Curcumin-Mediated Sono-Photodynamic Treatment Inactivates Listeria monocytogenes via ROS-Induced Physical Disruption and Oxidative Damage

Sono-photodynamic sterilization technology (SPDT) has become a promising non-thermal food sterilization technique because of its high penetrating power and outstanding microbicidal effects. In this study, Listeria monocytogenes (LMO) was effectively inactivated using curcumin as the sono-photosensitizer activated by ultrasound and blue LED LIGHT. The SPDT treatment at optimized conditions yielded a 4-log reduction in LMO CFU. The Reactive Oxygen Species (ROS) production in LMO upon SPDT treatment was subsequently investigated. The results demonstrated SPDT treatment-induced excessive ROS generation led to Bacterial cell deformation and membrane rupture, as revealed by the scanning electron microscope (SEM) and cytoplasmic material leakage. Moreover, Agarose gel electrophoresis and SDS-PAGE further revealed that SPDT also triggered Bacterial genomic DNA cleavage and protein degradation in LMO, thus inducing Bacterial apoptosis-like events, such as membrane depolarization.