Low-intensity Static Magnetic Fields Differentially Modulate the Growth Kinetics of Bacillus amyloliquefaciens and Bacillus Subtilis

Abstract

Optimizing the cultivation of Bacillus species is paramount for the scalable production of microbial bio-inputs. This study investigated the application of low-intensity static magnetic fields (100 and 600 Gauss) as a non-invasive physical stimulus to enhance biomass yield in Bacillus amyloliquefaciens and Bacillus subtilis. Standardized inocula (1 × 105 CFU/mL) were cultivated in Müller-Hinton broth under continuous magnetic exposure for 24 hours, with growth dynamics monitored via optical density (OD400) and analyzed using Student's t-test (α = 0.05). The results revealed species-specific physiological responses: B. amyloliquefaciens exhibited a robust, intensity-dependent proliferation increase, achieving relative yield gains of 57.85% at 100 Gauss and 90.00% at 600 Gauss compared to the unexposed control (p < 0.05). Conversely, B. subtilis showed only marginal, non-significant growth trends (26.47% and 24.70% at 100 and 600 Gauss, respectively; p > 0.05). These findings suggest that static magnetic fields act as physiological modulators, likely by altering membrane ion flux and accelerating metabolic pathways. Magnetic stimulation represents a promising, cost-effective, and non-invasive strategy for optimizing biomass production in industrial biofactory systems.