Farm-adapted multicomponent bacteriophage preparation for environmental biocontrol in commercial dairy cattle housing: A One Health approach.

Abstract

Background and aim: The increasing occurrence of antimicrobial-resistant bacteria in livestock environments highlights the need for sustainable alternatives to conventional antimicrobials. Bacteriophages offer a targeted approach for reducing bacterial contamination while supporting antimicrobial stewardship. This study aimed to develop and evaluate a farm-adapted multicomponent bacteriophage preparation for environmental biocontrol in commercial dairy cattle housing.

Materials and methods: Bacterial strains and bacteriophages were isolated from samples collected at a commercial dairy farm. Selected bacteriophages were characterized for host range, efficiency of plating, multiplicity of infection, and host range expansion through phage adaptation. Purified phage clones were subjected to whole-genome sequencing and bioinformatic analysis. A multicomponent bacteriophage preparation was formulated and lyophilized to facilitate storage and field application. The preparation was subsequently applied to selected environmental surfaces in dairy cattle housing, and bacterial recovery before and after treatment was evaluated using microbiological methods.

Results: Phage screening and adaptation enabled the selection of bacteriophages with complementary activity against bacterial isolates recovered from the dairy farm environment. Adaptation expanded the lytic activity of selected phages against previously less susceptible bacterial hosts. Genomic characterization supported the selection of phages for inclusion in the final preparation, while formulation and lyophilization yielded a preparation suitable for field application. Following environmental application under commercial dairy farm conditions, qualitative changes in bacterial recovery were observed on treated surfaces, demonstrating the feasibility of using a farm-adapted bacteriophage preparation for environmental biocontrol. The findings also demonstrated the practical integration of bacterial surveillance, phage isolation, adaptation, genomic characterization, formulation, and on-farm application within a single biocontrol strategy.

Conclusion: A farm-adapted multicomponent bacteriophage preparation can provide a practical, targeted approach for environmental bacterial control in commercial dairy cattle housing. The combination of locally isolated phages, host range adaptation, genomic characterization, and a field-applicable lyophilized formulation is a key strength of this approach. These findings provide a foundation for further controlled studies using quantitative microbial assessments to determine efficacy, optimize application protocols, and evaluate the contribution of bacteriophage-based environmental interventions to antimicrobial stewardship and One Health strategies in livestock production.