Isolation and identification of a bacteriophage capable of infecting Streptococcus suis type 2 strains

Streptococcus suis (S. suis) type 2 infection is considered to be a major problem worldwide in the swine industry. Studying phages of S. suis type 2 would be crucial for understanding the ecology and evolution of the Gram-positive bacteria. However, at the present, very little is known about them. An S. suis type 2 bacteriophage, named SMP, was isolated from nasal swabs of healthy Bama minipigs and was characterized at the microbiological and molecular levels. Phage SMP had an isometric head of 50 nm, a noncontractile tail of approximately 135 nm, and a linear double-stranded DNA genome. The host range of phage SMP was limited to 2 of 24 S. suis type 2 strains tested. The genome of phage SMP contained 36,216 bp with an average G + C content of 41.6%.