In this study, we describe the development of an automated immunomagnetic separation device combined with real-time polymerase chain reaction (PCR) for detecting foodborne bacteria. Immunomagnetic separation (IMS) is a well-known method for the separation and concentration of target bacteria from a large volume of food samples. Magnetic beads functionalized with an antibody provide selectivity for target bacteria such as Escherichia coli O157:H7. Moreover, compared to conventional methods, real-time PCR enables high-sensitivity detection of target bacteria. The method proposed in this study involves three steps: (1) pre-enrichment, (2) automated IMS and concentration of target bacteria, and (3) detection of target bacteria by real-time PCR. Using food samples with a working sample volume as large as 250 mL, the whole process only requires 3 h. As a result, target bacteria in the range of 10¹–10² colony-forming units per mg or g of sample can be detected in food samples, such as milk, ground beef, and cabbage, by using the proposed approach. We anticipate that the automated IMS system combined with real-time PCR will contribute to the development of a fully automated system for detecting foodborne bacteria and serve as a multi-tester for a variety of bacterial strains in the capacity of a sample-to-answer device in the near future.

中文翻译：

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自动免疫磁分离结合实时荧光定量PCR检测食品中的大肠杆菌O157：H7

在这项研究中，我们描述了结合实时聚合酶链反应（PCR）来检测食源性细菌的自动免疫磁分离设备的开发。免疫磁分离（IMS）是从大量食品样品中分离和浓缩目标细菌的一种众所周知的方法。用抗体功能化的磁珠可对诸如大肠杆菌的目标细菌提供选择性O157：H7。此外，与常规方法相比，实时PCR可以对目标细菌进行高灵敏度检测。本研究提出的方法包括三个步骤：（1）预富集；（2）自动化IMS和目标细菌的浓缩；（3）通过实时PCR检测目标细菌。使用工作样品体积高达250 mL的食物样品，整个过程仅需要3小时。结果，目标细菌的范围为10 ¹ –10 ²通过使用建议的方法，可以在食品样品（例如牛奶，牛肉末和卷心菜）中检测到每毫克或克样品中的菌落形成单位。我们期望结合实时PCR的自动化IMS系统将有助于开发用于检测食源性细菌的全自动系统，并可以作为多种细菌菌株的多功能检测仪设备在不久的将来。