Bacterial growth rates are influenced by cellular characteristics of individual species when immersed in electromagnetic fields

Previous studies have shown that exposure to extremely low-frequency electromagnetic fields (ELF-EMFs) have negative effects on the rate of growth of bacteria. In the present study, two Gram-positive and two Gram-negative species were exposed to six magnetic field conditions in broth cultures. Three variations of the 'Thomas' pulsed frequency-modulated pattern; a strong-static puck magnet upwards of 5000 G in intensity; a pair of these magnets rotating opposite one another at similar to 30 rpm; and finally a strong dynamic magnetic field generator termed the 'Resonator' with an average intensity of 250 mu T were used. Growth rate was discerned by optical density (OD) measurements every hour at 600 nm. ELF-EMF conditions significantly affected the rates of growth of the bacterial cultures, while the two static magnetic field conditions were not statistically significant. Most interestingly, the 'Resonator' dynamic magnetic field increased the rates of growth of three species (Staphylococcus epidermidis, Staphylococcus aureus, and Escherichia coli), while slowing the growth of one (Serratia marcescens). We suggest that these effects are due to individual biophysical characteristics of the bacterial species. (C) 2015 Elsevier GmbH. All rights reserved.