# Genomic and in vitro characterization of two lytic bacteriophages infecting multidrug-resistant Erwinia sp. strain AnSW2-5

## TL;DR

Two new bacteriophages were studied for their ability to kill drug-resistant Erwinia bacteria, showing strong effectiveness and resistance suppression.

## Contribution

Discovery and characterization of two lytic bacteriophages with synergistic effects against MDR Erwinia sp.

## Key findings

- Phage cocktail reduced bacteria by >80% and suppressed growth for 72 hours.
- Dual-phage treatment prevented resistant mutant emergence with FoR < 10⁻⁸.
- P-A and P-K phages showed distinct lytic properties, including latent period and burst size differences.

## Abstract

Multidrug-resistant (MDR) Erwinia pathogens present a critical threat to global crop health and agricultural sustainability. In this study, we characterized two novel lytic bacteriophages, AnSW2-5-P-A (family Autographiviridae) and AnSW2-5-P-K (class Caudoviricetes), targeting the MDR Erwinia sp. strain AnSW2-5. Comparative genomics and TEM analysis revealed distinct virion architectures and confirmed the absence of lysogeny-associated genes, ensuring their safety as biocontrol agents. One-step growth assays demonstrated that P-A has a shorter latent period (~ 20 min), while P-K exhibits a significantly larger burst size (~ 110 PFU/cell). In co-culture assays, the dual-phage cocktail demonstrated a profound synergistic effect, achieving > 80% bacterial reduction (p < 0.05) and maintaining sustained suppression of the host for 72 h. Notably, the cocktail effectively prevented the emergence of resistant mutants, reducing the frequency of resistance (FoR) to below the limit of detection (< 10⁻⁸). These findings highlight the potential of using genetically diverse phage pairs with complementary lytic activities as a robust, resistance-suppressive biocontrol strategy against MDR phytopathogens.

The online version contains supplementary material available at 10.1038/s41598-026-39563-8.