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首页> 外文期刊>Applied Microbiology >Distinct Transcriptional Profiles and Phenotypes Exhibited by Escherichia coli O157:H7 Isolates Related to the 2006 Spinach-Associated Outbreak
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Distinct Transcriptional Profiles and Phenotypes Exhibited by Escherichia coli O157:H7 Isolates Related to the 2006 Spinach-Associated Outbreak

机译：与2006年菠菜相关暴发相关的大肠杆菌O157：H7分离株表现出的独特转录谱和表型

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In 2006, a large outbreak of Escherichia coli O157:H7 was linked to the consumption of ready-to-eat bagged baby spinach in the United States. The likely sources of preharvest spinach contamination were soil and water that became contaminated via cattle or feral pigs in the proximity of the spinach fields. In this study, we compared the transcriptional profiles of 12 E. coli O157:H7 isolates that possess the same two-enzyme pulsed-field gel electrophoresis (PFGE) profile and are related temporally or geographically to the above outbreak. These E. coli O157:H7 isolates included three clinical isolates, five isolates from separate bags of spinach, and single isolates from pasture soil, river water, cow feces, and a feral pig. The three clinical isolates and two spinach bag isolates grown in cultures to stationary phase showed decreased expression of many σ~(S)-regulated genes, including gadA , osmE , osmY , and katE , compared with the soil, water, cow, feral pig, and the other three spinach bag isolates. The decreased expression of these σ~(S)-regulated genes was correlated with the decreased resistance of the isolates to acid stress, osmotic stress, and oxidative stress but increases in scavenging ability. We also observed that intraisolate variability was much more pronounced among the clinical and spinach isolates than among the environmental isolates. Together, the transcriptional and phenotypic differences of the spinach outbreak isolates of E. coli O157:H7 support the hypothesis that some variants within the spinach bag retained characteristics of the preharvest isolates, whereas other variants with altered gene expression and phenotypes infected the human host.
机译：2006年，大肠杆菌O157：H7的大规模爆发与美国食用即食袋装菠菜的消费有关。菠菜收获前污染的可能来源是土壤和水，它们被菠菜田附近的牛或野猪污染。在这项研究中，我们比较了12个大肠杆菌O157：H7分离株的转录谱，这些分离株具有相同的两个酶脉冲场凝胶电泳（PFGE）谱，并且在时间或地理上与上述爆发有关。这些大肠杆菌O157：H7分离株包括3种临床分离株，分别来自菠菜袋的5种分离株，以及牧场土壤，河水，牛粪和野猪的单个分离株。与土壤，水，牛，野猪相比，培养至静止期的三种临床分离株和两种菠菜袋分离株显示许多受σ〜（S）调控的基因（包括gadA，osmE，osmY和katE）的表达降低。 ，以及其他三个菠菜袋菌株。这些σ〜（S）调节基因的表达减少与分离株对酸胁迫，渗透压和氧化胁迫的抗性降低有关，但清除能力增强。我们还观察到，临床分离物和菠菜分离物中分离物内部的变异性要比环境分离物中的差异大得多。一起，大肠杆菌O157：H7菠菜暴发分离株的转录和表型差异支持了这样的假说：菠菜袋内的某些变体保留了收获前分离物的特征，而其他具有改变的基因表达和表型的变体感染了人类宿主。

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