Isolation and phenotypic and morphological characterization of the first Podoviridae lytic bacteriophages φA38 and φA41 infecting Pectobacterium parmentieri (former Pectobacterium wasabiae).
Two bacteriophages, φA38 and φA41, infecting Pectobacterium parmentieri strain SCC 3193 (former Pectobacterium wasabiae strain SCC 3193) were isolated from arable soil samples collected in different regions of Poland. φA38 and φA41 have a typical morphology of the members of the family Podoviride and order Caudovirales, with a head diameter of ca. 60 nm and tail length of ca. 20 nm. Phages φA38 and φA41 exhibited a similar RFLP pattern with Csp6I restriction endonuclease. They were stable in a range of pHs, temperatures and osmolarities but were rapidly inactivated by UV light. During the first 20 min., 74 and 69% of φA38 and φA41 phages, respectively, were adsorbed to SCC 3193 cells. In one-step growth experiments, φA38 and φA41 showed latent period of ca. 20-30 min and burst size of 102 and 141 phages, respectively. The optimal multiplicity of infection (MOI) was calculated to be 0.01 for both bacteriophages. In the host range experiments, both phages were able to infect six from 21 of the tested P. parmentieri isolates but the phages were unable to infect other members of the Pectobacterium spp. or Dickeya spp. In the proof-of-concept experiments, φA38 and φA41 were able to inhibit the growth of P. parmentieri strain SCC 3193 and to protect potato tuber tissue maceration caused by the bacterium. The potential use of φA38 and φA41 bacteriophages for the biocontrol of P. parmentieri in potato is discussed.