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A collection of 94 Vibrio isolates closely related to Vibrio harveyi, together with named reference and type strains, were investigated for phenotypic and genotypic properties. Using amplified fragment length polymorphism (AFLP), nine clusters were recognized. The largest cluster (n = 36), considered to be the bona fide V. harveyi group, contained the type strains of V. harveyi and Vibrio carchariae and most of the strains isolated from fish. The type strains of all other species, including Vibrio alginolflicus, Vibrio parahaemo/flicus, Vibrio campbellii and Vibrio natriegens, clustered outside this group. By ribotyping, V. harveyi and V. carchariae patterns were very similar, insofar as they shared most bands. The V. campbellii type strain had several bands in common with the type strains of both V. harveyi and V. carchariae, whereas the other species were clearly distinct from these three species. DNA-DNA hybridization experiments showed 88% DNA binding between the type strains of V. harveyi and V. carchariae, whereas the DNA binding between V. harveyi and V. campbellii was 40%. Although the delineation of the species V. harveyi is still uncertain, the authors propose, on the basis of a number of tests, to delineate a core of V. harveyi strains which contained the type strains of both V. harveyi and V. carchariae. It is concluded that V. camhariae is the junior synonym of V. harveyi.

The present paper summarizes the serotyping scheme of the fish pathogenic bacterium Vibrio anguillarum and defines seven additional O-serogroups. Strains, collected in our laboratories that were nontypable with antisera against the previously defined 16 O-serotypes, were used for generating new antisera and were characterized further by means of LPS profiles, Western blots, and serological reactions. On the basis of the results, it is suggested that the seven new O-serogroups are to be included in the existing serotyping system as serotypes O17-O23. However, the existence of further V. anguillarum strains that were not typable with any of the 23 O-antisera suggested the existence of additional O-serotypes within this species. The relevance of the description of additional O-serotypes for the species V. anguillarum is discussed.

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One hundred and twenty-nine strains of Vibrio anguillarum serovar O2 and 14 strains of Vibrio ordalii were ribotyped and examined for plasmid contents. A total of 35 different ribotypes were detected. The V. anguillarum serovar O2 strains were divided into 32 different ribotypes. The V. ordalii strains showed three different ribotypes, clearly distinct from those of the V. anguillarum strains. Ribotypes were separated into seven clusters, of which one comprised the V. ordalii strains. Clustering of the strains indicated a genetic difference between North European and South European V. anguillarum O2 strains. Sero-subgroups O2a and O2b shared ribotypes; however, three of the clusters did not include O2a strains. All V. ordalii strains had a plasmid of 32 kb. This plasmid was not detected in any of the V. anguillarum strains. Seventeen different plasmid profiles with 17 different sized plasmids were detected among the V. anguillarum strains. Most of the plasmids were small (< 6 kb) and found in several strains. Except for one South European strain, plasmids were detected only in the North European strains of V. anguillarum O2.