The effect of probiotics and organic acids on Shiga-toxin 2 gene expression in enterohemorrhagic Escherichia coli O157:H7
The effect of probiotics and organic acids on Shiga-toxin 2 gene expression in enterohemorrhagic Escherichia coli O157:H7
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DOI：
10.1016/j.mimet.2008.01.014
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发表时间：
2008-05-01
影响因子：
2.2
通讯作者：
Thompson, Stacey
中科院分区：
文献类型：
--
作者：
Carey, Christine M.;Kostrzynska, Magdalena;Thompson, Stacey
已知益生菌对各种食源性病原体的生长具有抑制作用，然而，益生菌在产志贺毒素大肠杆菌（STEC）毒力基因表达中的具体作用尚未得到很好的定义。滋贺毒素是高效细菌毒素家族的成员，并且是STEC的主要毒力标志物。滋贺毒素抑制真核细胞中的蛋白质合成，并在出血性结肠炎和溶血性尿毒综合征中发挥作用。STEC具有滋贺毒素1（Stx 1）和滋贺毒素2（Stx 2），两者均具有A和B亚基。虽然含有Stx 1和Stx 2的STEC已从出血性结肠炎患者中分离出来，但Stx 2更常与人类疾病并发症相关。因此，研究了乳杆菌属、片球菌属和双歧杆菌属菌株对STEC中stx 2A表达水平的影响。乳酸菌和双歧杆菌分离自农场动物、乳制品和人类来源，包括L。rhamnosus GG，L.弯曲的L. [医]植物詹氏湖嗜酸乳杆菌L.干酪湖（L. casei）罗伊氏酵母、乳酸酵母、酿酒酵母、戊糖酵母、B. B. thermophilum，嗜热拟杆菌B. boum，B. suis和B.动物E. coli O 157：H7（EDL 933）与亚致死浓度的每种益生菌菌株共孵育。在RNA提取和cDNA合成之后，根据比较临界阈值（Ct）实时PCR确定相对stx 2A mRNA水平。将数据标准化为内源性对照甘油醛-3-磷酸脱氢酶（GAPDH），并比较处理和未处理的STEC之间的stx 2A表达水平。对于所有测试的益生菌菌株观察到，当与对照培养物相比时，stx 2A被下调。益生菌生产的有机酸，如所示的pH值的降低，影响stx 2A基因的表达。皇冠版权所有（c）2008年出版的爱思唯尔B. V.保留所有权利。
Probiotics are known to have an inhibitory effect against the growth of various foodborne pathogens, however, the specific role of probiotics in Shiga-toxin-producing Escherichia coli (STEC) virulence gene expression has not been well defined. Shiga toxins are members of a family of highly potent bacterial toxins and are the main virulence marker for STEC. Shiga toxins inhibit protein synthesis in eukaryotic cells and play a role in hemorrhagic colitis and hemolytic uremic syndrome. STEC possesses Shiga toxin 1 (Stx1) and Shiga toxin 2 (Stx2), both of which have A and B subunits. Although STEC containing both Stx1 and Stx2 has been isolated from patients with hemorrhagic colitis, Stx2 is more frequently associated with human disease complications. Thus, the effect of Lactobacillus, Pediococcus, and Bifidobacterium strains on stx2A expression levels in STEC was investigated. Lactic acid bacteria and bifidobacteria were isolated from farm animals, dairy, and human sources and included L. rhamnosus GG, L. curvatus, L. plantarum, L. jensenii, L. acidophilus, L. casei, L. reuteri, P. acidilactici, P. cerevisiae, P. pentosaceus, B. thermophilum, B. boum, B. suis and B. animalis. E. coli O157:H7 (EDL 933) was coincubated with sub-lethal concentrations of each probiotic strain. Following RNA extraction and cDNA synthesis, relative stx2A mRNA levels were determined according to a comparative critical threshold (Ct) real-time PCR. Data were normalized to the endogenous control glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and the level of stx2A expression between treated and untreated STEC was compared. Observed for all probiotic strains tested, stx2A was down-regulated, when compared to the control culture. Probiotic production of organic acids, as demonstrated by a decrease in pH, influenced stx2A gene expression. Crown Copyright (c) 2008 Published by Elsevier B.V. All rights reserved.