A versatile-deployable bacterial detection system for food

The MIT Faculty has made this article openly available. Please share how this access benefits you. Your story matters. Contamination of foods is a public health hazard that episodically causes thousands of deaths and sickens millions worldwide. T o ensure food safety and quality, rapid, low-cost and easy-to-use detection methods are desirable. Here, the LabSystem is introduced for integrated, automated DNA purification, 10 amplification and detection. It consists of a disposable, centrifugally-driven DNA purification platform (LabT ube) and the subsequent amplification and detection in a low-cost UV/vis-reader (LabReader). For demonstration of the LabSystem in the context of food safety, purification of Escherichia coli (non-pathogenic E. coli and pathogenic verotoxin-producing E. coli (VT EC)) in water and milk, and the product-spoiler Alicyclobacillus acidoterrestris (A. acidoterrestris) in apple juice was integrated and 15 optimized in the LabT ube. Inside the LabReader, the purified DNA was amplified, readout and analyzed using both qualitative isothermal loop-mediated DNA amplification (LAMP) and quantitative real-time PCR. For the LAMP-LabSystem, the combined detection limits for purification and amplification of externally lysed VT EC and A. acidoterrestris is 10 2-10 3 cell-equivalents. In the PCR-LabSystem for E. coli cells, the quantification limit is 10 2 cell-equivalents including LabT ube-integrated lysis. T he 20 demonstrated LabSystem only requires a laboratory centrifuge (to operate the disposable, fully closed LabT ube) and the low-cost LabReader for DNA amplification, readout and analysis. Compared with commercial DNA amplification devices, the LabReader improves sensitivity and specificity by the simultaneous readout of four wavelengths and the continuous readout during temperature cycling. T he use of a detachable eluate tube as an interface affords semi-automation of the LabSystem, which does not 25 require specialized training. It reduces hands-on time from about 50 to 3 min with only two handling steps: sample input and transfer of the detachable detection tube.