Martínez Beatriz, Obeso Jose María, Rodríguez Ana, García Pilar
Instituto de Productos Lácteos de Asturias (IPLA-CSIC). Apdo. 85. 33300- Villaviciosa, Asturias, Spain.
Int J Food Microbiol. 2008 Mar 20;122(3):253-8. doi: 10.1016/j.ijfoodmicro.2008.01.011. Epub 2008 Jan 26.
The combined effect of nisin and two lytic phages against Staphylococcus aureus was assessed. In short-time challenge experiments performed in pasteurized milk, a synergistic effect was observed. However, the development of nisin-adapted cells seriously compromised bacteriophage activity. A nisin-adapted strain became partially resistant to both phages. Efficiency of plaquing as well as adsorption values differed. Changes on the bacterial surface, often linked to nisin resistance, could account for the phenotypes observed, most likely by interfering with binding/recognition of phage receptors. The nisin-adapted strain was significantly less hydrophobic and with a higher positive net charge as shown by the lack of binding of cytochrome c and nisin. Loss of the nisin resistant phenotype restored phage susceptibility. In contrast, bacteriophage insensitive mutants were not nisin resistant. The results indicate that careful use of nisin and bacteriophages in combination is required for control of S. aureus in dairy products.
评估了乳酸链球菌素和两种裂解性噬菌体对金黄色葡萄球菌的联合作用。在巴氏杀菌牛奶中进行的短期挑战实验中，观察到了协同效应。然而，适应乳酸链球菌素的细胞的出现严重损害了噬菌体的活性。一株适应乳酸链球菌素的菌株对两种噬菌体都产生了部分抗性。噬菌斑形成效率和吸附值有所不同。细菌表面的变化通常与乳酸链球菌素抗性有关，这可能是观察到的表型的原因，很可能是通过干扰噬菌体受体的结合/识别。适应乳酸链球菌素的菌株疏水性显著降低，净正电荷更高，这表现为细胞色素c和乳酸链球菌素缺乏结合。乳酸链球菌素抗性表型的丧失恢复了噬菌体敏感性。相反，噬菌体不敏感突变体对乳酸链球菌素不具有抗性。结果表明，在乳制品中控制金黄色葡萄球菌需要谨慎联合使用乳酸链球菌素和噬菌体。
