Relative Comparison of the Static Magnetic Field and Oscillating Magnetic Field Effects on Gram-Negative and Gram-Positive Bacteria via Evaluating Oxidative Stress and DNA Fragmentation

Abstract

The effects of static magnetic field (SMF) and oscillating magnetic field (OMF) on oxidative stress responses and DNA fragmentation were investigated in Staphylococcus aureus and Escherichia coli. Bacterial cultures were exposed to magnetic field intensities ranging from 2 to 16 mT at 50 Hz for 8 h. Exposure to both SMF and OMF caused intensity-dependent decreases in optical density, indicating growth inhibition. In parallel, nitric oxide and superoxide anion radical levels, as well as the activities of catalase and superoxide dismutase, increased significantly in a field-strength–dependent manner. Glutathione disulfide levels were enhanced while reduced glutathione values decreased, reflecting a redox imbalance. Moreover, malondialdehyde and DNA fragmentation levels were markedly elevated, confirming oxidative and genotoxic stress. Comparative analysis revealed that E. coli exhibited more pronounced responses than S. aureus, with significant effects emerging above approximately 6–8 mT for OMF and 8–10 mT for SMF exposure. Overall, these findings demonstrate that both OMF and SMF can induce oxidative stress and DNA damage in bacterial cells, with OMF producing stronger effects. The results highlight the differential susceptibility of Gram-positive and Gram-negative bacteria to electromagnetic exposure and suggest potential implications for non-antibiotic antimicrobial strategies based on magnetic fields. Bioelectromagnetics. 00:00–00, 2026. © 2026 © 2026 Bioelectromagnetics Society.