Escherichia coli Growth Changes by the Mediated Effects After Low-Intensity Electromagnetic Irradiation of Extremely High Frequencies

Abstract

Water is the major constituent of environmental medium and biological systems. The effects occurring in water as a result of low-intensity electromagnetic irradiation (EMI) in extremely high frequencies are supposed to be the primary mechanism to create conditions for biological responses. The EMI effects on Escherichia coli, after irradiation of their suspension, are most probably water-mediated. Indirect effects of EMI at 51.8, 53, 70.6, and 73 GHz frequencies on bacteria, through water, assay buffer (Tris-phosphate buffer with inorganic salts at low or moderate concentrations), or peptone growth medium were studied. The mediated effects of 70.6 and 73 GHz irradiated water, assay buffer, and growth medium on E. coli growth characteristics were insignificant. But the results were different for 51.8 and 53 GHz. EMI mediated effects on bacterial growth were clearly demonstrated. The effects were more strongly expressed with 53 GHz. Moreover, it was shown that 70.6 and 73 GHz similarly suppressed the cell growth after direct irradiation of E. coli in water or on solid medium. Interestingly, for 51.8 and 53 GHz the bacterial growth decreases after suspension irradiation was less, compared to the direct irradiation of bacteria on solid medium. Especially, it was also more expressed in case of 53 GHz. Also with electron microscopy, EMI-induced bacterial cell sizes and structure different changes were detected. In addition, the distinguished changes in surface tension, oxidation-reduction potential and pH of water, assay buffer, growth medium, and bacterial suspension were determined. They depended on EMI frequency used. The differences could be associated with the partial absorbance of EMI energy by the surrounding medium, which depends on a specific frequency. The results are crucial to understand biophysical mechanisms of EMI effects on bacteria.

The distinguishing effects of low-intensity electromagnetic radiation of different extremely high frequencies on Enterococcus hirae : growth rate inhibition and scanning electron microscopy analysis

“…This could be due to temporary alterations in cell morphology by the EMF at 51·8 GHz, as shown with E. coli (Torgomyan et al . ). It is likely to the mediated effects of EMF at these frequencies on E. coli, when the difference in the effects between 51·8 GHz and 53 GHz is observed (Torgomyan et al .…”

“…; Torgomyan et al . ) and others, especially lactic acid bacteria (Soghomonyan and Trchounian ) at different frequencies (Soghomonyan et al . ).…”

“…; Torgomyan et al . , ) and alterations in E. hirae and E. coli cell plasma membrane bioenergetic characteristics, ion transport and enzymatic properties (Trchounian et al . ; Torgomyan et al .…”

“…; Torgomyan et al . , ). But these effects were more strongly expressed in E. hirae, than in E. coli (Torgomyan et al .…”

Molecular Mechanisms Contributing to the Growth and Physiology of an Extremophile Cultured with Dielectric Heating

“…A slightly different cell wall response (an increase in general permeability with no thickening) to microwave exposure (2.45 GHz) was observed in a strain of yeast with microwave exposures up to 90 s, but the cell walls were destroyed if the exposure was longer than 120 s, since the sample heating was not controlled (8). Lowenergy high-frequency (51 to 73 GHz) exposure to growing Escherichia coli cells results in an elongation of cells, overall decrease in growth rate (37), and an increase in cell permeability at low frequency (2.45 GHz) (38) and high frequencies (51 to 73 GHz) (39). An increase in cell permeability was also observed in the Grampositive bacteria Planococcus maritimus, Staphylococcus aureus, and Staphylococcus epidermidis exposed to 18 GHz low-energy microwave radiation, with no subsequent change in cell morphology (40).…”