Biochemical and molecular regulatory mechanism of thepgpHgene on biofilm formation inListeria monocytogenes

PgpH gene has an important regulatory role on bacterial physiological activity, but studies on its regulation mechanism on biofilm formation of Listeria monocytogenes are lacking. Our aim was to investigate the effect of pgpH gene deletion on biofilm formation in L. monocytogenes.The ΔpgpH deletion strain of L. monocytogenes LMB 33 426 was constructed by homologous recombination. Deletion of the pgpH gene resulted in a significant reduction in biofilm formation. The swimming ability of the ΔpgpH strain on semisolid plates was unchanged compared to the wild-type strain (WT), and the auto-aggregation capacity of L. monocytogenes was decreased. RNA-seq showed that ΔpgpH resulted in the differential expression of 2357 genes compared to WT. pgpH inactivation resulted in the significant downregulation of the cell wall formation-related genes dltC, dltD, walK, and walR and the flagellar assembly related genes fliG and motB.This study shows that the deletion of pgpH gene regulates biofilm formation and auto-aggregation ability of L. monocytogenes by affecting the expression of flagellar assembly and cell wall related genes. pgpH has a global regulatory effect on biofilm formation in L. monocytogenes.