Inactivation of E. coli by high-intensity pulsed electromagnetic field with a change in the intracellular Ca²⁺ concentration

Abstract

This study investigated the inactivation effect of high-intensity pulsed electromagnetic field (PEF) on Escherichia coli ATCC 8099 and explored the primary mechanism of PEF on the microbe. After PEF treatment, the survival rate (SR) of E. coli 8099 remarkably decreased. When treated by 2.5 T intensity PEF at 30 °C for 20 pulses, 18.3% SR of E. coli cultures was observed. The experimental results also indicated that E. coli 8099 in the log phase was more sensitive to PEF treatment and a change in the PEF treatment temperature, intensity or pulse number significantly affected the inactivation of E. coli 8099. The inactivation effect of PEF treatment was found to be related to the change of the intracellular Ca²⁺ concentration ([Ca²⁺]_i) of E. coli 8099; i.e. an increase in [Ca²⁺]_i was a possible factor in the inactivation of E. coli cells by PEF treatment.

Keywords:

• high-intensity pulsed electromagnetic field
• Escherichia coli
• inactivation
• intracellular Ca²⁺ concentration