# Characteristics, Whole Genome Analysis of a Virulent Phage from Avian-Derived Enterococcus faecalis and Its Application in Poultry Product Processing Safety

## TL;DR

A new virulent phage was isolated from poultry sewage and shown to effectively control E. faecalis contamination in poultry products.

## Contribution

The study identifies and characterizes a novel phage with strong lytic activity and biosafety for poultry product safety.

## Key findings

- The phage vB-Efa1 belongs to the Siphoviridae family and has a genome of 166,586 bp with no antibiotic resistance genes.
- Phage titer is significantly higher at 25 °C than at 4 °C, indicating temperature's key role in its proliferation.
- The phage shows good stability at 25–37 °C, pH 6–8, and 4 °C, with a latent period of 30 min and a titer of 8.87 lg PFU/mL.

## Abstract

To explore high-quality phage resources for controlling Enterococcus faecalis (E. faecalis) contamination, a virulent phage vB-Efa1 was isolated and purified from poultry slaughterhouse sewage in this study. Its biological characteristics, whole-genome features, and potential in ensuring poultry product processing safety were systematically investigated. The phage belongs to the Siphoviridae family, with an optimal multiplicity of infection (MOI) of 0.1 and a titer of 8.87 lg PFU/mL; it has a 30 min latent period and stable lytic activity, retaining good stability at 25–37 °C, pH 6–8, and 4 °C. Its circular whole genome is 166,586 bp in length with a GC content of 35.46%, encoding 276 genes; no antibiotic resistance genes were detected, and only one low-pathogenic-risk virulence-related sequence was identified. Application tests in poultry products revealed that temperature is the key factor regulating phage titer: the titer stably maintained 5.5–6.6 lg PFU/mL at 4 °C, while proliferating significantly at 25 °C, reaching 7.55–8.38 lg PFU/mL at 12 h. Collectively, vB-Efa1 exhibits superior biological traits, environmental adaptability, and biosafety, making it a promising biocontrol candidate for mitigating E. faecalis contamination in poultry products.