Abstract：
The transmission of antibiotic resistance genes (ARGs) in pathogenic bacteria affects culture animal health, endangers food safety, and thus gravely threatens public health. However, information about the effect of disinfectants - triclosan (TCS) on ARGs dissemination of bacterial pathogens in aquatic animals is still limited. One Citrobacter freundii (C. freundii) strain harboring tet(X4)-resistant plasmid was isolated from farmed grass carp guts, and subsequently conjugative transfer frequency from C. freundii to Escherichia coli C600 (E. coli C600) was analyzed under different mating time, temperature, and ratio. The effect of different concentrations of TCS (0.02, 0.2, 2, 20, 200 and 2000 μg/L) on the conjugative transfer was detected. The optimum conditions for conjugative transfer were at 37 °C for 8h with mating ratio of 2:1 or 1:1 (C. freundii: E. coli C600). The conjugative transfer frequency was significantly promoted under TCS treatment and reached the maximum value under 2.00 μg/L TCS with 18.39 times that of the control group. Reactive oxygen species (ROS), superoxide dismutase (SOD) and catalase (CAT) activities, cell membrane permeability of C. freundii and E. coli C600 were obviously increased under TCS stress. Scanning electron microscope showed that the cell membrane surface of the conjugative strains was wrinkled and pitted, even broken at 2.00 μg/L TCS, while lysed or even ruptured at 200.00 μg/L TCS. In addition, TCS up-regulated expression levels of oxidative stress genes (katE, hemF, bcp, hemA, katG, ahpF, and ahpC) and cell membrane-related genes (fimC, bamE and ompA) of donor and recipient bacteria. Gene Ontology (GO) enrichment demonstrated significant changes in categories relevant to pilus, porin activity, transmembrane transporter activity, transferase activity, hydrolase activity, material transport and metabolism. Taken together, a tet(X4)-resistant plasmid could horizontal transmission among different pathogens, while TCS can promote the propagation of the resistant plasmid.
摘要：
病原菌中抗生素抗性基因(ARGs)的传播影响养殖动物健康,危害食品安全,从而严重威胁公众健康。然而,关于消毒剂-三氯生（TCS）对水生动物中细菌病原体的ARGs传播的影响的信息仍然有限。一种freundii柠檬酸杆菌（C.freundii）从养殖草鱼内脏中分离出带有tet（X4）抗性质粒的菌株，以及随后从弗伦迪C.freundii到大肠杆菌C600的共轭转移频率(E.大肠杆菌C600)在不同的交配时间下进行了分析，温度,和比率。检测了不同浓度的TCS（0.02、0.2、2、20、200和2000μg/L）对共轭转移的影响。共轭转移的最佳条件是在37°C下8h，交配比为2：1或1：1（C。freundii：大肠杆菌C600）。在TCS处理下，接合转移频率显着提高，在2.00μg/LTCS下达到最大值，是对照组的18.39倍。活性氧（ROS），超氧化物歧化酶(SOD)和过氧化氢酶(CAT)活性,在TCS胁迫下，弗氏梭菌和大肠杆菌C600的细胞膜通透性明显增加。扫描电子显微镜显示，接合菌株的细胞膜表面出现皱纹和凹陷，甚至在2.00μg/LTCS时破碎，在200.00μg/LTCS时裂解甚至破裂。此外,TCS上调氧化应激基因的表达水平(katE，hemF,bcp,hema,katG,ahpF,和ahpC)和细胞膜相关基因(fimC，供体和受体细菌的bamE和ompA）。基因本体论（GO）富集显示与菌毛相关的类别发生了显着变化，porin活动,跨膜转运蛋白活性，转移酶活性，水解酶活性，物质运输和新陈代谢。一起来看,抗tet(X4)质粒可以在不同病原体之间水平传播，TCS可以促进抗性质粒的繁殖。
