CHARACTERISTICS OF ATYPICAL, CYTOCHROME OXIDASE-NEGATIVE AEROMONAS-SALMONICIDA ISOLATED FROM ULCERATED FLOUNDERS (PLATICHTHYS-FLESUS (L))

'Atypical', cytochrome oxidase-negative variants of the fish pathogen Aeromonas salmonicida, isolated from ulcerated flounder (Platichthys f lesus), were studied using different methods. Two of the strains posse ssed a protein that corresponded to the A-layer protein of Aer. salmon icida. The strains reacted with antibodies against the A-layer and mon oclonal antibodies against the O-antigen of typical Aer. salmonicida. These tests confirm that the isolates from flounder should be classifi ed as Aer. salmonicida. Analysis of the fatty acids showed that the is olates were rather homogenous but the values of the guanine plus cytos ine content of the DNA of the bacteria varied too much for any conclus ion to be drawn on their taxonomic location. The strains examined exhi bited several biochemical characters that differed from those of the t ype strains of Aer. salmonicida subsp. salmonicida and Aer. salmonicid a subsp. achromogenes. The results suggest that these 'atypical', cyto chrome oxidase-negative variants may form a new subspecies of Aer. sal monicida.