Metabolic-State-Dependent Magnetic Field Effects on Endogenous Flavin Autofluorescence in Escherichia coli

Endogenous autofluorescence in Escherichia coli changes by more than 10% under a 25 mT magnetic field in specific physiological and excitation conditions.

• Why it matters: The work addresses how to identify endogenous biomolecules with large intracellular magnetic field effects and how such effects could enable label-free readouts of cellular metabolic state.
• What they did: Using fluorescence spectroscopy, the authors analyze magnetically sensitive signals and find spectral features consistent with a flavin origin, including a slight blue shift versus free flavin. They also show the response is suppressed by carbon-source supplementation and exhibits negative, saturating field dependence.
• The result: The ensemble-averaged effect exceeding 10% in total autofluorescence implies a larger intrinsic effect within a magnetically sensitive flavin subpopulation, consistent with a radical-pair mechanism and triplet-born radical-pair reaction.