Expression of the hly and inlA genes of Listeria monocytogenesgenes bacteria in viable but non-culturable (VBNC) condition in temperatures of 4 degrees Celsius

Listeria monocytogenes is a gram-positive and foodborne pathogen that is psychrophilic and has the ability to tolerate a high percentage of salt by more than 10%. This bacterium grows in many food products that have a long shelf life. This study was performed to evaluate the expression of genes hly and inlA of Listeria monocytogenes bacteria in the viable but non-culturable (VBNC) condition in temperatures of 4 degrees Celsius.

In this descriptive laboratory study, bacteria in 106 counts in mid log phase were inoculated into BHI Agar rich medium and It was investigated and stored at refrigerated temperature (4 degrees Celsius) until the cultivate was lost. At the end of the 16S rRNA gene, the hly and inlA genes were studied as pathogenic genes of this bacterium. The expression of these genes before and after entering to VBNC state was performed to compare their expression.

Listeria bacteria lost its cultivation ability after 5 months of storage at a refrigerated temperature. The results of the gene expression analysis showed that at the end of the period, the bacterium entered "Viable But non-Culturable" form; also the hly and inlA pathogenic genes were not expressed in riched medium. By adding blood to the rich culture medium of this bacterium, the hemolysin O pathogen gene was re-illuminated.

The results of this study show that the possibility of bacterial entry into VBNC mode occurs at the refrigerator condition, and the expression of its pathogenic genes is affected. Blood and its agents can act as an agent for the induction and clarification of the hly gene. Therefore, it is necessary to review the microbial quality control of fishery products.