Comparative analysis of fatty acid profiles in listeria monocytogenes isolates from food processing environments grown at 37 ºC and 10 ºC: exploring potential persistence markers

Introduction: Listeria monocytogenes, the causative agent of listeriosis, is a major foodborne pathogen. It is a ubiquitous, facultative anaerobic, gram-positive bacterium. Listeriosis can be a severe illness particularly affecting vulnerable groups: the elderly, immunocompromised individuals, pregnant women and neonates. Listeria monocytogenes exhibits remarkable adaptability to diverse and challenging environments, demonstrating an exceptional capacity to thrive in conditions such as refrigeration temperatures or high salt concentrations or other factors found in food processing environments (FPE). This resilience is a key factor in its ability to persist within food processing facilities and proliferate in various food products. Only certain strains are routinely isolated from these FPEs (persistent strains) while others are isolated sporadically (non-persistent strains). Objectives: The aim of this study was to identify specific membrane fatty acids that could function as persistence markers within a collection of L. monocytogenes isolates from the GenoPhenoTraits4Persistence project culture collection. These markers may help distinguish between persistent (P) and non-persistent (NP) strains in the future. Conclusions: The results revealed the presence of key branched-chain fatty acids (iso-C15 and iso-C17), which are associated with the ability of L. monocytogenes to resist environmental stresses, particularly temperature fluctuations. Additionally, ΔC19 was detected in strains grown at low temperatures. This fatty acid is responsible for the adaption of membrane fluidity in response to environmental stress. These findings provide valuable insights into the lipid composition of L. monocytogenes and highlight potential markers of tolerance to adverse conditions (low temperature). These markers will be further investigated to understand whether they play a role in persistence, providing a deeper understanding of the mechanisms underlying the bacterium's ability to adapt and survive in food processing environments.