Molecular and physiological properties of bacteriophages from North America and Germany affecting the fire blight pathogen Erwinia amylovora

Abstract

SummaryFor possible control of fire blight affecting apple and pear trees, we characterized Erwinia amylovora phages from North America and Germany. The genome size determined by electron microscopy (EM) was confirmed by sequence data and major coat proteins were identified from gel bands by mass spectroscopy. By their morphology from EM data, φEa1h and φEa100 were assigned to the Podoviridae and φEa104 and φEa116 to the Myoviridae. Host ranges were essentially confined to E. amylovora, strains of the species Erwinia pyrifoliae, E. billingiae and even Pantoea stewartii were partially sensitive. The phages φEa1h and φEa100 were dependent on the amylovoran capsule of E. amylovora, φEa104 and φEa116 were not. The Myoviridae efficiently lysed their hosts and protected apple flowers significantly better than the Podoviridae against E. amylovora and should be preferred in biocontrol experiments. We have also isolated and partially characterized E. amylovora phages from apple orchards in Germany. They belong to the Podoviridae or Myoviridae with a host range similar to the phages isolated in North America. In EM measurements, the genome sizes of the Podoviridae were smaller than the genomes of the Myoviridae from North America and from Germany, which differed from each other in corresponding nucleotide sequences.

The tail‐associated depolymerase of Erwinia amylovora phage L1 mediates host cell adsorption and enzymatic capsule removal, which can enhance infection by other phage

“…The streptomycin‐resistant EPS‐negative mutant of Er. amylovora CFBP1430 carries a Tn5 insertion in amsD (Müller et al ., ,). Escherichia coli strain XL1‐Blue MRF' (Agilent Technologies, Santa Clara, CA, USA) was cultivated in LB at 37°C.…”

“…Bacteriophages specific for Er. amylovora were first reported several decades ago (Erskine, 1973), and more recently followed by studies regarding their characterization and application to control the pathogen (Schnabel and Jones, 2001;Gill et al, 2003;Born et al, 2011;Boulé et al, 2011;Müller et al, 2011b;Schwarczinger et al, 2011;Nagy et al, 2012). Clearly, the extreme specificity of phages to kill only their host bacteria without affecting other members of the bacterial ecosystem offers significant potential for environmentally friendly pathogen control.…”

Protection ofErwinia amylovorabacteriophage Y2 from UV-induced damage by natural compounds

“…2 Biocontrol of bacterial plant pathogens using bacteriophages (phages) has gained increased attention in agriculture as an alternative treatment, 3,4 and several studies have demonstrated the potential of phages to control fire blight. Phage-treatment significantly reduced the number of viable E. amylovora and symptom development in vitro, 5,6 on immature pear fruit, 7,8 on detached flowers, 8,9 and on apple trees. 9,10 Furthermore, "Erwiphage", a bacteriophage cocktail consisting of two phages, was recently introduced and is commercially available.…”

Absence of lysogeny in wild populations of Erwinia amylovora and Pantoea agglomerans

“…Bacteriophages (phages) offer a novel biological control mechanism since they are ubiquitous in the orchard environment, self‐replicating, nontoxic to eukaryotes, biodegradable unlike many agrochemicals and usually species and strain specific with no effect on indigenous bacteria. Phage‐mediated control of fire blight has been studied in laboratory and under field conditions (Erskine, ; Gill et al ., ; Lehman, ; Müller et al ., ; Svircev et al ., 2010; 2011; Boulé et al ., ; Schwarczinger et al ., ; Nagy et al ., ). Erskine () first demonstrated that a temperate phage that lysogenized a yellow saprophytic bacterium reduced fire blight symptoms when co‐inoculated with E. amylovora on pear slices.…”