Evaluation of the extremely low-frequency electromagnetic field (ELF-EMF) on the growth of bacteria Escherichia coli

The goal of this work was to evaluate the biological effect of the extremely low frequencies (ELFs). We started by evaluating the effect of frequencies with the anti-bacterial functions listed in the Rife frequency database on the growth of Escherichia coli. Among the 11 sets of frequencies tested, we found that only 1 set comprising frequencies below 100 Hz showed a significant effect on the growth of E. coli, and it was an enhancement effect instead of an inhibition on the growth. We further tested various sets of frequencies without anti-bacterial functions but comprising frequencies below 100 Hz, and they all exhibited a significant promoting effect on the growth of E. coli when exposed to the irradiation for 1 h. We further evaluated the effect of the ELFon the growth of E. coli by scanning from 0 to 100 Hz. The results showed that the growth rate was noticeably enhanced for the group exposed to the irradiation at the range of 0-100 Hz, with the range of 40-60 Hz being the most effective. In addition, the effect was time dependent, demonstrated by a significant increase of the growth rate observed after exposure of 1 h but a slight decrease after exposure of 16 h. The results of this study provided robust data on the biological effect of ELF on the growth of E. coli, an important group of human microbiota, which has critical implication on the safety risk of these frequencies on human health.