Evaluation of parameters governing dark and photo-repair in UVC-irradiated Escherichia coli
Evaluation of parameters governing dark and photo-repair in UVC-irradiated Escherichia coli
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DOI：
10.1039/d1ew00644d
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发表时间：
2021-12-23
影响因子：
5
通讯作者：
Snow, Samuel D.
中科院分区：
文献类型：
--
作者：
Maghsoodi, Mostafa;Lowry, Grace L.;Snow, Samuel D.
在经过数十年的紫外线消毒实践以及有关病原体在紫外线暴露后经历黑暗或照片修复的潜力的大量研究之后，紫外线发射二极管（LED）技术的最新进展促使人们对紫外线暴露后的细菌重新激活和再生过程提示。光板条件的方面值得特别注意，因为即使对常规汞蒸气灯的研究也没有充分表征这些参数。废水在排出后遇到了广泛的环境条件（例如，太阳照射和溶解有机物），这可能会影响修复过程，并最终导致过度估计去除病原体。这里使用大肠杆菌来研究UV254和UV278辐射后改变重新激活条件的影响。 UV254和UV278剂量分别诱导大肠杆菌的3.0对数灭活，需要13.75 +/- 0.4 MJ CM（-2）和28.3 +/- 0.8 MJ CM（-2）。具体而言，在溶解的有机物（DOM）含量和光电反应波长和强度之间，光电反应条件变化。光电反应比黑暗修复更高的对数回收率高，范围为0.8至1.8 log差异，但是在UVA照射下发生了继发消毒效应。在光电反应过程中，腐殖酸抑制了UV278剂量大肠杆菌的初始修复，但培养基增强了两种剂量波长的恢复。 UV395，UV365和可见光下的光电反应曲线取决于频率和时间，在暴露于可见光和最少365 nm以下时，观察到更多的再生。大肠杆菌对UVA的敏感性通过事先接触UVC而增加。
After decades of UV disinfection practice and numerous studies on the potential for pathogens to undergo dark or photo-repair after UV exposure, recent advances in UV light emitting diode (LED) technologies prompt renewed attention to bacterial reactivation and regrowth processes after UV exposure. The aspect of photorepair conditions warrants particular attention, because even studies on conventional mercury vapor lamps have not sufficiently characterized these parameters. Wastewater encounters a wide range of environmental conditions upon discharge (e.g., solar irradiation and dissolved organics) which may affect repair processes and ultimately lead to overestimations of pathogen removal. Escherichia coli was used here to investigate the impacts of changing reactivation conditions after UV254 and UV278 irradiation. UV254 and UV278 doses of 13.75 +/- 0.4 mJ cm(-2) and 28.3 +/- 0.8 mJ cm(-2) were required to induce a 3.0 log inactivation of E. coli, respectively. Specifically, photoreactivation conditions were varied across dissolved organic matter (DOM) content and photoreactivation wavelengths and intensities. Photoreactivation achieved higher log recoveries than dark repair, ranging from 0.8 to 1.8 log differences, but a secondary disinfection effect occurred under UVA irradiation. During photoreactivation, humic acid inhibited the initial repair of UV278-dosed E. coli, but culture media enhanced recovery for both dosage wavelengths. Photoreactivation profiles under UV395, UV365, and visible light depended on both fluence and time, with more regrowth observed upon exposure to visible light and the least under 365 nm. The susceptibility of E. coli to UVA was increased by prior exposure to UVC.