Mechanisms of magnetic sensing and regulating extracellular electron transfer of electroactive bacteria under magnetic fields

Electroactive bacteria can display notable plasticity in their response to magnetic field (MF), which prompted bioelectrochemical system as promising candidates for magnetic sensor applications. In this study, we explored the sensing and stimulatory effect of MF on current generation by Geobacter sulfurreducens, and elucidated the related mo-lecular mechanism at the transcriptomic level. MF treatment significantly enhanced electricity generation and overall energy efficiency of G. sulfurreducens by 50 % and 22 %, respectively. The response of current to MFs was instantaneous and reversible. Cyclic voltammetry analysis of the anode biofilm revealed that the redox couples changed from -0.31 to -0.39 V (vs. Ag/AgCl), suggesting that MFs could alter electron transfer related components. Differential gene ex-pression analysis further verified this hypothesis, genes associated with electron transfer were upregulated in G. sulfurreducens under MF treatment relative to the control group, specifically, genes encoding periplasmic c-type cy-tochromes (ppcA and ppcD), outer membrane cytochrome (omcF, omcZ, omcB), pili (pilA-C, pilM, and pilV2), and ribo-some. The enhanced bacterial extracellular electron transfer process was also linked to the overexpression of the NADH dehydrogenase I subunit, the ABC transporter, transcriptional regulation, and ATP synthase. Overall, our findings shed light on the molecular mechanism underlying the effects of magnetic field stimuli on EAB and provide a theoretical basis for its further application in magnetic sensors and other biological system.

Automated summary

Electroactive bacteria such as Geobacter sulfurreducens show plasticity in their response to magnetic fields, making them promising candidates for magnetic sensor applications. This study investigated the effects of magnetic fields on current generation by G. sulfurreducens and identified the molecular mechanism underlying this response at the transcriptomic level. Magnetic field treatment significantly enhanced electricity generation and energy efficiency of G. sulfurreducens. The response of current to magnetic fields was instantaneous and reversible. Differential gene expression analysis revealed upregulation of genes associated with electron transfer in G. sulfurreducens under magnetic field treatment.