Spontaneous Resistance of Erwinia amylovora Against Bacteriophage Y2 Affects Infectivity of Multiple Phages

Characterizations of Newly Isolated Erwinia amylovora Loessnervirus-like Bacteriophages from Hungary

This study explores alternative methods to combat bacterial infections like fire blight caused by Erwinia amylovora (Ea) using bacteriophages as potential antimicrobial agents. Two lytic phages, Ea PF 7 and Ea PF 9, were isolated from apple samples and classified as Loessnervirus-like based on their genomes. Both phages showed strong efficacy, lysing 95% of the tested 37 Ea strains. They inhibited bacterial growth for up to 10 h, even at low infection rates. The phages had a short latent period of 10 min and produced high burst sizes of 108 and 125 phage particles per infected cell. Stability tests revealed that both phages were stable at moderate temperatures (37-45 °C) and within a pH range of 4-10. However, their viability decreased at higher temperatures and extreme pH levels. Both phages exhibited notable desiccation tolerance and moderate resistance to UV-B radiation during UV testing. The phages were exposed to carefully controlled irradiation, considering factors like lamp type, radiation intensity, exposure time, and object distance. This method introduces a complex approach to research, ensuring repeatable and comparable results. These findings suggest that Ea PF 7 and Ea PF 9 hold promise as antimicrobial agents for therapeutic and biotechnological applications, potentially helping to combat antibiotic resistance in the future.

Advancements in Bacteriophages for the Fire Blight Pathogen Erwinia amylovora

Erwinia amylovora, the causative agent of fire blight, causes significant economic losses for farmers worldwide by inflicting severe damage to the production and quality of plants in the Rosaceae family. Historically, fire blight control has primarily relied on the application of copper compounds and antibiotics, such as streptomycin. However, the emergence of antibiotic-resistant strains and growing environmental concerns have highlighted the need for alternative control methods. Recently, there has been a growing interest in adopting bacteriophages (phages) as a biological control strategy. Phages have demonstrated efficacy against the bacterial plant pathogen E. amylovora, including strains that have developed antibiotic resistance. The advantages of phage therapy includes its minimal impact on microbial community equilibrium, the lack of a detrimental impact on plants and beneficial microorganisms, and its capacity to eradicate drug-resistant bacteria. This review addresses recent advances in the isolation and characterization of E. amylovora phages, including their morphology, host range, lysis exertion, genomic characterization, and lysis mechanisms. Furthermore, this review evaluates the environmental tolerance of E. amylovora phages. Despite their potential, E. amylovora phages face certain challenges in practical applications, including stability issues and the risk of lysogenic conversion. This comprehensive review examines the latest developments in the application of phages for controlling fire blight and highlights the potential of E. amylovora phages in plant protection strategies.

The metastable associations of bacteriophages and Erwinia amylovora

Bacteriophages are often considered as possible agents of biological control of unwanted bacterial populations in medicine, agriculture and food industry. Although the virulent phages can efficiently kill the infected host cells but at the population level phage attack not always leads to the host population collapse but may result in establishment of a more or less stable co-existence. The mechanism of the long-term stabilization of the mixed phage-host cultures is poorly understood. Here we describe bacteriophages VyarbaL and Hena2, the members of the Molineuxvirinae and the Ounavirinae subfamilies, respectively, that are able to form the pseudolysogenic associations (PA) with their host Erwinia amylovora 1/79Sm on solid media. These PAs were stable through multiple passages. The phenomenon of the PA formation between a bacterial culture and bacteriophages decreases the effectiveness of bacteriophage-mediated biological control agents based on lytic bacteriophages.