Protective effect of exopolysaccharide colanic acid of Escherichia coli O157:H7 to osmotic and oxidative stress
Protective effect of exopolysaccharide colanic acid of Escherichia coli O157:H7 to osmotic and oxidative stress
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DOI：
10.1016/j.ijfoodmicro.2003.12.004
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发表时间：
2004-06-15
影响因子：
5.4
通讯作者：
Mao, Y
中科院分区：
文献类型：
--
作者：
Chen, JR;Lee, SM;Mao, Y
许多大肠杆菌 O157:H7 菌株在应激下产生由荚膜多糖 (CA) 组成的胞外多糖 (EPS)，并在环境温度下在最小葡萄糖琼脂 (MGA) 上形成粘液菌落。我们实验室之前进行的研究涉及 CA 丰富型 (W6-13) 和 CA 缺陷型 (M4020; wcaD::Ekan') 大肠杆菌 O157:H7 菌株，结果表明 CA 赋予大肠杆菌 O157:H7 耐酸和耐热性。被 CA 覆盖的细胞在酸（pH 4.5、5.5 和 6.5）和热（55 和 60 摄氏度）处理过程中更持久。本研究的目的是研究 CA 对渗透和氧化应激下大肠杆菌 O157:H7 命运的影响。将 W6-13 和 M4020 细胞在 22℃ 下暴露于基本葡萄糖肉汤 (MGB) 中的不同浓度的 NaCl（0.5、1.5 和 2.5 M）和 H2O2（0、10 和 20 mM）。在渗透应激 48 小时和氧化应激 3 小时内测定大肠杆菌 O157:H7 的活菌数。结果表明，缺乏 CA 产生的大肠杆菌 O157:H7 细胞比其野生型亲本更容易受到 NaCl 的影响（P
Many strains of Escherichia coli O157:H7 produce, under stress, an exopolysaccharide (EPS) comprised of colanic acid (CA) and form mucoid colonies on minimal glucose agar (MGA) at ambient temperature. Previous research conducted in our laboratory involving a CA-proficient (W6-13) and a CA-deficient (M4020; wcaD::Ekan') strain of E. coli O157:H7 revealed that CA conferred acid and heat tolerance to E. coli O157:H7. Cells covered with CA were more persistent during acid (pH 4.5, 5.5, and 6.5) and heat (55 and 60 degreesC) treatment. The goal of this research was to study the effect of CA on the fate of E. coli O157:H7 under osmotic and oxidative stress. Cells of W6-13 and M4020 were exposed to various concentrations of NaCl (0.5, 1.5, and 2.5 M) and H2O2 (0, 10, and 20 mM) in minimal glucose broth (MGB) at 22degreesC. Viable counts of E. coli O157:H7 were determined within 48 h of the osmotic stress and 3 h of the oxidative stress. The results suggest that cells of E. coli O157:H7 deficient in CA production are more susceptible than its wild-type parent to NaCl (P