The first single-stranded DNA virus targeting Pectobacterium belongs to the family Microviridae and demonstrates a broad host range to Pectobacterium brasiliense soft rot pathogens

Pectobacterium brasiliense (Pbr) is known to be one of the most virulent Pectobacterium species and is generally widely distributed across the globe, especially known for causing soft rot in potato-tubers and black leg in potato-plants. Currently no treatment mechanism exists, and many studies have focused on alternative treatment approaches such as biocontrol agents. Several studies have used phages targeting Pectobacterium species as effective biocontrol agents. This study is the first description of a single-stranded DNA phage belonging to the family Microviridae that targets Pectobacterium. The novel Pectobacterium phage Mimer is proposed to belong to a new genus within the subfamily Bullavirinae in the family Microviridae. Phage Mimer has a genome size of 5879 nt with twelve predicted gene products. Seven out of twelve gene products could be assigned with a function based on either amino acid sequence or structural similarity. Gene synteny and phylogenetic analyses suggest that phage Mimer is part of the subfamily Bullavirinae. Phage Mimer proved to infect a broad range of Pbr isolates but showed a poor adsorption rate as only 17% of phage particles adsorbed within 10 min on the isolation host. Growth kinetics showed phage Mimer to have a latent period of 65 min and an average burst size of approximately 79 virions per cell. Phage Mimer is the first ssDNA phage targeting Pectobacterium and could be a promising biocontrol agent with great therapeutic potential, based on both the small genome size and the well-known genome architecture of model phage phiX174.