这项研究解决的问题是了解微波辐射如何能够降解大肠杆菌的基因组DNA。此外,进行了一项比较研究,以评估高通量自动电泳平台在微波辐射下定量DNA降解的适用性。总的来说,本研究采用自动凝胶电泳技术研究了微波辐射下大肠杆菌基因组DNA的降解。为了检查微波暴露下的活生物体和基因组DNA的降解,我们使用了三种方法:(1)微波后暴露,其中大肠杆菌采用改良的mTEC琼脂法采用膜过滤技术进行计数;(2)微波样品提取的基因组DNA采用Qubit方法进行定量;(3)自动凝胶电泳,TapeStation4200用于检查微波样品的提取DNA条带。此外,为了检查微波的影响,从粪便样品(奶牛粪便)中分离大肠杆菌菌落,这些菌落过夜生长以制备新鲜的大肠杆菌培养物,并将该培养物暴露于微波辐射下三个持续时间:(1)2分钟;(2)5分钟;(3)8分钟。总的来说,量子位值(ng/µL)与自动凝胶电泳的结果成正比,TapeStation4200,DNA完整性编号(DINs)。来自暴露研究的样本(2分钟,5分钟,和8分钟)显示没有活的大肠杆菌。初始大肠杆菌水平(在0分钟微波暴露)为5×108CFU/mL,并且大肠杆菌水平在微波暴露的2分钟内降低至不可检测的水平。Qubit和TapeStation测量之间的关系是线性的,除非DNA水平低于2ng/µL。在微波暴露8分钟内,大肠杆菌DNA完整性降低61.7%,DNA浓度降低了81.6%。本研究的总体结论是微波辐射对大肠杆菌基因组DNA有显著影响,和大肠杆菌长时间暴露于微波可因此导致基因组DNA完整性和DNA浓度的损失。
The problem that this study addresses is to understand how microwave radiation is able to degrade genomic DNA of E. coli. In addition, a comparative study was made to evaluate the suitability of a high-throughput automated electrophoresis platform for quantifying the DNA degradation under microwave radiation. Overall, this study investigated the genomic DNA degradation of E. coli under microwave radiation using automated gel electrophoresis. To examine the viable organisms and degradation of genomic DNA under microwave exposure, we used three methods: (1) post-microwave exposure, where E. coli was enumerated using modified mTEC agar method using membrane filtration technique; (2) extracted genomic DNA of microwaved sample was quantified using the Qubit method; and (3) automated gel electrophoresis, the TapeStation 4200, was used to examine the bands of extracted DNA of microwaved samples. In addition, to examine the impacts of microwaves, E. coli colonies were isolated from a fecal sample (dairy cow manure), these colonies were grown overnight to prepare fresh E. coli culture, and this culture was exposed to microwave radiation for three durations: (1) 2 min; (2) 5 min; and (3) 8 min. In general, Qubit values (ng/µL) were proportional to the results of automated gel electrophoresis, TapeStation 4200, DNA integrity numbers (DINs). Samples from exposure studies (2 min, 5 min, and 8 min) showed no viable E. coli. Initial E. coli levels (at 0 min microwave exposure) were 5 × 108 CFU/mL, and the E. coli level was reduced to a non-detectable level within 2 min of microwave exposure. The relationships between Qubit and TapeStation measurements was linear, except for when the DNA level was lower than 2 ng/µL. In 8 min of microwave exposure, E. coli DNA integrity was reduced by 61.7%, and DNA concentration was reduced by 81.6%. The overall conclusion of this study is that microwave radiation had a significant impact on the genomic DNA of E. coli, and prolonged exposure of E. coli to microwaves can thus lead to a loss of genomic DNA integrity and DNA concentrations.