Decoding adaptive protein networks in Listeria monocytogenes: Proteomic insights for food safety and control

Listeria monocytogenes is a key pathogen in the ready-to-eat (RTE) food production chain, particularly in meat products, where its ability to persist and grow under refrigeration poses major challenges for food safety. Its control is complicated by the pathogen’s frequent occurrence in food-associated environments, persistence on processing surfaces, and remarkable tolerance to multiple stress conditions [1]. This study compared the proteomic profiles of two L. monocytogenes strains: a hypovirulent strain isolated from food (F) and a hypervirulent clinical strain (H), both derived from the reference strain ATCC BAA-679/EGD-e obtained from the Italian National Reference Laboratory for L. monocytogenes (IZSAM, Teramo, Italy). Cultures were grown at 37°C to mimic host conditions, and proteins were analyzed by LC-MS/MS following digestion by the filter-aided sample preparation (FASP) method. A total of 954 proteins were identified, including 642 predicted to be immunogenic using Vaxijen version 2.0 [2]. Among these, 128 were unique to the food strain, 27 to the clinical strain, and 487 were shared. Functional enrichment analysis revealed that proteins specific to the food strain were mainly involved in motility, chemotaxis, flagellar assembly, and secretion, reflecting environmental adaptability and persistence in food matrices [3]. Conversely, the clinical strain expressed proteins associated with the glutamate-dependent acid resistance (GDAR) system and phage-related functions, supporting its enhanced survival and virulence within the host. These findings demonstrate targeted proteomic remodeling in response to environmental cues, illustrating the bacterium’s transition from foodborne persistence to host adaptation. The identification of immunogenic and strain-specific proteins provides molecular markers for improved diagnostics, therapeutic targeting, and food safety strategies, contributing to more effective control of L. monocytogenes in RTE foods.