Biocontrol of Escherichia coli O157:H7 in ready-to-eat salad using a lytic bacteriophage

Abstract

E. coli O157:H7 is a life threatening foodborne pathogen associated with thousands of infections. Controlling such bacterial pathogens in raw and ready-to-eat foods has gained urgency with each passing day. The use of specific virulent bacteriophages as a biocontrol agent on minimally processed foods is an effective, natural and non-destructive treatment. This study was aimed at determining the efficiency of a lytic bacteriophage against E. coli O157:H7 in ready-to-eat salads. For this purpose, E. coli O157:H7 NCTC 12900 (EC00) and nalidixic acid resistant E. coli O157:H7 ATCC 43895 (NA-EC95) were used as the model bacterium in decontamination trials of mayonnaise based ready-to-eat salads which are consumed without any heating process and include beans, carrots, potatoes, pickled cucumbers and salami. A previously described phage M8AEC16 which was classified in Myoviridae family was used as the biocontrol agent. The highest reductions were observed at 22 degrees C storage conditions. Reductions reaching up to 2.7 log cfu/g of viable E. coli O157:H7 counts were observed in the beginning of the storage period. The findings of the study showed that phage M8AEC16 can be used as a biocontrol agent in the decontamination of E. coli O157:H7 in such mayonnaise based ready-to-eat salads.