Department of Food Science, Rutgers University, New Brunswick, New Jersey, USA.
Appl Environ Microbiol. 2012 Aug;78(16):5882-9. doi: 10.1128/AEM.01095-12. Epub 2012 Jun 15.
Consumption of fresh and fresh-cut fruits and vegetables contaminated with Escherichia coli O157:H7 has resulted in hundreds of cases of illness and, in some instances, death. In this study, the influence of cell surface structures of E. coli O157:H7, such as flagella, curli fimbriae, lipopolysaccharides, or exopolysaccharides, on plant defense responses and on survival or colonization on the plant was investigated. The population of the E. coli O157:H7 ATCC 43895 wild-type strain was significantly lower on wild-type Arabidopsis plants than that of the 43895 flagellum-deficient mutant. The population of the E. coli O157:H7 43895 flagellum mutant was greater on both wild-type and npr1-1 mutant (nonexpressor of pathogenesis-related [PR] genes) plants and resulted in less PR gene induction, estimated based on a weak β-glucuronidase (GUS) signal, than did the 43895 wild-type strain. These results suggest that the flagella, among the other pathogen-associated molecular patterns (PAMPs), made a substantial contribution to the induction of plant defense response and contributed to the decreased numbers of the E. coli O157:H7 ATCC 43895 wild-type strain on the wild-type Arabidopsis plant. A curli-deficient E. coli O157:H7 86-24 strain survived better on wild-type Arabidopsis plants than the curli-producing wild-type 86-24 strain did. The curli-deficient E. coli O157:H7 86-24 strain exhibited a GUS signal at a level substantially lower than that of the curli-producing wild-type strain. Curli were recognized by plant defense systems, consequently affecting bacterial survival. The cell surface structures of E. coli O157:H7 have a significant impact on the induction of differential plant defense responses, thereby impacting persistence or survival of the pathogen on plants.
食用受大肠杆菌 O157:H7 污染的新鲜和新鲜切割的水果和蔬菜已导致数百例疾病，在某些情况下还导致死亡。在这项研究中，研究了大肠杆菌 O157:H7 的细胞表面结构，如鞭毛、卷曲菌毛、脂多糖或胞外多糖，对植物防御反应以及在植物上的存活或定植的影响。与 43895 鞭毛缺陷突变体相比，野生型拟南芥植物上大肠杆菌 O157:H7 ATCC 43895 野生型菌株的种群数量明显较低。大肠杆菌 O157:H7 43895 鞭毛突变体在野生型和 npr1-1 突变体（不表达与发病相关的基因 [PR]基因）植物上的种群数量更大，并且与 43895 野生型菌株相比，PR 基因的诱导更少，估计基于弱β-葡萄糖醛酸酶（GUS）信号。这些结果表明，鞭毛与其他病原体相关分子模式（PAMPs）一起，对植物防御反应的诱导做出了实质性贡献，并有助于减少大肠杆菌 O157:H7 ATCC 43895 野生型菌株在野生型拟南芥植物上的数量。与产卷曲菌的野生型 86-24 菌株相比，卷曲菌缺陷型大肠杆菌 O157:H7 86-24 菌株在野生型拟南芥植物上的存活能力更好。卷曲菌缺陷型大肠杆菌 O157:H7 86-24 菌株的 GUS 信号水平明显低于产卷曲菌的野生型菌株。植物防御系统识别卷曲菌，从而影响细菌的存活。大肠杆菌 O157:H7 的细胞表面结构对诱导植物防御反应的差异有重大影响，从而影响病原体在植物上的持续存在或生存。
