99A-25 |
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M. KIM1, R. A. Durst2, R. A. Montagna3, W. J. Kim1, and W.-S. Shin4. (1) Food Safety Research Team, Korea Food Research Institute, San 46-1, Backhyun-Dong, Sungnam-Si, 463-746, South Korea, (2) Food Science & Technology, Cornell Univ., New York State Agricultural Experiment Station, 630 W. North St., Geneva, NY 14456-1371, (3) Innovative Biotechnologies International, Inc., Grand Island, NY 14072, (4) Food safty research team, Korea Food Research Institute, San 46-1 Baekhyeon-Dong Bundang-Gu, Songnam-Si Kyonggi-Do, 463-420, South Korea The objective of this study is to develop a novel immunochemical technique for the detection of Escherichia coli serotype O157, using immunomagnetic separation (IMS) and liposome immunoassay (LIA) detection. Commercially available immunomagnetic beads with antibodies against E.coli O157 covalently bound to the surface of beads were used for selective separation/concentration of the pathogen. Liposomes encapsulating a fluorescent dye, sulforhodamine B, as a detection marker were chemically modified to have anti-E. coli O157 antibodies conjugated to their surface. One cfu of E.coli O157:H7 spiked into 25 grams of ground beef could be detected after 9 hrs of enrichment culture, followed by 90 min for the IMS-LIA processing. For ground beef spiked with 650 cfu of E.coli O157:H7, 6 hrs of enrichment culture was sufficient to obtain a positive signal by IMS-LIA. The serotypes of E.coli O157:NM which produce Shiga toxin 1 or 2 could be detected by IMS-LIA, but other serotypes such as E.coli O91:H21 and E.coli O32:K:H19, exhibiting different antigenic properties from O157, were not detected. The IMS-LIA technique developed in this work has great potential in assays for E.coli serotype O157 in food by improving speed and sensitivity.
Session 99A, Biotechnology: General
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