Comparative genomics and phenotypes of Listeria monocytogenes isolated from enoki mushrooms in South Korea and China

Listeria monocytogenes is a gram-positive and facultatively anaerobic foodborne pathogen causing listeriosis. The detection of L. monocytogenes in enoki mushrooms sourced from South Korea and China is particularly critical, given their confirmed implication in recent serious listeriosis outbreaks across the global food supply chain. This study investigates the prevalence, genetic diversity, and phenotypical characteristics of L. monocytogenes in enoki mushrooms from South Korea and China. Out of 129 samples, 24 (18.6%) tested positive, with contamination rates of 17.5% in Korean mushrooms and 19.7% in Chinese mushrooms. Whole-genome sequencing, cgMLST, and pan-genome analyses resolved lineage and sequence-type distributions, revealing predominant serogroup 1/2a (83.3%) and lineage II (90.9%). The pan-genomic assessment of L. monocytogenes strains originating from diverse geographical locations indicated the presence of open genomes, which establishes a strong genetic underpinning for adaptation to varied environments. These strains carrying a multitude of virulence genes that significantly contribute to their heightened pathogenic potential. The phylogenetic tree further demonstrated that these highly related Korean and Chinese isolates were intricately intermingled with outbreak-related strains from the USA, Canada, and Europe, confirming a minimal core-genome genetic distance across the global supply chain. This highly homogenous clone, which was ultimately traced back to enoki mushrooms in South Korea and China, suggests that the globalization of the food trade is the primary driver of its rapid, international dissemination.