Evaluation of the Antimicrobial Potential and Characterization of Novel T7-Like Erwinia Bacteriophages

SIMPLE SUMMARY: Erwinia amylovora and E. pyrifoliae cause Erwinia blight, which damage pome fruits, and are highly contagious. We propose the use of bacteriophages to control these two pathogens simultaneously. Many drugs have been used in South Korea for the quick control of blight disease caused by both these species. This can result in antibiotic resistance; hence, phage cocktails have been suggested as an alternative. In this study, we observed that phage cocktails, including four isolated phages, exhibited extensive strain spectra and potential for rapid bacterial control. This study demonstrated the potential of a phage cocktail to replace antibiotics as biocontrol agents against Erwinia blight. ABSTRACT: The recent outbreak of blight in pome fruit plants has been a major concern as there are two indistinguishable Erwinia species, Erwinia amylovora and E. pyrifoliae, which cause blight in South Korea. Although there is a strict management protocol consisting of antibiotic-based prevention, the area and the number of cases of outbreaks have increased. In this study, we isolated four bacteriophages, pEp_SNUABM_03, 04, 11, and 12, that infect both E. amylovora and E. pyrifoliae and evaluated their potential as antimicrobial agents for administration against Erwinia-originated blight in South Korea. Morphological analysis revealed that all phages had podovirus-like capsids. The phage cocktail showed a broad spectrum of infectivity, infecting 98.91% of E. amylovora and 100% of E. pyrifoliae strains. The antibacterial effect was observed after long-term cocktail treatment against E. amylovora, whereas it was observed for both short- and long-term treatments against E. pyrifoliae. Genomic analysis verified that the phages did not encode harmful genes such as antibiotic resistance or virulence genes. All phages were stable under general orchard conditions. Collectively, we provided basic data on the potential of phages as biocontrol agents that target both E. amylovora and E. pyrifoliae.