A fast, reliable, and sensitive method for detection and quantification of Listeria monocytogenes and Escherichia coli O157:H7 in ready-to-eat fresh-cut products by MPN-qPCR.
A fast, reliable, and sensitive method for detection and quantification of Listeria monocytogenes and Escherichia coli O157:H7 in ready-to-eat fresh-cut products by MPN-qPCR.
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DOI：
10.1155/2014/608296
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发表时间：
2014
影响因子：
--
通讯作者：
Beneduce L
中科院分区：
文献类型：
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作者：
Russo P;Botticella G;Capozzi V;Massa S;Spano G;Beneduce L
在本工作中，我们建立了一种MPN定量实时PCR （MPN- qpcr）方法，用于快速、可靠地检测和定量微加工蔬菜中单核增生李斯特菌和大肠杆菌O157:H7。为了验证所提出的技术，将结果与常规MPN进行比较，然后进行表型和生化分析方法。将单核增生乳杆菌和大肠杆菌O157:H7人工接种于鲜切蔬菜中，48小时内可检出低至1 CFU g−1的浓度。单用qPCR对单核增生乳杆菌和大肠杆菌O157:H7富集2小时后的检出限为101 CFU g−1。由于最低限度加工的即食蔬菜的特点是保质期很短，我们的方法可以潜在地解决持续减少微生物分析时间的问题，从而更好地管理质量控制。此外，在两个生产厂从收到原料到保质期的早期阶段，对混合沙拉样品和鲜切甜瓜中致病菌的发生情况进行了监测。未发现样品被单核增生乳杆菌污染。一份生拌沙拉样本呈H7肠出血性血清型阳性。
In the present work we developed a MPN quantitative real-time PCR (MPN-qPCR) method for a fast and reliable detection and quantification of Listeria monocytogenes and Escherichia coli O157:H7 in minimally processed vegetables. In order to validate the proposed technique, the results were compared with conventional MPN followed by phenotypic and biochemical assays methods. When L. monocytogenes and E. coli O157:H7 were artificially inoculated in fresh-cut vegetables, a concentration as low as 1 CFU g−1 could be detected in 48 hours for both pathogens. qPCR alone allowed a limit of detection of 101 CFU g−1 after 2 hours of enrichment for L. monocytogenes and E. coli O157:H7. Since minimally processed ready-to-eat vegetables are characterized by very short shelf life, our method can potentially address the consistent reduction of time for microbial analysis, allowing a better management of quality control. Moreover, the occurrences of both pathogenic bacteria in mixed salad samples and fresh-cut melons were monitored in two production plants from the receipt of the raw materials to the early stages of shelf life. No sample was found to be contaminated by L. monocytogenes. One sample of raw mixed salad was found positive to an H7 enterohemorrhagic serotype.