Characterization and application of novel bacteriophage PS2 for controlling pathogenic Escherichia coli in different food matrices

초록

This study was aimed to investigate a novel Escherichia phage, vB_EcoS_PS2, which was isolated from sewage and identified as a member of the Dhillonvirus genus within the Caudoviricetes class based on its isometric head and long, non-contractile tail morphology. Whole-genome analysis confirmed the absence of genes associated with antibiotic resistance, lysogeny, and virulence factors in its 44,264 bp genome. Phage PS2 exhibited high specificity against E. coli strains at various serotypes, including O157:H7, O6, and O78:K80:H12. The biological property showed that phage PS2 had a short latent period (20 min) and large burst size (410 PFU/cell), and maintained stability when exposed to a broad range of temperatures (4-60 degrees C) and pH levels (4-10). In broth, phage PS2 effectively inhibited bacterial growth and delayed regrowth for up to 20 h. Additionally, phage PS2 effectively eradicated preformed biofilms, achieving a 4.8 log reduction in viable cell counts. Phage PS2 was evaluated for its biocontrol efficacy in milk, rice gruel, and packaged pork sausage at 4 degrees C and 25 degrees C. At higher MOIs, it significantly reduced bacterial populations, achieving up to 6.20 log reduction in milk, 5.94 log in rice gruel, and 5.26 log in sausage, showing its effective biocontrol potential. Compared to the control, phage PS2 treatment significantly reduced pathogenic E. coli populations with sustained inhibition across all tested food models. The solid food model showed varying efficacy depending on the MOI, highlighting the need for optimized application strategies in complex food matrices. To conclude, Escherichia phage PS2 exhibited excellent stability, strong lytic activity, and broad efficacy against various E. coli serotypes, establishing it as a promising biocontrol agent for enhancing food safety.

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