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

A low-intensity electromagnetic field of extremely high frequency has inhibitory and stimulatory effects on bacteria, including Enterococcus hirae. It was shown that the low-intensity (the incident power density of 006mWcm(-2)) electromagnetic field at the frequencies of 518GHz and 53GHz inhibited E. hirae ATCC 9790 bacterial growth rate; a stronger effect was observed with 53GHz, regardless of exposure duration (05h, 1h or 2h). Scanning electron microscopy analysis of these effects has been done; the cells were of spherical shape. Electromagnetic field at 53GHz, but not 518GHz, changed the cell sizethe diameter was enlarged 13 fold at 53GHz. These results suggest the difference in mechanisms of action on bacteria for electromagnetic fields at 518GHz and 53GHz. Significance and Impact of the StudyA stronger inhibitory effect of low-intensity electromagnetic field on Enterococcus hirae ATCC 9790 bacterial growth rate was observed with 53GHz vs 518GHz, regardless of exposure duration. Scanning electron microscopy analysis showed that almost all irradiated cells in the population have spherical shapes similar to nonirradiated ones, but they have increased diameters in case of irradiated cells at 53GHz, but not 518GHz. The results are novel, showing distinguishing effects of low-intensity electromagnetic field of different frequencies. They could be applied in treatment of food and different products in medicine and veterinary, where E.hirae plays an important role.