Tecnología de los Alimentos, Facultad de Veterinaria de Zaragoza, Universidad de Zaragoza, C/ Miguel Servet, 177, 50013, Zaragoza, Spain.
Int J Food Microbiol. 2010 May 30;140(1):26-33. doi: 10.1016/j.ijfoodmicro.2010.02.017. Epub 2010 Feb 19.
The ability of Staphylococcus aureus to develop stress resistance responses was investigated. Exponential growth phase cells of S. aureus CECT 4459 were exposed to sublethal conditions (acid and alkaline pH, hydrogen peroxide, and heat) and then the acquisition of resistance to acid (pH 2.5), alkali (pH 12.0), hydrogen peroxide (50mM), and heat (58 degrees C) was determined. Conditions resulting in the maximum development of homologous resistance (tolerance to the same stress), while preventing lethal effects in the population, were pH 4.5 (2h), pH 9.5 (30 min), 0.05 mM H(2)O(2) (30 min), and 45 degrees C (2h). Under these adaptation conditions, times for the first decimal reduction (TFDC) to a lethal treatment at acid pH, alkaline pH, hydrogen peroxide, and heat were increased by a factor of 1.6, 2, 2, and 6, respectively. The presence of chloramphenicol or rifampicin in the adaptation medium completely abolished the increase in homologous resistance to acid pH and to hydrogen peroxide. By contrast, the development of homologous resistance to alkaline pH resulted independently of the presence of either chloramphenicol or rifampicin. S. aureus heat resistance increased in the presence of the inhibitors during the heat shock, but only partially. In some cases, the exposure to a given stress induced cross-protection against other agents. Protective combinations of sublethal stress and lethal agents were: acid pH-heat, acid pH-hydrogen peroxide, alkaline pH-hydrogen peroxide, heat-acid pH, and heat-hydrogen peroxide. These combinations of agents applied sequentially should be avoided in food-processing environments.
研究了金黄色葡萄球菌产生应激抗性的能力。将金黄色葡萄球菌 CECT 4459 的指数生长期细胞暴露于亚致死条件（酸和碱性 pH、过氧化氢和热）下，然后测定其对酸（pH 2.5）、碱（pH 12.0）、过氧化氢（50mM）和热（58°C）的抗性获得能力。导致同源抗性（对相同应激的耐受性）最大发展的条件，同时防止群体中的致死效应，是 pH 4.5（2 小时）、pH 9.5（30 分钟）、0.05mM H2O2（30 分钟）和 45°C（2 小时）。在这些适应条件下，酸 pH、碱 pH、过氧化氢和热致死处理的第一个十进制减少时间（TFDC）分别增加了 1.6、2、2 和 6 倍。在适应培养基中存在氯霉素或利福平完全消除了对酸 pH 和过氧化氢的同源抗性增加。相比之下，碱性 pH 的同源抗性的发展独立于氯霉素或利福平的存在。金黄色葡萄球菌在热休克期间抑制剂存在的情况下增加了耐热性，但仅部分增加。在某些情况下，暴露于给定的应激会导致对其他试剂的交叉保护。亚致死应激和致死试剂的保护组合为：酸 pH-热、酸 pH-过氧化氢、碱 pH-过氧化氢、热-酸 pH 和热-过氧化氢。在食品加工环境中应避免这些组合剂的顺序应用。
