Sakudo Akikazu, Imanishi Yuichiro
Laboratory of Biometabolic Chemistry, School of Health Sciences, Faculty of Medicine, University of the Ryukyus, 207 Uehara, Nishihara, Okinawa, 903-0215, Japan.
NGK Insulators Ltd., 2-56 Suda-cho, Mizuho, Nagoya, 467-8530, Japan.
AMB Express. 2017 Dec;7(1):77. doi: 10.1186/s13568-017-0380-7. Epub 2017 Apr 7.
Shiga toxin (Stx)-producing Escherichia coli (STEC) leads to food poisoning by causing hemorrhagic colitis and hemolytic uremic syndrome. Some STEC produce Shiga toxin 1 (Stx1) and/or Shiga toxin 2 (Stx2), a relatively stable protein toxin, necessitating the development of an efficient inactivation method. Here we applied a nitrogen gas plasma apparatus to the inactivation of Stx. Samples of Stx1 and Stx2 were treated with a nitrogen gas plasma generated by a plasma device using a short high-voltage pulse applied by a static induction thyristor power supply at 1.5 kpps (kilo pulse per second). The recovered Stx samples were then analyzed for immunological and biological activities. Immunochromatography demonstrated that Stx1 and Stx2 were degraded by the gas plasma. Quantification by enzyme-linked immunosorbent assay (ELISA) showed that both toxins were efficiently degraded to less than 1/10th of their original concentration within 5 min of treatment. Western blotting further showed the gas plasma treatment degraded the A subunit, which mediates the toxicity of Stx. Moreover, an assay using HEp-2 cells as an index of cytotoxicity showed that gas plasma treatment reduced the toxic activity of Stx. Therefore, nitrogen gas plasma might be an efficient method for the inactivation of Stx.
产志贺毒素大肠杆菌（STEC）通过引起出血性结肠炎和溶血尿毒综合征导致食物中毒。一些STEC产生志贺毒素1（Stx1）和/或志贺毒素2（Stx2），这是一种相对稳定的蛋白质毒素，因此需要开发一种有效的灭活方法。在此，我们将氮气等离子体装置应用于Stx的灭活。使用由静电感应晶闸管电源以1.5 kpps（每秒千脉冲）施加的短高压脉冲的等离子体装置产生的氮气等离子体处理Stx1和Stx2样品。然后对回收的Stx样品进行免疫和生物学活性分析。免疫层析表明，Stx1和Stx2被气体等离子体降解。通过酶联免疫吸附测定（ELISA）定量显示，两种毒素在处理5分钟内均被有效降解至其原始浓度的十分之一以下。蛋白质印迹进一步表明，气体等离子体处理降解了介导Stx毒性的A亚基。此外，以HEp-2细胞作为细胞毒性指标的试验表明，气体等离子体处理降低了Stx的毒性活性。因此，氮气等离子体可能是一种有效的Stx灭活方法。
