Isolation,identification and antibacterial effect study of E.coli lytic bacteriophage vB_EcoM_JN03
[Objective]E.coli O157:H7 is one of important foodborne pathogens.The improper use of antibiotics has led to E.coli O157:H7 multi-drug resistance and pan-drug resistance becoming an increasingly serious problem.The study of its natural bactericide,virulent phage,has theoretical significance and practical application value for the prevention and control of E.coli O157:H7 pollution.[Method]In this study,the multi-drug resistant E.coli O157:H7 was used as the host bacteria,and the virulent phage was isolated from sewage by double-layer agar plate method.Its biological characteristics were characterized and the whole genome sequence was analyzed.The antibacterial effect of the phage on E.coli O157:H7 in food was evaluated.[Result]A phage capable of lysing E.coli O157:H7 was successfully isolated and purified,named vB_EcoM_JN03(GenBank accession number:OR885871).vB_EcoM_JN03 belongs to Caudovirales,Myoviridae.The optimal multiplicity of infection(MOI)was 0.01,the incubation period was 30 min,and it reached the plateau after 120 min.The burst size was 80 PFU/cell.It is stable in the range of 30-60℃ and pH 4-12.The genome of bacteriophage vB_EcoM_JN03 is double-stranded DNA,with a total length of 158142 bp,G+C content of 44.63%,encoding 206 open reading frame(ORF),and does not contain known encoded virulence,antibiotic resistance and lysogenic genes.vB_EcoM_JN03 significantly inhibited E.coli O157:H7 in milk and beef samples at 4℃.[Conclusion]In this study,a virulent bacteriophage vB_EcoM_JN03 of E.coli O157:H7 was isolated and identified.It has good inhibitory effect on host bacteria and is expected to be used as a natural bactericide to control E.coli O157:H7 contaminated food.
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