Our results indicate that STEC bacteriophage mixtures can control some of the six Shiga-toxigenic E. coli on lettuce. The phage cocktail is very effective on lettuce against E. coli O157:H7, O145, and O26, serogroups that are frequently associated with foodborne outbreaks in produce. This phage intervention has the potential to be adopted by industry in order to decrease the foodborne risks associated with fresh produce. A very interesting finding was that these particular phages are more effective at refrigerated temperatures. It is normally reported that bacteriophages are more effective at 25 and 37 degrees Celsius—it has been pointed out as a disadvantage for phages to be used in refrigerated food. Another disadvantage is that phages could potentially carry virulence or antibiotic resistance genes. Therefore, it is necessary to assure that phages intended for use in foods are not carrying undesirable genes through whole genome sequencing. This is the process used to determine the complete DNA sequence (all of the genes) of an organism’s genome.
Explore this issueAugust/September 2017
Another issue is the development of resistance; however, this problem can be overcome when multiple phages are used in a mixture, as it overwhelms the bacteria with multiple phage attacks. This intervention can be used during lettuce washing and/or packaging steps without altering the flavor, color, or aroma of fresh produce.
Dr. Narvaez-Bravo is the assistant professor at the University of Manitoba, Food Science Department.
She has more than 10 years of experience working on research within the area of microbiology and food safety. Reach her at Claudia.firstname.lastname@example.org. Dr. McAllister is principal research scientist with Agriculture and Agri-Food Canada, Lethbridge Research Centre, Lethbridge, Alberta, and has been with the organization for the past 25 years. Reach him at Tim.email@example.com.