Immunoelectron microscopic demonstration that Renibacterium salmoninarum is encapsulated.

The cell surfaces of four strains of Renibacterium salmoninarum, including the type strain Lea-7-74T, were examined by transmission electron microscopy after immuno-stabilization and staining with ruthenium red. Cells were covered with a layer of capsular material whose thickness varied between 30 to 60 nm. Our results indicate that R. salmoninarum is encapsulated.