Oxidative DNA damage caused by pulsed discharge with cavitation on the bactericidal function
Oxidative DNA damage caused by pulsed discharge with cavitation on the bactericidal function
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DOI：
10.1088/0022-3727/48/36/365401
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发表时间：
2015-08
期刊：
影响因子：
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通讯作者：
K. Kudo;Hironori Ito;S. Ihara;H. Terato
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文献类型：
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作者：
K. Kudo;Hironori Ito;S. Ihara;H. Terato
基于等离子体的技术有望在废水净化中得到实际应用，具有杀死受污染微生物和降解难降解物质的潜力。在本研究中，我们分析了等离子体处理的细菌细胞中的氧化DNA损伤，以揭示其在杀菌过程中的机制。将大肠杆菌细胞悬液暴露于通过施加约1 kV的交流电压而产生的等离子体中，该等离子体具有由水空化形成的气泡，称为空化脉冲放电。染色体DNA损伤，如双链断裂（DSB）和氧化性碱基损伤，与所施加的能量成比例增加，通过电泳和质谱分析确定。在鉴定的碱基病变中，与未处理的样品相比，染色体DNA中8-羟基鸟嘌呤（8-OH-G）和5-羟基胞嘧啶（5-OH-C）的产量分别增加了4倍和15倍。从暴露于等离子体的质粒DNA衍生的子代DNA序列表明，5-OH-C的产生速率超过8-OH-G的产生速率，因为G：C到A：T的转换占所有碱基变化的65%，但仅观察到少数G：C到T：A的颠换。结果表明，E.大肠杆菌细胞的减少与所施加的能量的增加成正比。因此，等离子体诱导的杀菌机制似乎与对细菌DNA造成的氧化损伤有关。通过观察等离子体暴露后羟基自由基和过氧化氢分子的产生证实了这些结果。我们还将我们的结果与等离子体与137 Cs γ射线（作为众所周知的ROS发生器）获得的结果进行了比较，以确认所涉及的DNA损伤机制。
Plasma-based techniques are expected to have practical use for wastewater purification with a potential for killing contaminated microorganisms and degrading recalcitrant materials. In the present study, we analysed oxidative DNA damage in bacterial cells treated by the plasma to unveil its mechanisms in the bactericidal process. Escherichia coli cell suspension was exposed to the plasma induced by applying an alternating-current voltage of about 1 kV with bubbling formed by water-cavitation, termed pulsed discharge with cavitation. Chromosomal DNA damage, such as double strand break (DSB) and oxidative base lesions, increased proportionally with the applied energy, as determined by electrophoretic and mass spectrometric analyses. Among the base lesions identified, the yields of 8-hydroxyguanine (8-OH-G) and 5-hydroxycytosine (5-OH-C) in chromosomal DNA increased by up to 4- and 15-fold, respectively, compared to untreated samples. The progeny DNA sequences, derived from plasmid DNA exposed to the plasma, indicated that the production rate of 5-OH-C exceeded that of 8-OH-G, as G:C to A:T transitions accounted for 65% of all base changes, but only a few G:C to T:A transversions were observed. The cell viabilities of E. coli cells decreased in direct proportion to increases in the applied energy. Therefore, the plasma-induced bactericidal mechanism appears to relate to oxidative damage caused to bacterial DNA. These results were confirmed by observing the generation of hydroxyl radicals and hydrogen peroxide molecules following the plasma exposure. We also compared our results with the plasma to those obtained with 137Cs γ-rays, as a well-known ROS generator to confirm the DNA-damaging mechanism involved.