Microbial Antagonists of Escherichia coli O157:H7 on Fresh-Cut Lettuce and Spinach

Fresh-cut lettuce and spinach can become contaminated with pathogens at numerous points from the field to the retail market. Natural microflora present off fresh produce may hell) reduce the pathogen load. The objective of this Study was to isolate natural microflora front fresh-cut iceberg lettuce and baby spinach and to determine whether these bacteria were antagonistic toward Escherichia coli H157:O7. Samples were collected under conditions that mimicked actual practices between production and retail sale. Evidence of naturally Occurring microorganisms on fresh lettuce (295 isolates) and spinach (200 isolates) and of possible antagonistic activity toward E. coli O157:H7 was documented. Inhibitory activity by several isolates was due to either acid production or antimicrobial peptides. Bacteria with inhibitory activity were isolated from every step in the processing and handling of the fresh-cut iceberg lettuce and baby spinach.