Binding of collagen I to Escherichia coli O157:H7 and inhibition by carrageenans

Research at USDA attempts to eliminate or reduce Escherichia coli contamination in meat and poultry foods by understanding the attachment mechanisms. This study utilizes a surface plasmon resonance (SPR) biosensor to determine the interactions of the immobilized E. coli O157:H7 surface with collagen I and selected polysaccharides. The binding and dissociation kinetics of collagen I with E. coli surface molecules had a mean affinity constant (K) of 3×108 (M−1) while the dissociation rate was 4.4×10−5 (s−1). Using the SPR biosensor, carrageenan, sodium alginate and pectin were evaluated for their interactions with collagen I and the E. coli surface. Results showed 89% to 100% inhibition by carrageenans and about 50% by sodium alginate and less than 10% by pectin. The biosensor binding studies were augmented by the scanning electron microscopy studies, which also showed the attachment of E. coli to the collagen fibrils of the bovine tissues. These studies serve as the basis for developing new strategies to block bacterial attachment or detach pathogens from animal carcasses.