Genetic variability among strains of Flavobacterium columnare (formerly Flexibacter columnaris) was characterized using restriction fragment length polymorphism (RFLP) analysis of 16S rDNA, 16S rDNA sequencing, and DNA-DNA hybridization. A total of 23 Fl. columnare strains isolated from diseased fishes in various areas were divided into three distinct genomic groups. The main group, genomovar 1 consisted of 20 strains, including the type strain. Two strains were assigned to genomovar 2, and one to genomovar 3. However, as we found their phenotypic characteristics to be identical, there is no evidence to classify strains of these genomovars as belonging to new species or sub-species.
The Japanese Society of Fish Pathology