Isolation, characterization and application of an alkaline resistant virulent bacteriophage JN01 against Escherichia coli O157:H7 in milk and beef

Bacteriophage is a new biological control tool for the prevention and treatment of foodborne pathogens. In this study, an alkali-resistant phage against Escherichia coli (E. coli), named JN01, was isolated and characterized from wastewater. It exhibited lytic activities against 16 of 20 E. coli strains, 11 of which were more than three multidrug resistant strains. The biological characteristics of JN01 showed that the latent period and lysis period was 15 min and 85 min, respectively. The burst size of JN01 was about 134 PFU per infected cell. JN01 was relatively stable under stressed conditions such as temperatures (30 degrees C-70 degrees C) and pH (4-13). The genome of JN01 is 88,360-bp double-stranded DNA molecules, with a total of 130 open reading frames (ORFs) and 38.76% of G + C content. Importantly, no known virulence-associated, antibiotic and lysogeny-related genes were identified in the genome of JN01. Morphological and phylogenetic analyses confirmed that JN01 belongs to the Myoviridae. Viable cell counts of E. coli O157: H7 were reduced in milk and raw beef samples when treated with JN01 at 4 degrees C. The results indicated that JN01 could be a natural potential biological control agent for E. coli O157: H7 in foods.