Efficient low-temperature inactivation of Listeria monocytogenes in food matrices using a cold-adapted Fe/Mn-MOF nanozyme.

Listeria monocytogenes, a hazardous foodborne pathogen, poses severe threats to public health, particularly under low-temperature and cold-chain conditions. This study developed a cold-adapted nanozyme, iron/manganese-based metal-organic framework (Fe/Mn-MOF), and systematically evaluated its enzyme-like properties and antibacterial performance against L. monocytogenes under low-temperature conditions. The Fe/Mn-MOF was synthesized via a conventional solvothermal method and was discovered to display multifunctional nanozyme behavior, emulating the catalytic activities of oxidase, peroxidase, and superoxide dismutase. Notably, the Fe/Mn-MOF retained high catalytic activity even below freezing. Based on its robust enzyme-like activities, the Fe/Mn-MOF was applied for the inactivation of L. monocytogenes. Quantitative results demonstrated significant bacterial reduction and biofilm inhibition at all tested temperatures compared with temperature-matched controls. The antibacterial mechanism was attributed to the enhanced generation of reactive oxygen species (ROS) through enzyme-mediated catalysis. In addition, the Fe/Mn-MOF depleted intracellular reduced glutathione (GSH) by oxidizing it to glutathione disulfide (GSSG), thereby disrupting the antioxidant defense system of L. monocytogenes. These synergistic effects resulted in biofilm formation inhibition, cell membrane damage, and leakage of intracellular proteins and nucleic acids. Furthermore, the antibacterial efficacy of the Fe/Mn-MOF was validated in a food-model system under low-temperature conditions, demonstrating its potential as a cold-adapted nanozyme for controlling L. monocytogenes in cold-chain food safety applications.