Biocontrol of Salmonella Enteritidis in spiked chicken cuts by lytic bacteriophages ΦSP-1 and ΦSP-3

The ability of host specific bacteriophages phi SP-1 and phi SP-3 to lyse Salmonella in artificially contaminated cuts of pressure cooked chicken meat was evaluated at different temperatures -4 degrees C, room temperature (28 +/- 0.5 degrees C) and 37 degrees C applying low and high multiplicity of infection (MOI). Bacteriophages were able to significantly reduce the bacterial counts at all the temperatures studied. At 4 degrees C, individual application of phi SP-1and phi SP-3 resulted in significant drop in bacterial counts (log(10) 2.46 and 2.1CFU/ml, respectively) at high MOI and (log(10) 0.98 and 0.52CFU/ml, respectively) at low MOI, when compared to the untreated control on day 3. Similarly at room temperature the drop was log(10) 3.99 and 3.46CFU/ml at high MOI and log(10) 2.51 and 2.3CFU/ml at low MOI. At 37 degrees C the drop was log(10) 1.98 and 2.38 at high MOI and at low MOI it was log(10)1.52 and 1.98CFU/ml. Increased efficiency was observed when phages where applied as cocktail at high MOI as the bacterial counts at the end of day 3 dropped by log(10) 3.52CFU/ml at 37 degrees C and to beyond detectable level at 4 degrees C and room temperature. The average reduction of bacterial load in the same group was -4 degrees C (79%), room temperature (92%) and 37 degrees C (78%).