Biocontrol of Multidrug-Resistant <i>Enterobacter hormaechei</i> in Meat Products Using Novel Lytic Bacteriophages: Characterization and Genomic Analysis

Multidrug resistance in foodborne pathogens poses a critical threat to food safety and public health. <i>Enterobacter hormaechei</i> is an emerging pathogen with wide environmental prevalence and is capable of causing severe infections. Bacteriophage-based intervention has gained significant recognition as a sustainable approach to combat foodborne pathogens and address antimicrobial resistance in food production systems. Despite this, research on <i>E. hormaechei</i>-specific phages is facing substantial challenges, primarily due to insufficient phage collections and inadequate genomic characterization of existing isolates. In this work, two novel virulent phages (Ehp-YZU-L3 and Ehp-YZU-L4) were isolated from wastewater samples in Yangzhou. Their morphological, biological, and genomic features were characterized. The two phages belonged to the <i>Myoviridae</i> family, with a latency period (10 and 40 min) and high burst size (192 and 292 plaque-forming unit [PFU]/host cell), and an optimal multiplicity of infection of 0.01. The complete genomic sequences of phages ranged from 163,779 to 170,652 bp and GC content of 39.8 - 40.2%, which consisted of 296 and 275 open reading frames of phage Ehp-YZU-L3 and Ehp-YZU-L4. The absence of both virulence-related genetic elements, antimicrobial resistance, and lysogeny-related genes in two genomes was confirmed. Two phages exhibited strong inhibitory effects against <i>E. hormaechei</i> in pork by a phage-dosage-dependent way, with a reduction range of bacterial counts by 1.73-2.87 Log CFU/g for Ehp-YZU-L3 and 1.96-3.20 log CFU/g for Ehp-YZU-L4 at 37°C for 4 h. These findings demonstrate considerable potential of these two phages for the biocontrol of <i>E. hormaechei</i> contamination in food production systems.