Gene Expression Induced in Escherichia coli O157:H7 upon Exposure to Model Apple Juice
Gene Expression Induced in Escherichia coli O157:H7 upon Exposure to Model Apple Juice
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DOI：
10.1128/aem.02841-08
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发表时间：
2009-06-01
影响因子：
4.4
通讯作者：
Whittam, Thomas S.
中科院分区：
文献类型：
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作者：
Bergholz, Teresa M.;Vanaja, Sivapriya Kailasan;Whittam, Thomas S.
大肠杆菌O157：H7通过在各种食品载体中传播引起严重的食源性疾病爆发，包括未经高温消毒的苹果汁，干腊肠和菠菜。为了了解这种病原体如何应对食品环境的多重压力，我们比较了暴露于模型苹果汁之前和之后的全球转录模式。使用探测4，886个开放阅读框的微阵列，在模型苹果汁（pH 3.5）中10分钟后评估中期指数期和静止期细胞的转录组。共331个基因显着诱导后暴露的细胞模型苹果汁，包括参与酸，渗透压和氧化应激反应以及信封应激反应的基因。酸和渗透胁迫反应基因，包括asr，osmC，osmB和osmY，显着诱导响应模型苹果汁。如CpxR和Rcs磷酸化介导基因的表达增加所证明的，多重包膜应激反应被激活。由CpxR（cpxP，degP和htpX）控制的基因显着诱导暴露于苹果汁后2至15倍。CpxRA的灭活导致O157：H7在模型苹果汁中的存活率显著降低。在模型苹果汁中诱导的331个基因中，104个是O157特异性基因，包括编码第三类分泌效应子的基因（espJ、espB、espM2、espL3和espZ）。阐明O157：H7对酸性食物的反应可以深入了解这种病原体如何能够在食物基质中生存，以及暴露于食物如何影响随后的传播和毒力。
Escherichia coli O157:H7 has caused serious outbreaks of food-borne illness via transmission in a variety of food vehicles, including unpasteurized apple juice, dried salami, and spinach. To understand how this pathogen responds to the multiple stresses of the food environment, we compared global transcription patterns before and after exposure to model apple juice. Transcriptomes of mid-exponential-and stationary-phase cells were evaluated after 10 min in model apple juice (pH 3.5) using microarrays probing 4,886 open reading frames. A total of 331 genes were significantly induced upon exposure of cells to model apple juice, including genes involved in the acid, osmotic, and oxidative stress responses as well as the envelope stress response. Acid and osmotic stress response genes, including asr, osmC, osmB, and osmY, were significantly induced in response to model apple juice. Multiple envelope stress responses were activated as evidenced by increased expression of CpxR and Rcs phosphorelay- controlled genes. Genes controlled by CpxR (cpxP, degP, and htpX) were significantly induced 2- to 15-fold upon exposure to apple juice. Inactivation of CpxRA resulted in a significant decrease in survival of O157:H7 in model apple juice compared to the isogenic parent strain. Of the 331 genes induced in model apple juice, 104 are O157-specific genes, including those encoding type three secretion effectors (espJ, espB, espM2, espL3, and espZ). Elucidating the response of O157:H7 to acidic foods provides insight into how this pathogen is able to survive in food matrices and how exposure to foods influences subsequent transmission and virulence.