The outbreaks of foodborne diseases associated with bacterial contamination are still critical issues all over the world. To ensure food safety, the diagnosis of pathogenic bacteria on site at early state of contamination are required. Escherichia coli O157:H7 (E. Coli O157:H7) is one of the major factor causing foodborne diseases. We introduce a sandwich type colorimetric detection method integrated with chitosan-coated starch magnetic polymer beads(CS@SMBs) that can separate and concentrate bacteria in aqueous environment. For signal amplification, horseradish peroxidase-conjugated antibody (HRP-Antibody) and 3,3',5,5'- tetramethylbenzidine (TMB) were employed as enzyme label and chromogenic substrate, respectively. We demonstrate that CS@SMBs not only show a good magnetic sensitivity, but also can capture a variety of bacteria regardless of Gram-negative and Gram-positive, which offer possibility for separation of the broad range of bacteria from food matrix. Our approach successfully captures E. coli O157:H7 with detection limit of 101 CFU/mL through naked eye, making promise of fast, on-site, and sensitive detection of pathogenic bacteria.

• Sang-Mook You(Graduate School of Biotechnology & Department of Food Science and Biotechnology, Kyung Hee University, Yongin Korea)
• Ke Luo(Graduate School of Biotechnology & Department of Food Science and Biotechnology, Kyung Hee University, Yongin Korea)
• Young-Rok Kim(Graduate School of Biotechnology & Department of Food Science and Biotechnology, Kyung Hee University, Yongin Korea)