Properties of Erwinia amylovora phages from North America and Germany and their possible use to control fire blight
The E. amylovora phages ΦEa1h, ΦEa100, ΦEa104, and ΦEa116, isolated in the USA, were visualized in the electron microscope, and the size of their genomes was 45 or 85 kb. Phages ΦEa1h and ΦEa100 are Podoviridae, ΦEa104 and ΦEa116 Myoviridae. The phages were also characterized for their host range, stability and growth on E. amylovora. They weakly interacted with E. billingiae and not with E. tasmaniensis. For attachment and infection, the phages ΦEa1h and ΦEa100 are dependent on the amylovoran capsule of E. amylovora. High EPS-producers such as E. pyrifoliae strains from Korea are less sensitive, probably due to lack of additional receptors. The bacteriophages ΦEa104 and ΦEa116 are not EPS dependent and efficiently lyse ams mutants, deficient in EPS-production. Phages ΦEa104 and ΦEa116 as well as the Podoviridae protect flowers and immature pears in reducing fire blight symptoms. From experimental orchards in Germany we have isolated E. amylovora phages, which also belong to the Podoviridae or Myoviridae. Their genome size was only 40 kb with additional differences to the American phages for their genomic sequences.