Sensitivity of pathogenic and attenuated E-coli O157:H7 strains to ultraviolet-C light as assessed by conventional plating methods and ethidium monoazide-PCR

文献类型： 外文期刊

第一作者： Yan, Ruixiang

作者： Yan, Ruixiang;Liu, Yanhong;Gurtler, Joshua B.;Fan, Xuetong;Yan, Ruixiang;Killinger, Karen

作者机构：

期刊名称：JOURNAL OF FOOD SAFETY （ 影响因子：1.953； 五年影响因子：1.946 ）

ISSN： 0149-6085

年卷期： 2017 年 37 卷 4 期

页码：

收录情况： SCI

摘要： The UV-C sensitivity of six pathogenic Escherichia coli O157:H7 strains associated with recent outbreaks of foodborne illnesses and five attenuated/nonpathogenic E. coli O157:H7 strains was investigated using conventional plating method, and real time PCR with and without ethidium monoazide (EMA) pretreatment. Results showed that the nonpathogenic/attenuated E. coli ATCC 25922, 6980-2, and 6982-2 had more or similar resistance to UV-C compared to the pathogenic strains. The UV-C inhibition on the PCR amplification of DNA correlated well with UV-C dose, as indicated by the cycle threshold (Ct), regardless of EMA pretreatment. The Ct values increased linearly with increasing UV-C doses. Cell membrane was damaged only at high doses when UV-C inactivated more than 6 log CFU of bacteria. Overall, our results suggest that E. coli strains have different sensitivities to UV-C and that EMA-PCR is a useful tool to assess cell damage caused by UV-C. Practical applicationsUltraviolet (UV) light, as one of the postharvest interventions, is simple to implement and inexpensive for commercial applications. To conduct trials on a large scale or at a commercial setting, nonpathogenic/attenuated surrogates of pathogenic bacteria should be used, due to the difficulty for containment and post-treatment decontamination of equipment and the environment. We demonstrated the variations in UV-C sensitivity among pathogenic and nonpathogenic E. coli strains. Three attenuated/nonpathogenic strains of E. coli had similar sensitivities as the pathogenic strains, and therefore, could serve as surrogates. Furthermore, cell membrane was not affected by moderate doses of UV-C treatments, even though the bacteria were not cultivable. The information will be useful for researchers to conduct scale-up trials, and to optimize UV-C technology for microbial safety enhancement.

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