Inactivation mechanisms of Acinetobacter haemolyticus subjected to varying duration of pulsed light treatment

Acinetobacter is a prevalent spoilage organism in chilled meat. The pulsed light, a novel non-thermal sterilization method, has been identified as an effective strategy for microbial reduction. However, the underlying inactivation mechanisms of pulsed light remain inadequately understood. This study aimed to elucidate the inactivation mechanisms of Acinetobacter haemolyticus F-2 isolated from chilled chicken subjected to varying duration of pulsed light treatment. The findings indicated that an increase in treatment duration corresponded with a heightened degree of cell membrane damage, resulting in significant leakage of intracellular macromolecules, including proteins and nucleic acids. Transmission electron microscopy (TEM) revealed pronounced wrinkling of the Acinetobacter haemolyticus F-2 cell periphery following pulsed light exposure, with average particle size reductions. Additionally, the permeability of the cell membrane increased, integrity and fluidity are reduced, and depolarization of the membrane potential was noted. Furthermore, the proteins and lipids were also damaged. Flow cytometry results indicated a significant increase in the number of dead Acinetobacter haemolyticus F-2 cells with prolonged treatment duration. In summary, this study elucidates the lethal mechanisms of pulsed light on Acinetobacter haemolyticus F-2, highlighting the roles of cell morphology and membrane in the process. • Increased duration of pulsed light treatment leads to greater mortality rates. • Pulsed light treatment can cause a release of intracellular macromolecules. • Pulsed light treatment resulted in functional damage to the cell membrane. • Pulsed light treatment can change the structure of proteins and lipids.