Abstract: Listeria monocytogenes is a common foodborne pathogen. Cell wall-anchored surface proteins are closely related to the pathogenicity and biofilm formation of the bacterium. The srtA gene is a key factor that mediates the membrane anchoring of surface proteins, and as an important virulence gene of L. monocytogenes it can covalently bind surface proteins to the cell wall by recognizing specific peptide sequences. For a better understanding of the function of srtA and its role in bacterial virulence regulation, we knocked out the srtA gene in L. monocytogenes by homologous recombination in this study, and evaluated the biological properties of the mutant strain. Based on its growth curve examination, we found that the growth rate of the mutant strain was slower than that of the wild-type one. Furthermore, the invasion efficiency of the mutant strain in glioma U251 cells was lower than that of the wild-type one. These results indicate that srtA may play an important role in regulating the invasiveness of L. monocytogenes, which will provide a theoretical basis for further understanding of the regulatory mechanisms of virulence genes in L. monocytogenes and biofilm formation.

Key words: Listeria monocytogenes, srtA gene, homologous recombination, growth curve, invasion