Function Characterization of Endogenous Plasmids in Cronobacter sakazakii and Identification of p-Coumaric Acid as Plasmid-Curing Agent

Virulence traits and antibiotic resistance are frequently provided by genes located on plasmids. However, experimental verification of the functions of these genes is often lacking due to a lack of related experimental technology. In the present study, an integrated suicide vector was used to efficiently and specifically delete a bacterial endogenous plasmid in Cronobacter sakazakii. The pESA3 plasmid was removed from C. sakazakii BAA-894, and we confirmed that this plasmid contributes to the invasion and virulence of this strain. In addition, the pGW1 plasmid was expunged from C. sakazakii GZcsf-1, and we confirmed that this plasmid confers multidrug resistance. We further screened plasmid-curing agents and found that p-coumaric acid had a remarkable effect on the curing of pESA3 and pGW1 at sub-inhibitory concentrations. Our study investigated the contribution of endogenous plasmids pESA3 and pGW1 by constructing plasmid-cured strains using suicide vectors and suggested that p-coumaric acid can be a safe and effective plasmid-curing agent for C. sakazakii.