Bacteriophage significantly reduces Listeria monocytogenes on raw salmon fillet tissue
Posted: January 7th, 2010 - 9:29am
Source: Journal of Food Protection®, Volume 73, Number 1, pp. 32-38(7)
We have demonstrated the antilisterial activity of generally recognized as safe (GRAS) bacteriophage LISTEX P100 (phage P100) on the surface of raw salmon fillet tissue against Listeria monocytogenes serotypes 1/2a and 4b. In a broth model system, phage P100 completely inhibited L. monocytogenes growth at 4°C for 12 days, at 10°C for 8 days, and at 30°C for 4 days, at all three phage concentrations of 104, 106, and 108 PFU/ml. On raw salmon fillet tissue, a higher phage concentration of 108 PFU/g was required to yield 1.8-, 2.5-, and 3.5-log CFU/g reductions of L. monocytogenes from its initial loads of 2, 3, and 4.5 log CFU/g at 4 or 22°C. Over the 10 days of storage at 4°C, L. monocytogenes growth was inhibited by phage P100 on the raw salmon fillet tissue to as low as 0.3 log CFU/g versus normal growth of 2.6 log CFU/g in the absence of phage. Phage P100 remained stable on the raw salmon fillet tissue over a 10-day storage period, with only a marginal loss of 0.6 log PFU/g from an initial phage treatment of 8 log PFU/g. These findings illustrate that the GRAS bacteriophage LISTEX P100 is listericidal on raw salmon fillets and is useful in quantitatively reducing L. monocytogenes.