Phenotypic and genotypic characterization of Vibrio viscosus sp. nov. and Vibrio wodanis sp. nov. isolated from Atlantic salmon (Salmo salar) with 'winter ulcer'.

Two groups of Vibrio strains isolated from Atlantic salmon with 'winter ulcer' were characterized phenotypically and genotypically. The data obtained indicated that each of the two groups represented a new species in the genus Vibrio. The names Vibrio viscosus sp. nov. [type strain NVI 88/478T (= NCIMB 13584T)] and Vibrio wodanis sp. nov. [type strain NVI 88/441T (= NCIMB 13582T)] are proposed for the new species. V. viscosus strains exhibited a similar total DNA RFLP pattern and a similar plasmid DNA profile. DNA relatedness (hydroxyapatite method) of the V. viscosus type strain to nine other V. viscosus strains was 81-93% at 60 degrees C. Divergence within related sequences was 0.0-1.5% and relatedness at 75 degrees C was 74-100%. V. wodanis strains exhibited marked heterogeneity on the basis of RFLP analysis and plasmid profiles. DNA relatedness of the V. wodanis type strain to 10 other V. wodanis strains was 66-94% at 60 degrees C. Divergence within related sequences was 0.0-1.5% and relatedness at 75 degrees C was 55-97%. Relatedness between V. viscosus and V. wodanis type strains was approximately 20%. Among other Vibrio species, the closest relative of V. viscosus was Vibrio marinus (ATCC 15381T) (43% relatedness at 60 degrees C) and that of V. wodanis was Vibrio logei (ATCC 15382) (57% relatedness at 60 degrees C). These same pairs were the closest phenotypic relatives. DNA sequence analysis of the 16S rRNA gene of V. viscosus indicated an intimate relationship to V. marinus. A total evaluation of the results, however, supports V. viscosus to be a separate species in the genus Vibrio. The analysis of the sequence of the 16S rRNA gene of V. wodanis supports that V. logei (ATCC 15382) was the most related species. Ability to degrade casein, oxidative production of acid from trehalose and production of lysine decarboxylase are important biochemical tests that will differentiate between V. viscosus, V. wodanis, V. marinus (ATCC 15381T) and V. logei (ATCC 15382).