Inactivation effect and mechanism of dielectric barrier discharge plasma on B. cereus spores: Insights into reactive species-mediated structural damages

This work elucidated the inactivation efficacy and possible mechanisms of B . cereus spores by dielectric barrier discharge (DBD) plasma. DBD plasma induced time- and power-dependent inactivation of B . cereus spores, achieving a maximum reduction exceeding 7.48-log at 30.72 W for 100 s. Scanning electron microscopy and transmission electron microscopy revealed severe morphological and structural damage in DBD plasma-treated spores, including surface erosion, cortex disintegration, core dispersion, and exosporium degradation. DBD plasma compromised the membrane integrity of B . cereus spores, thereby resulting in substantial leakage of intracellular components (such as nucleic acids and proteins). DBD plasma also reduced the spores' ability to retain Ca 2+ -dipicolinic acid, a critical component involved in spore resistance and stability. Additionally, DBD plasma significantly reduced the surface hydrophobicity and absolute zeta potential, affecting key surface properties of B. cereus spores. The intracellular reactive oxygen species (ROS) level increased by 211% following 100 s of DBD plasma treatment. Furthermore, antioxidants (glutathione and N-acetylcysteine) effectively attenuated the sporicidal efficacy of DBD plasma, indicating the important role of reactive species in spore inactivation. This study provides a theoretical foundation for the potential of DBD plasma as an attractive alternative to traditional spore inactivation methods in the food industry.