Adaptation to sublethal environmental stresses protects Listeria monocytogenes against lethal preservation factors
Adaptation to sublethal environmental stresses protects Listeria monocytogenes against lethal preservation factors
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DOI：
10.1128/aem.63.4.1252-1255.1997
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发表时间：
1997-04-01
影响因子：
4.4
通讯作者：
Yousef, AE
中科院分区：
文献类型：
--
作者：
Lou, YQ;Yousef, AE
一次致死量的乙醇(5%,卷/卷),酸(盐酸、pH 4.5到5.0),过氧化氢(500 ppm),或生理盐水(7%,wt /卷)被添加到单核细胞增多性李斯特氏菌文化在指数期,细胞被允许增加1 h,对数生长期细胞也热震惊45度1 h,然后stress-adapted细胞受到下列因素在指定的致命levels-NaCl (25%, wt /卷)、乙醇(17.5%,卷/卷),过氧化氢(0.1%,wt /卷),酸(pH值3.5),在0.1 M pH 7.0的磷酸盐缓冲液中饥饿（长达300 h），在Trypticase大豆琼脂酵母提取物上测定处理后病原菌的活菌计数，并构建存活区。计算对照曲线与处理曲线之间的log(10) CFU/ml)，表示适应亚致死应激因子产生的保护作用，适应pH为4.5 ~ 5.0或5%乙醇显著（P < 0.05）提高了单核增生乳杆菌对致死剂量酸、乙醇和H2O2的抗性。乙醇处理显著（P < 0.05）提高了对25% NaCl的抗性。当单核增生乳杆菌适应500ppm H2O2、7% NaCl和高温时，病原菌对1%过氧化氢的抗性显著提高（P < 0.05），热休克显著提高了对乙醇和NaCl的抗性（P < 0.05），因此单核增生乳杆菌适应环境胁迫后是否发生胁迫保护取决于所遇到的胁迫类型和致死因子。这种“应力硬化”在当前的食品加工技术改进或开发新技术时应予以考虑。
A sublethal dose of ethanol (5%, vol/vol), acid (HCl, pH 4.5 to 5.0), H2O2 (500 ppm), or NaCl (7%, wt/vol) was added to a Listeria monocytogenes culture at the exponential phase, and the cells were allowed to grow for 1 h, Exponential-phase cells also were heat shocked at 45 degrees C for 1 h, The stress-adapted cells were then subjected to the following factors at the indicated lethal levels-NaCl (25%, wt/vol), ethanol (17.5%, vol/vol), hydrogen peroxide (0.1%, wt/vol), acid (pH 3.5), and starvation in 0.1 M phosphate buffer at pH 7.0 (up to 300 h), Viable counts of the pathogen, after the treatment, were determined on Trypticase soy agar-yeast extract, and survivor plots were constructed, The area (h . log(10) CFU/ml) between the control and treatment curves was calculated to represent the protective effect resulting from adaptation to the sublethal stress factor, Adaptation to pH 4.5 to 5.0 or 5% ethanol significantly (P < 0.05) increased the resistance of L. monocytogenes to lethal doses of acid, ethanol, and H2O2. Adaptation to ethanol significantly (P < 0.05) increased the resistance to 25% NaCl. When L. monocytogenes was adapted to 500 ppm of H2O2, 7% NaCl, or heat, resistance of the pathogen to 1% hydrogen peroxide increased significantly (P < 0.05), Heat shock significantly (P < 0.05) increased the resistance to ethanol and NaCl, Therefore, the occurrence of stress protection after adaptation of L. monocytogenes to environmental stresses depends on the type of stress encountered and the lethal factor applied, This ''stress hardening'' should be considered when current food processing technologies are modified or new ones are developed.