Dynamic Magnetic Field Modulation of Photosynthetic Redox Responses Promotes Biomass Accumulation in Cyanobacteria

Abstract Cyanobacteria play an increasingly important role in wastewater bioremediation and carbon recovery, owing to their ability to assimilate nutrients while converting CO2 into biomass and value-added products. However, despite the exceptionally high quantum efficiency of the photosystems, the overall conversion of absorbed solar energy into biomass remains constrained by multiple photosynthetic and downstream energy-conversion processes. To address this limitation, magnetic field exposure was investigated as a green, noninvasive intensification strategy for promoting cyanobacterial growth and photosynthetic physiological responses of Synechococcus sp. PCC 11901. Comparative analyses revealed that 20 Hz rotating dynamic magnetic fields (DMFs) significantly outperformed static magnetic fields in promoting biomass accumulation. Under DMF exposure, the doubling time was shortened by 16.12% compared to the control group, with increased chlorophyll a concentration and cell density supporting enhanced growth. Further analyses revealed increased phycobiliprotein fluorescence, altered PC:APC fluorescence ratios, changes in cellular NADPH/NADP+ redox balance, and exploratory transcriptional changes in photosynthesis- and energy-metabolism-related genes. To explore a possible physical basis for the distinct effects of dynamic versus static magnetic fields, spin-dynamics simulations using the Spinach package were performed as a hypothesis-generating framework. The simulations suggested, within a simplified Mn-cluster/TyrZ radical-pair model, that time-varying magnetic fields could alter singlet-state population dynamics more strongly than static fields. Together, these results indicate that DMF exposure is associated with changes in light-harvesting components and cellular redox status, while the spin-dynamics simulations suggest a possible contribution from spin-dependent processes to these physiological responses. These findings highlight the engineering potential of DMF-based physical regulation for cyanobacterial biomass accumulation and sustainable phototrophic bioprocesses.