title: Host range and in vitro lysis of Listeria monocytogenes seafood isolates by bacteriophages.
abstract: Listeria-infecting bacteriophages (listeriaphages) can be used to control Listeria monocytogenes in the food industry. However, the sensitivity of many of seafood-borne Listeria strains to phages has not been reported. This research investigated the host ranges of three listeriaphages (FWLLm1, FWLLm3 and FWLLm5) by the formation of lytic zones and plaques on host lawns and in vitro lysis kinetics of listeriaphage FWLLm3. The study also predicted the phage titres required to lyse host cells. The host ranges of the phages were determined using 50 L. monocytogenes strains, of which 48 were isolated from the seafood industry and two from clinical cases. Of the 50 strains, 36 were tested at 25 and 30 ℃ and the remainder (14) at 15 and 25 ℃. Based on the formation of either discrete plaques or lytic zones (host kill zones), the host ranges of FWLLm1, FWLLm3 and FWLLm5 were about 87%, 81% and 87%, respectively, at 25 ℃. Six L. monocytogenes strains from the seafood environment were insensitive to all three phages, while the other seafood strains (42) were phage-sensitive. The adsorption rate constant (k value) of listeriaphage FWLLm3 was between 1.2 × 10(-9) and 1.6 × 10(-9 )ml/min across four host strains in tryptic soy broth at 25 ℃. The cultures (at 3-4 log colony-forming unit (CFU/ml) were completely lysed (<1 log CFU/ml) when cultures were infected with FWLLm3 at > 8.7 log phage-forming units (PFU/ml) for 30 min. Re-growth of phage-infected cultures was not detected after 24 h. The effective empirical phage titre was similar to the calculated titre using a kinetic model. Results indicate the potential use of the three phages for controlling L. monocytogenes strains in seafood processing environments.
authors.affiliation: Institute of Food, Nutrition and Human Health, Massey University, Albany Campus, North Shore City, Auckland, New Zealand.
authors.forename: Geevika J Ganegama
authors.initials: GJ
authors.lastname: Arachchi
authors.affiliation: The New Zealand Institute for Plant & Food Research (PFR) Limited, Mt Albert, Auckland, New Zealand.
authors.forename: Cristina D
authors.initials: CD
authors.lastname: Cruz
authors.affiliation: Food Standards Australia New Zealand (FSANZ), Barton, Canberra BC, Australia.
authors.forename: Beatrice M
authors.initials: BM
authors.lastname: Dias-Wanigasekera
authors.affiliation: Department of Food Science and Agri-Food Supply Chain Management, Harper Adams University, Edgmond, Newport, Shropshire, United Kingdom.
authors.forename: Lynn
authors.initials: L
authors.lastname: McIntyre
authors.affiliation: Food Programme, Institute of Environmental Science and Research (ESR) Limited, Christchurch Science Centre (CSC), Ilam, Christchurch, New Zealand.
authors.forename: Craig
authors.initials: C
authors.lastname: Billington
authors.affiliation: Food Programme, Institute of Environmental Science and Research (ESR) Limited, Christchurch Science Centre (CSC), Ilam, Christchurch, New Zealand.
authors.forename: Andrew
authors.initials: A
authors.lastname: Hudson
authors.affiliation: Institute of Food, Nutrition and Human Health, Massey University, Albany Campus, North Shore City, Auckland, New Zealand.
authors.forename: Steve H
authors.initials: SH
authors.lastname: Flint
authors.affiliation: Institute of Food, Nutrition and Human Health, Massey University, Albany Campus, North Shore City, Auckland, New Zealand A.N.Mutukumira@massey.ac.nz.
authors.forename: Anthony N
authors.initials: AN
authors.lastname: Mutukumira
mesh_terms: D000818:Animals; D001435:Bacteriophages / Q000145:classification* / Q000502:physiology*; D058507:Host Specificity; D054884:Host-Pathogen Interactions; D008089:Listeria monocytogenes / Q000145:classification* / Q000302:isolation & purification / Q000821:virology*; D017747:Seafood / Q000382:microbiology*
keywords: Host range; Listeria monocytogenes; adsorption rate constant; listeriaphages; seafood