Influence of a 7 T magnetic field on growth, biomineralization, and denitrification metabolism in Magnetospirillum gryphiswaldense MSR-1.

Abstract

High magnetic fields represent an extreme physical condition with growing applications in advanced materials and magnetic resonance technologies. However, the physiological and molecular responses of organisms under such conditions remain poorly characterized. Understanding these responses is essential for elucidating magnetobiological mechanisms and enabling biomedical and engineering innovations. Owing to their intrinsic magnetic sensitivity and well-characterized metabolic pathways, magnetotactic bacteria (MTB) offer an ideal model for investigating biological responses to high magnetic fields. Here, we systematically investigated the impact of a steady-state 7 Tesla (7 T) magnetic field on the growth, magnetosome biomineralization, and nitrogen metabolism of the MTB strain Magnetospirillum gryphiswaldense strain MSR-1 (MSR-1). Exposure to the 7 T magnetic field significantly enhanced bacterial proliferation and increased magnetosome number, without altering the average size of individual magnetosome crystals. Transcriptomic analysis demonstrated upregulation of genes encoding the key denitrification enzymes, indicating a pivotal role for nitrogen metabolism in MSR-1 adaptation to the 7 T high magnetic field stress. These transcriptomic results were further supported by proton transfer reaction-mass spectrometry, which confirmed the enhanced denitrification activity under 7 T magnetic field by measuring the intermediate NO and N₂O gas production. Collectively, our findings provide new insights into the biological effects of high magnetic field on MTB and identify nitrogen metabolism as a key mechanism for MTB adaptation to extreme magnetic environments. These work advances our understanding of microbial magnetic responses and expands the knowledge of magnetobiology.

Importance: The physiological impacts of high magnetic fields on microorganisms remain poorly understood. Here, we establish a stable 7 Tesla static magnetic field platform to investigate how Magnetospirillum gryphiswaldense MSR-1 responds to extreme magnetic environments. We show that high-field exposure accelerates bacterial growth and increases magnetosome production, coinciding with transcriptional upregulation of key denitrification genes. Using transcriptomics and proton transfer reaction-mass spectrometry, we uncover a metabolic shift toward enhanced redox regulation, suggesting that denitrification plays a central role in magnetic field adaptation. These findings uncover a previously underappreciated connection between magnetic field sensing and metabolic control, providing new insights into how prokaryotes modulate redox homeostasis in extreme environments.