Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
8843459 | Food Microbiology | 2018 | 9 Pages |
Abstract
Phages are potentially useful as antimicrobial agents in food, especially cocktails of different phages which may prevent the development of bacterial resistance. Biocontrol assays with a six-phage cocktail, which is lytic against DH5α, an enteropathogenic (EPEC) and two Shiga-toxigenic (STEC) Escherichia coli strains, were performed in Hershey-Mg broth, milk and meat at refrigerated (4â¯Â°C), room (24â¯Â°C) and abusive (37â¯Â°C) temperatures. At 4â¯Â°C, cell counts were significantly lower (2.2-2.8 log10â¯CFU/mL) when E. coli strains (â¼109â¯CFU/mL) were challenged against the phage cocktail (â¼109â¯PFU/mL) in Hershey-Mg broth after 24â¯h. However, reductions were higher (3.2-3.4 log10â¯CFU/mL) after a 48â¯h exposure for all the strains tested. In addition, reduction values reached up to 3.4 log10â¯CFU/mL (24â¯Â°C) and 3.6 log10â¯CFU/mL (37â¯Â°C) in challenge tests after 24â¯h, though the reductions achieved were slightly lower after 48â¯h for the four E. coli strains tested. In milk, the cocktail was highly effective since bacterial counts were below the detection limit (<101â¯CFU/mL) at 4â¯Â°C, while the reductions ranged from 2 to 4 log10â¯CFU/mL at 24â¯Â°C after a 24â¯h exposure. At 37â¯Â°C, DH5α was eliminated within 2â¯h, and an average cell decrease of 4 log10â¯CFU/mL was observed for the three pathogenic strains tested. When the assays were performed in meat, biocontrol values ranged from 0.5 to 1.0 log10â¯CFU/mL after 48â¯hâ¯at 4â¯Â°C, while a higher cell inactivation was achieved at 24â¯Â°C (2.6-4.0 log10â¯CFU/mL) and 37â¯Â°C (3.0-3.8 log10â¯CFU/mL). Furthermore, higher inactivation values for O157:H7 STEC (1.55â¯Â±â¯0.35 log10â¯CFU/mL) at 4â¯Â°C were obtained in meat when incubation was extended up to 6 days. As a conclusion, our six-phage cocktail was highly effective at 24â¯Â°C and 37â¯Â°C, though less effective at 4â¯Â°C in both food matrices evaluated. Thus, it might be applied against pathogenic EPEC and STEC strains to prevent foodborne diseases especially when the cold chain is lost.
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Authors
David Tomat, Cecilia Casabonne, Virginia Aquili, Claudia Balagué, Andrea Quiberoni,