title: Biocontrol of Listeria monocytogenes on fresh-cut produce by treatment with lytic bacteriophages and a bacteriocin.
abstract: The fresh-cut produce industry has been the fastest-growing portion of the food retail market during the past 10 years, providing consumers with convenient and nutritious food. However, fresh-cut fruits and vegetables raise food safety concerns, because exposed tissue may be colonized more easily by pathogenic bacteria than intact produce. This is due to the higher availability of nutrients on cut surfaces and the greater potential for contamination because of the increased amount of handling. We found that applied Listeria monocytogenes populations survived and increased only slightly on fresh-cut Red Delicious apples stored at 10 degrees C but increased significantly on fresh-cut honeydew melons stored at 10 degrees C over 7 days. In addition, we examined the effect of lytic, L. monocytogenes-specific phages via two phage application methods, spraying and pipetting, on L. monocytogenes populations in artificially contaminated fresh-cut melons and apples. The phage mixture reduced L. monocytogenes populations by 2.0 to 4.6 log units over the control on honeydew melons. On apples, the reduction was below 0.4 log units. In combination with nisin (a bacteriocin), the phage mixture reduced L. monocytogenes populations by up to 5.7 log units on honeydew melon slices and by up to 2.3 log units on apple slices compared to the control. Nisin alone reduced L. monocytogenes populations by up to 3.2 log units on honeydew melon slices and by up to 2.0 log units on apple slices compared to the control. The phage titer was stable on melon slices, but declined rapidly on apple slices. The spray application of the phage and phage plus nisin reduced the bacterial numbers at least as much as the pipette application. The effectiveness of the phage treatment also depended on the initial concentration of L. monocytogenes.
authors.affiliation: Produce Quality and Safety Laboratory. Henry A. Wallace Beltsville Agricultural Research Center, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, Maryland 20705, USA. leverenb@ba.ars.usda.gov
authors.forename: Britta
authors.initials: B
authors.lastname: Leverentz
authors.forename: William S
authors.initials: WS
authors.lastname: Conway
authors.forename: Mary J
authors.initials: MJ
authors.lastname: Camp
authors.forename: Wojciech J
authors.initials: WJ
authors.lastname: Janisiewicz
authors.forename: Tamuna
authors.initials: T
authors.lastname: Abuladze
authors.forename: Ming
authors.initials: M
authors.lastname: Yang
authors.forename: Robert
authors.initials: R
authors.lastname: Saftner
authors.forename: Alexander
authors.initials: A
authors.lastname: Sulakvelidze
mesh_terms: D001435:Bacteriophages / Q000502:physiology*; D005511:Food Handling; D005519:Food Preservation / Q000379:methods*; D005638:Fruit / Q000382:microbiology*; D006863:Hydrogen-Ion Concentration; D008089:Listeria monocytogenes / Q000187:drug effects / Q000254:growth & development*; D009561:Nisin / Q000494:pharmacology*
chemical_list: D009561:Nisin