Qin Xiaojie, Liu Yanhong, Shi Xianming
School of Health Science and Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China.
Molecular Characterization of Foodborne Pathogens Research Unit, Eastern Regional Research Center, Agricultural Research Service, United States Department of Agriculture, Wyndmoor, PA 19038, USA.
Foods. 2021 Dec 30;11(1):90. doi: 10.3390/foods11010090.
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.
肠炎血清型（肠炎沙门氏菌）在蛋清中出色的生存能力导致经常与蛋类及蛋制品相关的沙门氏菌病暴发。我们之前的蛋白质组学研究表明，肠炎沙门氏菌中多药外排RND转运蛋白AcrD的表达在蛋清环境下显著上调（4.06倍）。在本研究中，通过基因缺失、生存能力测试、形态学观察、Caco-2细胞黏附及侵袭实验，探究了AcrD在肠炎沙门氏菌对蛋清抗性中的潜在作用。结果发现，缺失该基因对肠炎沙门氏菌在Luria-Bertani（LB）肉汤中的生长无明显影响，但导致肠炎沙门氏菌对蛋清的抗性显著降低（P<0.05）且有少量细胞裂解。与野生型相比，用蛋清培养3天后，不同初始浓度的该突变体的菌量减少了2个对数级。此外，在LB肉汤和蛋清中，野生型和该突变体在黏附及侵袭方面未发现显著差异（P>0.05），但该突变体在蛋清中的侵袭能力显著低于（P<0.05）其在LB肉汤中的侵袭能力。这表明该基因参与了肠炎沙门氏菌的毒力作用。综上所述，这些结果揭示了AcrD对肠炎沙门氏菌抵抗蛋清的重要性。
