Application of bacteriocins from Enterococcus hirae on butterhead lettuce seeds inoculated with Escherichia coli O157:H7

Abstract

Several outbreaks of Escherichia coli O157:H7 infections have been associated with contaminated seeds and sprouts. Effective procedures to control pathogenic bacteria on seeds destined for sprout production should be developed to ensure an acceptable microbiological quality. In this study, the use of bacteriocins produced by Enterococcus hirae (Eh9) was analyzed as a potential method to control the endogenous microbial populations of lettuce seeds and avoid pathogen contamination on seeds destined for sprout production. Seeds decontamination with Eh9 cell-free supernatant (CFS) achieved a significative fungiostatic effect without affecting germination. CFS treatment did not exert a biocontrol effect on E. coli endogenous; however, a significant bacteriocin biocontrol was reached on lettuce seeds inoculated with exogenous E. coli during refrigerated storage (7 days). Germination percentage and potential yield were not affected by the treatments. A better understanding of the behavior of pathogens in preharvest environments will assure the delivery of safe produce to the consumer.