Characterization of the narrow-spectrum bacteriophage LSE7621 towards Salmonella Enteritidis and its biocontrol potential on lettuce and tofu

As the natural antibacterial agents, bacteriophages have great potential for controlling food pathogens. Compared to broad-spectrum bacteriophages, narrow-spectrum bacteriophages can reduce the risk of developing community-wide resistance and have little impact on microbial flora. The present study aimed to isolate and characterize a narrow-spectrum bacteriophage that effectively controlled Salmonella enterica serovar Enteritidis (Salmonella Enteritidis) in food. A narrow-spectrum bacteriophage LSE7621, which can effectively lyse Salmonella Enteritidis, was obtained from sewage by the double-layer agar plate method. LSE7621, which belonged to the order Caudovirales and family Myoviridae, showed good pH tolerance (pH 4.0-11.0) and thermal stability (30-50 degrees C). LSE7621 was able to significantly and effectively control Salmonella on lettuce and tofu (p < 0.05). When LSE7621 was administered on lettuce, the number of Salmonella was reduced by 0.86 log(10) CFU/mL (MOI = 100) and 1.02 log(10) CFU/mL (MOI = 1) within 6 h. When LSE7621 was administered on tofu, the number of Salmonella decreased by 3.55 log(10) CFU/mL (MOI = 100) and 1.86 log(10) CFU/mL (MOI = 1) within 4 h. This is the first report about narrow-spectrum bacteriophage infecting Salmonella Enteritidis. This study provides insights into fundamental researches on narrow-spectrum bacteriophage and facilitates the utilization of new bacteriophage resource.