In‐milk inactivation of <scp><i>Escherichia coli</i></scp> O157:H7 by the environmental lytic bacteriophage ECPS‐6

Abstract

Abstract Shiga toxin‐producing Escherichia coli is a common foodborne pathogen which transmission includes dairy products. In the search for novel biocontrol methods, bacteriophages have become important candidates for the eradication of foodborne pathogens. The aim of this study was to evaluate the bacteriophage‐mediated reduction of E . coli O157:H7 in raw and filtered milk. Laboratory‐scale tests showed that the bacteriophage ECPS‐6 efficiently adsorbed to E . coli O157: H7 cells. Furthermore, ECPS‐6 remained stable when heated at 70°C for 20 min and in a wide pH range from 3.0 to 11.0. The trials on contaminated milk were performed using filtered and unfiltered raw milk contaminated with 1 × 10 5 CFU × ml −1 of E . coli O157: H7. Bacteriophage was added at multiplicity of infection (MOI) 5 and 50. The ECPS‐6 reached the highest lytic activity at MOI = 5 (25°C) which resulted in 4.74 Log 10 CFU × ml −1 and 7.3 Log 10 CFU × ml −1 reduction after 10 days for both tested strains, respectively. Under refrigerated conditions (4°C) the quantity of E . coli decreased to 1.5 Log 10 CFU × ml −1 and 3.04 Log 10 CFU × ml −1 for these strains, respectively. Usage of MOI = 50 for the treatment unfiltered milk led to the reduction of E . coli O157:H7 A‐2 below the detection limit after 6 hr.