Resistance-Nodulation-Cell Division (RND) Transporter AcrD Confers Resistance to Egg White in Serovar Enteritidis.

The excellent survival ability of serovar Enteritidis (. Enteritidis) in egg white leads to outbreaks of salmonellosis frequently associated with eggs and egg products. Our previous proteomic study showed that the expression of multidrug efflux RND transporter AcrD in . Enteritidis was significantly up-regulated (4.06-fold) in response to an egg white environment. In this study, the potential role of AcrD in the resistance of . Enteritidis to egg white was explored by gene deletion, survival ability test, morphological observation, Caco-2 cell adhesion and invasion. It was found that deletion of had no apparent effect on the growth of . Enteritidis in Luria-Bertani (LB) broth but resulted in a significant ( < 0.05) decrease in resistance of . Enteritidis to egg white and a small number of cell lysis. Compared to the wild type, a 2-log population reduction was noticed in the mutant with different initial concentrations after incubation with egg white for 3 days. Furthermore, no significant difference ( > 0.05) in the adhesion and invasion was found between the wild type and mutant in LB broth and egg white, but the invasion ability of the mutant in egg white was significantly ( < 0.05) lower than that in LB broth. This indicates that is involved in virulence in . Taken together, these results reveal the importance of AcrD on the resistance of . Enteritidis to egg white.