Evaluación cuantitativa del riesgo microbiológico de patógenos de transmisión alimentaria de alta relevancia para la salud pública en España: Listeria monocytogenes en cadenas de procesado

Listeria monocytogenes remains an important foodborne pathogen due to its persistence in food-processing environments and its increasing incidence within the EU population. The rising consumption of ready-to-eat (RTE) foods, combined with the pathogen’s biofilm-forming ability and tolerance to stress, underscores the need for effective and sustainable control measures. This Doctoral Thesis integrates microbiological, molecular, and risk analysis approaches to characterise L. monocytogenes behaviour, evaluate novel mitigation strategies, and refine public health risk estimation in RTE fish and meat products. Biopreservation using lactic acid bacteria (LAB) proved to be an efficient and natural intervention against L. monocytogenes during refrigerated storage of cold-smoked rainbow trout. LAB cocktails (Leuconostoc carnosum and Lactococcus lactis subsp. lactis) effectively inhibited pathogen growth, while alternative formulations with Lactobacillus plantarum and Lactobacillus pentosus maintained product sensory quality, supporting the use of LAB as sustainable safety alternative. Complementarily, Argon–Nitrogen Cold Plasma Afterglow (Ar–N2 CPA) have demonstrated significant inactivation of L. monocytogenes biofilms on stainless steel (SS) representing a viable non-thermal sanitation technology. Gene expression analyses of desiccated biofilms revealed strain-dependent regulation of sigB, cspA, cspB, flaA, and pdhA, confirming the active molecular mechanisms underlying environmental persistence. These data, integrated into a quantitative microbial risk assessment (QMRA), showed that contamination from biofilm-detached cells poses a considerably higher public health risk than planktonic cells contamination. Overall, this research advances understanding of L. monocytogenes ecology and supports the implementation of innovative, sustainable, and science-based strategies to enhance food safety in RTE production systems.