Differences between clinical and food isolates of Listeria monocytogenes in transcription levels of inlA, hly, lmo1634, lmo1847, sigB, and prfA genes in shrimp broth

Listeriosis, an important illness with a high mortality rate (up to 30%), is caused by Listeria monocytogenes. Nowadays, there are several reports that display the prevalence of L. monocytogenes in fisheries products. Therefore, it is important to investigate and control the expression of virulence genes and adhesion-related genes in different strains of this bacterium in foodstuffs. In this study, the expression levels of inlA, hly, lmo1634, lmo1847, sigB, and prfA genes in two isolates (food and clinical) were investigated under the influence of NaCl and lime juice in the shrimp broth. The results of the independent t-test for the prfA gene demonstrated that the expression level in the treatments of clinical strain was significantly higher than the food strain (p<0.05). Similarly, the average expression of both adhesion genes (lmo1847 and lmo1634) and stress gene (sigB) in the studied treatments for the clinical strain was significantly higher than the food strain. In both strains, the role of lime juice in increasing the expression of virulence and adhesion genes was significantly higher than in NaCl treatments (p<0.05). Overall, it can be stated that the transcription level of virulence- and adhesion-related genes upon exposure to preservatives may be different in the various L. monocytogenes isolates.