Metal ions, not metal-catalyzed oxidative stress, cause clay leachate antibacterial activity.
Metal ions, not metal-catalyzed oxidative stress, cause clay leachate antibacterial activity.
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金属离子而不是金属催化的氧化应激，会导致粘土浸出抗菌活性。
DOI：
10.1371/journal.pone.0115172
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发表时间：
2014
期刊：
影响因子：
3.7
通讯作者：
Haydel SE
中科院分区：
文献类型：
--
作者：
Otto CC;Koehl JL;Solanky D;Haydel SE
由天然抗菌粘土制备的含水沥滤液（任意指定为CB-L）将金属离子释放到悬浮液中，具有低pH（3.4-5），产生活性氧（ROS）和H2 O2，并且具有高氧化还原电位。为了分离CB粘土混合物的抗菌活性的pH值的作用，我们暴露了三种不同的菌株的大肠杆菌O 157：H7的10%的粘土悬浮液。粘土悬浮液对酸敏感和耐酸的E. coli O 157：H7菌株，而在低pH缓冲液中孵育导致活力的最小降低，表明单独的低pH不介导抗菌活性。流行的假说是金属离子参与氧化还原循环并产生ROS，导致对大分子的氧化损伤并导致细胞死亡。然而，E.大肠杆菌细胞显示，没有增加DNA或蛋白质的氧化损伤和脂质过氧化作用后，暴露于抗菌浸出液略有增加。此外，补充许多ROS清除剂消除了脂质过氧化，但没有拯救CB-L介导的杀伤细胞。相比之下，用EDTA（一种广谱金属螯合剂）补充CB-L可减少杀伤。最后，与有氧环境相比，CB-L在缺氧环境中对细胞同样致命。因此，ROS不是致死活性所必需的，也不会导致CB-L的毒性。我们得出结论，粘土介导的杀伤不是由于氧化损伤，而是由于毒性直接与释放的金属离子。
Aqueous leachates prepared from natural antibacterial clays, arbitrarily designated CB-L, release metal ions into suspension, have a low pH (3.4–5), generate reactive oxygen species (ROS) and H2O2, and have a high oxidation-reduction potential. To isolate the role of pH in the antibacterial activity of CB clay mixtures, we exposed three different strains of Escherichia coli O157:H7 to 10% clay suspensions. The clay suspension completely killed acid-sensitive and acid-tolerant E. coli O157:H7 strains, whereas incubation in a low-pH buffer resulted in a minimal decrease in viability, demonstrating that low pH alone does not mediate antibacterial activity. The prevailing hypothesis is that metal ions participate in redox cycling and produce ROS, leading to oxidative damage to macromolecules and resulting in cellular death. However, E. coli cells showed no increase in DNA or protein oxidative lesions and a slight increase in lipid peroxidation following exposure to the antibacterial leachate. Further, supplementation with numerous ROS scavengers eliminated lipid peroxidation, but did not rescue the cells from CB-L-mediated killing. In contrast, supplementing CB-L with EDTA, a broad-spectrum metal chelator, reduced killing. Finally, CB-L was equally lethal to cells in an anoxic environment as compared to the aerobic environment. Thus, ROS were not required for lethal activity and did not contribute to toxicity of CB-L. We conclude that clay-mediated killing was not due to oxidative damage, but rather, was due to toxicity associated directly with released metal ions.
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