Molecular diversity of Renibacterium salmoninarum isolates determined by randomly amplified polymorphic DNA analysis

The molecular diversity among 60 isolates of Renibacterium salmoninarum whi ch differ in place and date of isolation was investigated by using randomly amplified polymorphic DNA (RAPD) analysis. Isolates were grouped into 21 b anding patterns which did not reflect the biological source. Four 16S-23S r RNA intergenic spacer (ITS1) sequence variations and two alleles of an exac t tandem repeat locus, ETR-A were the bases for formation of distinct group s within the RAPD clusters. This study provides evidence that the most comm on ITS1 sequence variant, SV1, possesses two copies of a 51-bp repeat unit at ETR-A and has been widely dispersed among countries which are associated with mainstream intensive salmonid culture.