Main Results:

• Microbial cells were killed by electric pulses without apparent morphological destruction.
• Survival rates were dependent on electric field strength, treatment time, microbial species, and growth phase.
• Gram-negative bacteria were more sensitive than Gram-positive bacteria and yeasts at low pulse numbers.
• High pulse numbers resulted in survival rates below 1% for all tested microorganisms.
• Logarithmic growth phase cells exhibited higher susceptibility compared to stationary phase cells.

Conclusions:

• Electric pulse treatment is an effective method for microbial inactivation.
• Three explicit parameters sufficiently explain the kinetics of electric pulse-induced microbial death.
• The findings support the hypothesis of electric-induced selective damage to inner cell membranes.
• Microbial species and physiological state significantly influence susceptibility to electric pulse treatment.