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Develop new technologies that rapidly identify pathogens.

We know that the faster we are able to identify the existence of bacteria in a product, the more time we have to improve that product's safety profile. USDA-ARS scientists are in the process of developing multi-analyte biosensors that contain multiple members of a drug or chemical family. The sensors may be coupled directly on-line to detect pathogens and residues in foods and feed. The sensors should be useful to regulatory agencies as well as to companies looking to optimize product quality and safety.

The development of adequate sampling protocols is a critical component of any bacteria detection or HACCP program. Researchers intend to develop techniques that result in the separation of pathogens from an aggregate matrix or biofilm, and which simultaneously enrich and concentrate several pathogenic species.

The extraction and concentration processes are essential for a biosensor that does not rely on a pre-enrichment culture step. The scientists are preparing and concentrating pathogens using techniques such as sequential filtration, gravitation, immunotrapping, ligand-receptor interactions and cell sorting. If a pre-enrichment step is necessary, they'll develop processes that shorten the incubation times required.

Such techniques as integrated optical sensing, mass spectrometry, sensitive fluorescence, immunoelectrochemical detection, immunomagnetic electrochemiluminescence, microchip arraying and combinatorial chemistry will be adapted to meet the research goals. Reagents such as monoclonal antibodies, receptors and molecular imprints will be generated to facilitate separation and detection schemes.

You also may want to talk to researchers at the University of Rhode Island, who, along with colleagues at the U.S. Army Soldier Systems Center (Natick, MA), have developed a sensitive and rapid chemiluminescent fiber-optic biosensor. The device uses monoclonal antibodies to detect S. aureus in food.

The system incorporates a microwell plate vacuum filtration unit with an 8-mm membrane sealed at the bottom of the sample well. A sample is concentrated on the membrane and positioned directly in front of a fiber-optic light guide that collects and transmitts the signal to the luminometer. This approach eliminated the antibody immobilization step and allowed cell labeling to occur in solution. The sensitivity of the biosensor is 3.8 x l04 CFU/ml, which was adequate to detect the organism at concentrations lower than the level that could result in food poisoning.

Further information. AT USDA: Larry Stanker, USDA-ARS Western Regional Research Center, 800 Buchanan St., Albany, CA 94710; phone: 510-559-5984; fax: 510-559-6162; email: At the University of Rhode Island: A. Garth Rand, Food Science and Nutrition Research Center, 530 Liberty Lane, West Kingston, RI 02881; phone: 401-874-4081; fax: 401-874-5974;
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Publication:Microbial Update International
Date:Jun 1, 2003
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