Lethal effects of high-voltage pulses on E. coli K12

Area of Science:

• Microbiology
• Biophysics
• Electrochemistry

Background:

• Bacterial inactivation is crucial for public health and industrial processes.
• High-voltage electrical discharges are explored as a non-thermal pasteurization method.
• Understanding the mechanisms of electrical inactivation is essential for optimizing treatment efficacy.

Purpose of the Study:

• To investigate the lethal effects of high-voltage capacitor discharges on Escherichia coli K12 suspensions.
• To determine the influence of varying electrolytes and cell concentrations on bacterial inactivation.
• To elucidate the contributing factors to the bactericidal action, including electric fields and chemical agents.

Main Methods:

• Exposure of E. coli K12 suspensions to high-voltage capacitor discharges.
• Varying electrolyte compositions and concentrations in the bacterial suspensions.
• Adjusting the initial cell density of the bacterial cultures.
• Quantifying bacterial survival rates post-treatment.

Main Results:

• A reduction of over 99.9% in viable E. coli K12 cells was achieved, dependent on applied voltage.
• Electrolytically produced chlorine, in the presence of chloride, acted as an additional bactericidal agent.
• Bacterial survival rates were influenced by both the applied voltage and the initial cell concentration.
• The primary bactericidal mechanism is attributed to direct effects of high electric fields.

Conclusions:

• High-voltage capacitor discharges are a potent method for inactivating E. coli K12.
• The presence of chloride enhances inactivation through the generation of toxic chlorine species.
• Cell concentration plays a significant role in the effectiveness of electrical bacterial inactivation.
• Further research can optimize electrical treatment parameters for effective microbial control.