Balagué C, Stürtz N, Duffard R, Evangelista de Duffard A M
Experimental Toxicology Laboratory, Faculty of Biochemical and Pharmaceutical Sciences, National University of Rosario, Suipacha 570 (2000) Rosario, Argentina.
Environ Toxicol. 2001;16(1):43-53. doi: 10.1002/1522-7278(2001)16:1<43::aid-tox50>3.0.co;2-r.
2,4-Dichlorophenoxyacetic acid (2,4-D) is a herbicide widely used in the world and mainly excreted by the renal route in exposed humans and animals. Herbicides can affect other nontarget organisms, such as Escherichia coli. We observed that a single exposure to 1 mM 2,4-D diminished growth and total protein content in all E. coli strains tested in vitro. In addition, successive exposures to 0.01 mM 2,4-D had a toxic effect decreasing growth up to early stationary phase. Uropathogenic E. coli adhere to epithelial cells mediated by fimbriae, adhesins, and hydrophobic properties. 2,4-D exposure of uropathogenic E. coli demonstrated altered hydrophobicity and fimbriation. Hydrophobicity index values obtained by partition in p-xylene/water were 300-420% higher in exposed cells than in control ones. Furthermore, values of hemagglutination titer, protein contents in fimbrial crude extract, and electron microscopy demonstrated a significant diminution of fimbriation in treated cells. Other envelope alterations could be detected, such as lipoperoxidation, evidenced by decreased polyunsaturated fatty acids and increased lipid degradation products (malonaldehyde), and motility diminution. These alterations decreased cell adherence to erythrocytes, indicating a diminished pathogenic capacity of the 2,4-D-exposed E. coli.
2,4-二氯苯氧乙酸（2,4-D）是一种在全球广泛使用的除草剂，在接触该除草剂的人类和动物体内主要通过肾脏途径排泄。除草剂会影响其他非靶标生物，如大肠杆菌。我们观察到，体外测试时，单次暴露于1 mM的2,4-D会使所有测试的大肠杆菌菌株的生长和总蛋白含量降低。此外，连续暴露于0.01 mM的2,4-D具有毒性作用，会使生长降低直至早期稳定期。致病性大肠杆菌通过菌毛、黏附素和疏水性介导黏附于上皮细胞。暴露于2,4-D的致病性大肠杆菌表现出疏水性和菌毛形成的改变。通过在对二甲苯/水中分配获得的疏水性指数值，暴露细胞比对照细胞高300%-420%。此外，血凝滴度值、菌毛粗提物中的蛋白质含量以及电子显微镜检查表明，处理过的细胞中菌毛形成显著减少。还可检测到其他包膜改变，如脂质过氧化，表现为多不饱和脂肪酸减少和脂质降解产物（丙二醛）增加，以及运动性降低。这些改变降低了细胞对红细胞的黏附，表明暴露于2,4-D的大肠杆菌致病能力减弱。
