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M. B. MEDINA, Eastern Regional Research Center, Agricultural Research Service, U. S. Department of Agriculture, 600 East Mermaid Lane, Wyndmoor, PA 19038

Real-time binding interactions of collagen I, fibronectin, laminin, actin and myosin with Salmonella typhimurium were studied using a surface plasmon resonance (SPR) biosensor. S. typhimurium cells were immobilized on the sensor chip and the proteins were allowed to bind with the bacterial cell surface in a continuous flow system. The bound molecules generated changes in refractive index near the sensor surface and were measured by a photodiode array detector as response units (RU). The results showed that the binding of collagen was greater than myosin, laminin, actin and fibronectin,respectively. The collagen and laminin mixture generated an additive binding response. However, the mixture of actin and myosin resulted in a response lower than actin binding, suggesting the loss of actin-myosin binding epitopes to the cell surface of Salmonella. The binding kinetics of collagen to the cell surface of Salmonella showed an estimated dissociation rate of 3.90E-4/sec and association rate of 1.07E+4/M/sec in 12 replicate analysis. Collagen is a major protein component in animal skins and connective tissues, the vehicle for bacterial attachment. The binding of collagen to Salmonella surface was utilized as a model system to study the inhibitory effects of 15 food grade compounds. These compounds were classified according to percent inhibition as highly active inhibitors (80-100%), medium (50-79%), low (10-49%) and no inhibition (0-9%). The SPR biosensor provided a rapid and effective means to study the interactions of carcass macromolecules such as collagen and the bacteria surface. It also provided us with a model system that can lead to development of new intervention techniques to reduce pathogen contamination of meat and poultry.