Effective biocontrol of Enterococcus hirae in food products by a novel bacteriophage: Insights from genomic and phenotypic analyses.

Abstract

Enterococcus hirae is an opportunistic pathogen capable of causing severe bacteremia and intestinal infections, thereby posing a threat to food safety. The rise of multidrug resistance driven by antibiotic misuse, coupled with pervasive drug residues in food and the environment, necessitates the development of alternative therapeutic agents. Bacteriophages, which lyse host bacteria with high specificity without causing pollution, represent a promising class of eco-friendly bio-bactericides. In this study, 158 environmental samples were collected from wastewater treatment plants in Xinjiang, leading to the isolation of 13 E. hirae phages. Through systematic comparison, a novel phage vB_EhiS_LPP isolated from a wastewater treatment plant in Shihezi City, was selected for further investigation. This phage displays large plaques, a high titer, a short latent period, a large burst size, and excellent environmental stability. Functional assays further demonstrated that vB_EhiS_LPP exerts strong lytic activity against E. hirae isolates even at a low multiplicity of infection (MOI = 0.01). Whole genome analysis revealed that vB_EhiS_LPP shares less than 10% average nucleotide identity with known Enterococcal phages, suggesting that it may represent a new genus. Further safety assessment confirmed the absence of antibiotic resistance genes and virulence factors in the vB_EhiS_LPP genome. Moreover, this bacteriophage does not cause hemolysis in chicken red blood cells, supporting its compliance with food safety standards. Application evaluation in a food model showed that vB_EhiS_LPP effectively eliminated E. hirae within 6 to 10 h and significantly delayed food spoilage, highlighting its potential as a green bio-preservative agent in the food industry.