Alterations of bacterial dielectric characteristics due to pulsed magnetic field exposure

Abstract

The effect of exposure to 0·1 Hz–0·1 kHz pulsed magnetic fields on models of gram-positive and gram-negative bacterial cells was investigated. The possible alterations in the electrical characteristics of dead and alive bacteria cells were monitored by using dielectric spectroscopy. The dielectric dispersions of cells were obtained over the range 42 Hz–8 MHz by measuring their dielectric permittivity and conductivity. The acquired results indicated exposure enhancement and inhibition effects on both bacterial models in different frequency windows. The spectroscopy results for all bacterial cells indicated two sizeable dispersions in low- and high-frequency ranges (so-called α- and β-dispersions) due to different polarization mechanisms. Remarkable variations in the dielectric relaxations were observed due to exposure as a result of possible alterations in the counterion clouds and ionic membrane permeability, plasma and cell wall charge residues. In conclusion, both bacterial models demonstrated considerable response to exposure, resulting in a significant electrochange in the cell membrane/wall structure. Moreover, by performing dielectric spectroscopy, it is possible to distinguish between normal and abnormal cells. It is worth mentioning that the observed results can be achieved when using resonance frequencies outside the range used in the study.