The primary objective of this multi-year project is to create biosensors that are capable of detecting the presence of various toxins and pathogenic bacteria in food products. In the long term, we are seeking to develop miniaturized bacterial sensors capable of being incorporated into a stamp-sized device and combined with RFID for the monitoring of bulk food shipments; to investigate the sensitivity and specificity of the prototype microchip sensors using model biological toxins, living pathogens, and spores; to determine the longevity/stability/specifications of these sensors in a food product environment; to develop miniaturized electronics for the RFID sensor tag devices; and to test the RFID sensor tag devices in the field.
NON-TECHNICAL SUMMARY: Ensuring the safety of our food supply from naturally occurring or deliberate acts of contamination is a national priority that affects all citizens of the United States. Every year, as many as 76 million Americans become ill due to food-borne pathogens, representing an estimated $30 billion in lost productivity. Recent incidents involving large-scale accidental contaminations and difficulties in tracing/recovering tainted food products indicate the need for "new technologies" to ensure the safety of our food. The principal impediments to identification and removal of unsafe food include the lack of rapid food pathogen detection methods, a cumbersome inventory-traceability system, and the inability to identify the source of the problem requiring correction. The development of new methodologies that can rapidly detect the presence of toxins and pathogenic bacteria in food products and trace the tainted food back to its origin must be a part of any comprehensive strategy to lower the incidence of food-borne illness. Current industrial methods of detecting pathogenic bacteria require a minimum of six to 48 hours, by which time portions of the food may have been distributed, marketed, sold, and/or eaten before a problem is even detected. Rapid, specific, and sensitive methods of detecting the presence of food-borne pathogens are required to improve the safety of our food. This research project is part of a strategic plan to develop sensor tags for the detection of food-borne bacteria such as Salmonella typhimurium. These sensor tags would be placed on every food product sold in the United States, enabling monitoring for the presence of toxins and pathogenic bacteria, food spoilage, and product time and temperature; and instantaneous traceability. In response to recent concerns of agro-terrorism, this research is pursuing the development of detection technologies that can be used to rapidly identify deliberate contamination of foods with bio-threat agents such as anthrax, Salmonella, and ricin. New phage-based detection technologies with anticipated detection limits several orders of magnitude better and shelf-lives up to five times longer are being investigated. The long-range goal is to incorporate these sensors as part of the sensor tags to enable quick detection of agro-terrorism attacks. <P>APPROACH: In order to accomplish these objectives, a series of simultaneous, coordinated research projects will be conducted under four task sets, A through D. <br><br>Task A: Biomolecular Recognition Elements: expand the phage libraries for Bacillus anthracis phage and Salmonella typhimurium phage by incorporating rare codons; this procedure will lead to landscape phage libraries with a maximum diversity of displayed oligopeptides; genetically engineer phage to fuse affinity tags (His-tag and/or Strep-tag) to Protein IX to facilitate uniform phage attachment to the biosensor surface; and construct new landscape phage libraries and select phage probes specific to antibiotic resistant virulent strains of Staphylococcus aureus. <br><br>Task B: Sensor Platform Development: reduce size of magnetoelastic sensor platform to lengths of 50 microns; and redesign fabrication process to reduce residual stress and corrosion and improve resonance signal of sensor platform. <br><br>Task C: Biosensor Testing: characterize performance of magnetoelastic sensors in the simultaneous detection of spores and bacteria; demonstrate RNA sensor for the detection of Salmonella typhimurium; construct and demonstrate FET-based DNA biosensor for the detection of Salmonella typhimurium. <br><br>Task D: Food Sample Preparation and Delivery: fabricate and demonstrate microfluidic chip capable of delivering one to 10 target species for demonstration of single spore/bacteria magnetoelastic biosensor detection; and investigate aerosol techniques for sampling spores in dry food products.