Propagation method for persistent high yield of diverse Listeria phages on permissive hosts at refrigeration temperatures

Radford, Devon; Ahmadi, Hanie; León-Velarde, Carlos G.; Balamurugan, S.

doi:10.1016/j.resmic.2016.05.010

Cited by 7 publications

(4 citation statements)

References 28 publications

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“…Listeria phage A511 was obtained from The Félix d’Hérelle Reference Center for Bacterial Viruses, University of Laval (Quebec, QC, Canada). Phage A511 was propagated as described by Radford et al (2016) with some minor modifications. Briefly, 200 μL of L. monocytogenes subculture (10 9 CFU mL -1 ) and 100 μL of phage A511 (10 9 PFU mL -1 ) were added to 4 mL of top agar supplemented with CaCl 2 (TSB, 0.5% agar, 10 mM CaCl 2 ).…”

Section: Methodsmentioning

confidence: 99%

“…After refrigeration all the liquids were extracted using a micropipette and filtered through 0.22 μm membranes. The filtrate was retained and stored at 4°C until use ( Radford et al, 2016 ). The titre of propagated phages was determined by adding serial dilutions to agar overlays and incubating as previously described by Kropinski et al (2009) .…”

Section: Methodsmentioning

confidence: 99%

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Thermal-Stability and Reconstitution Ability of Listeria Phages P100 and A511

et al. 2017

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The study evaluated the thermal-stability of Listeria phages P100 and A511 at temperatures simulating the preparation of ready-to-eat meats. The phage infectivity after heating to 71°C and holding for a minimum of 30 s, before eventually cooling to 4°C were examined. Higher temperatures of 75, 80, and 85°C were also tested to evaluate their effect on phages thermal-stability. This study found that despite minor differences in the amino acid sequences of their structural proteins, the two phages responded differently to high temperatures. P100 activity declined at least 10 log (PFU mL-1) with exposure to 71°C (30 s) and falling below the limit of detection (1 log PFU mL-1) while, A511 dropped from 108 to 105 PFU mL-1. Cooling resulted in partial reconstitution of P100 phage particles to 103 PFU mL-1. Exposure to 75°C (30 s) abolished A511 activity (8 log PFU mL-1) and both phages showed reconstitution during cooling phase after exposure to 75°C. P100 exhibited reconstitution after treatment at 80°C (30 s), conversely A511 showed no reconstitution activity. Heating P100 to 85°C abolished the reconstitution potential. Substantial differences were found in thermal-stability and reconstitution of the examined phages showing A511 to be more thermo-stable than P100, while P100 exhibited reconstitution during cooling after treatment at 80°C which was absent in A511. The differences in predicted melting temperatures of structural proteins of P100 and A511 were consistent with the observed differences in thermal stability and morphological changes observed with transmission electron microscopy.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Thermal-Stability and Reconstitution Ability of Listeria Phages P100 and A511

et al. 2017

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“…This has also been observed for a number of other foodborne pathogens and their phages in food system experiments (O'Flynn et al, 2004;Hong et al, 2016). In the O'Flynn et al (2004) study, the authors noted that significant reductions in E. coli cell numbers were obtained at 30 and 37 • C; however, the lytic ability of the phage cocktail was greatly reduced at 12 • C. Radford et al (2016) described the efficient production of a high concentration of Listeria phage under refrigeration conditions, a method that may be adapted to optimize the application of phages as a biocontrol on food matrices in future experiments (Radford et al, 2016).…”

Section: When Stored Atmentioning

confidence: 71%

Isolation and Characterization of Listeria monocytogenes Phage vB_LmoH_P61, a Phage With Biocontrol Potential on Different Food Matrices

Stone

Lhomet

Neve

et al. 2020

Front. Sustain. Food Syst.

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The high mortality rate associated with Listeria monocytogenes as well as its ability to adapt to the harsh conditions employed in food processing have ensured that this pathogen has become a significant concern in the ready-to-eat food industry. Lytic bacteriophages are viruses that hijack the metabolic mechanisms of their bacterial host as a means to grow and replicate, subsequently leading to host cell death due to lysis. This study reports the biological and genomic characterization of L. monocytogenes phage vB_LmoH_P61 (P61) and its potential application for the reduction of L. monocytogenes in artificially contaminated foods. Phage P61 is a virulent bacteriophage belonging to the family Herelleviridae and has a genome size of 136,485bp. The lytic spectrum of phage P61 was investigated and it was shown to infect serotypes 1/2a, 1/2b, 1/2c, 4b, 4e, and 6a. Treatment of artificially contaminated milk stored at 8 and 12 • C with phage P61 resulted in a significant reduction in L. monocytogenes numbers over the product shelf life. Similarly, phage P61 reduced L. monocytogenes numbers on artificially contaminated baby spinach stored at 8, 12, and 25 • C. The research findings indicate that biocontrol of L. monocytogenes with phage P61 may offer a safe and environmentally friendly approach for the reduction of L. monocytogenes numbers in certain ready-to-eat foods.

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“…Listeria bacteriophage A511 ( Klumpp et al, 2008 ) was obtained from The Félix d’Hérelle Reference Center for Bacterial Viruses, University of Laval (Quebec, QC, Canada) and propagated using L. monocytogenes ATCC 19115 as the host (recommended by The Félix d’Hérelle Reference Center for Bacterial Viruses) utilizing the method described by Radford et al (2016) with some minor modifications. Briefly, 200 μL of L. monocytogenes (ATCC 19115) subculture (10 9 CFU/mL) was added to 4 mL of top agar supplemented with CaCl 2 (TSB, 0.5% agar, 10 mM CaCl 2 ).…”

Section: Methodsmentioning

confidence: 99%

Examination of the Use of Bacteriophage as an Additive and Determining Its Best Application Method to Control Listeria monocytogenes in a Cooked-Meat Model System

et al. 2020

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The study examined the efficacy of using bacteriophage as an additive in a cookedmeat model system to control growth of contaminating Listeria monocytogenes during subsequent storage. Studies were designed where Listeria bacteriophage A511 and L. monocytogenes introduced inside or on the surface of the cooked-meat to simulate different bacteriophage application and pathogen contamination scenarios. These scenarios include: (1) A511 and L. monocytogenes in meat; (2) A511 in meat, L. monocytogenes on surface; (3) L. monocytogenes in meat, A511 on surface; and (4) L. monocytogenes followed by A511 on meat surface. Real world bacteriophage application and pathogen contamination levels of 10 9 PFU/g and 10 3−4 CFU/g, respectively, were used. These meats were then vacuum packaged and stored at 4 • C and changes in A511 titers and L. monocytogenes numbers were enumerated during the 28-day storage. Under the conditions tested, application of A511 directly on top of L. monocytogenes contaminating the surface of the meat was the only scenario where L. monocytogenes numbers were reduced to below detection limits and remained significantly lower than the controls for up to 20 days. Although A511 titers remained stable when applied as an additive in meat, they were not successful in controlling growth of the contaminating L. monocytogenes (present inside or on surface of meat). Similarly, application of A511 on the surface of the meat could not control growth of L. monocytogenes present inside the meat. L. monocytogenes numbers increased from the initial 3-log CFU/g to 9-log CFU/g similar to the controls by the end of the 28-day storage. These results suggest that bacteriophages are effective in controlling growth of surface contaminating bacteria only when applied directly onto the surface of the contaminated food product, and are ineffective as a biocontrol agent when used as an additive.

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Propagation method for persistent high yield of diverse Listeria phages on permissive hosts at refrigeration temperatures

Cited by 7 publications

References 28 publications

Thermal-Stability and Reconstitution Ability of Listeria Phages P100 and A511

Thermal-Stability and Reconstitution Ability of Listeria Phages P100 and A511

Isolation and Characterization of Listeria monocytogenes Phage vB_LmoH_P61, a Phage With Biocontrol Potential on Different Food Matrices

Examination of the Use of Bacteriophage as an Additive and Determining Its Best Application Method to Control Listeria monocytogenes in a Cooked-Meat Model System

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