LOW-COST BACTERIAL DETECTION SYSTEM FOR FOOD SAFETY BASED ON AUTOMATED DNA EXTRACTION, AMPLIFICATION AND READOUT

Abstract

To ensure food, medical and environmental safety and quality, rapid, low-cost and easy-to-use detection methods are desirable. Here, the LabSystem is introduced for integrated, automated DNA purification and amplification. It consists of a disposable, centrifugally-driven DNA purification platform (LabTube) and the subsequent amplification in a low-cost UV/vis-reader (LabReader). In this paper, food safety was chosen as the first sample application with pathogenic verotoxin-producing (VTEC) Escherichia coli (E.coli) in water and milk, and the product-spoiler Alicyclobacillus acidoterrestris (A acidoterrestris) in apple juice as sample organisms. DNA was amplified qualitatively using isothermal loop-mediated DNA amplification (LAMP) and quantitatively using real-time PCR. By optimizing manual purification protocols inside the LabTube, as little as 45 inserted DNA copies were extracted from E.coli and A.acidoterrestris lysates in real samples (milk, juice and water). To run isothermal DNA amplification (LAMP) and PCR inside the LabReader, temperature control as well as data analysis methods were implemented. Combined detection limits for DNA purification and amplification from bacteria lysates in real samples at 102-103 inserted copies were achieved. The demonstrated LabSystem runs with standard laboratory equipment and reduces hands-on times from 30min to 3min.