Isolation of Bacteriophages Against Curtobacterium flaccumfaciens pv. flaccumfaciens and Their Biocontrol Effects

Curtobacterium flaccumfaciens pv. flaccumfaciens, the bacterial wilt pathogen causing significant losses in bean production, is a difficult pathogen to control due to its ability to be transmitted by seeds and its systemic course. This study aimed to isolate and enrich lytic bacteriophages effective against C. flaccumfaciens pv. flaccumfaciens and to determine their titers and host ranges. Phages obtained from wastewater and bean production field soil samples collected from Iğdır-Merkez were confirmed using the double-layer agar method. In the screening conducted with 16 C. flaccumfaciens pv. flaccumfaciens strains, Φ47-cu, Φ457-cu, Φ66-cu, Φ351-cu, Φ452-cu, Φ460-cu, Φ332-cu, and Φ20-cu were isolated. In host range tests, the susceptibilities on C. flaccumfaciens pv. flaccumfaciens were found to be variable; in particular, Φ66-cu, Φ332-cu, and Φ460-cu stood out with their broad/effective host profile and high lytic activity. In cross-host evaluations, distinct zones were observed in Erwinia amylovora strains, while limited biocontrol efficacy was noted in Xanthomonas axonopodis pv. vesicatoria and Acidovorax citrulli. Patterns in phage–host relationships were supported by heat mapping, hierarchical clustering, network analysis, and PCA. The findings indicate that some isolates exhibit a narrow host range, while others exhibit a broader host range; selected phages can be considered as biocontrol candidates against C. flaccumfaciens pv. flaccumfaciens.