Insights into the gene regulation of Listeria monocytogenes incubated on corn salad

In this work it was investigated by RNA-seq how the colonization of corn salad leaves and the commonly used packaging material polystyrene impacts on the transcriptome of L. monocytogenes NCTC 10887 at 4 °C and 22 °C. The strongest transcriptional differences occurred on corn salad at 4 °C versus polystyrene at 4 °C, yielding 2,629 differentially expressed genes (91.6% of protein-coding genes), indicating a habitat driven shift under cold-chain conditions.

Corn salad promoted regulation of virulence related genes. The prfA gene was upregulated on corn salad compared to polystyrene at both temperatures (log2FC 2.43 at 22 °C and 4.16 at 4 °C), accompanied by increased hly (2.70), inlA (4.46), and inlB (2.10) expression at 4 °C. Stress/proteostasis gene expression was elevated on corn salad, including higher transcripts of clpP (3.34–3.51), clpE (5.58–6.89), and clpB (2.08–3.74), consistent with a stressed yet persistence-prone state on leaf surfaces.