Taxonomy of some recently described avianpasteurella/ actinobacillus‐likeorganisms as indicated by deoxyribonucleic acid relatedness

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Abstract
Members of the family Pasteurellaceae Pohl 1981 are frequently encountered in birds as parasites or pathogens, e.g. the well‐known species Pasteurella multocida, Pasteurella gallinarum, Haemophilus paragalli‐narum, and three species containing strains that had been previously classified as "Haemophilusavium"(Pasteurella avium, Pasteurella volan‐tium, and an unnamed Pasteurella species defined by Mutters et al., 1985). A variety of additional taxa which had been tentatively assigned to the family do not belong to recognised species and could not even be classified to the genus level. In the present investigation selected Pasteurella/Actinobacillus‐like isolates from fowl and zoo birds were examined for their genetic relationships with established species of Pasteurellaceae, using the renaturation method of deoxyribonucleic acid (DNA):DNA hybridisation. Guanine plus cytosine contents and genome masses were also considered. On the basis of DNA relatedness (1) the genus Pasteurella sensu stricto was extended to include Bisgaard's taxa 1 and 4 as two new Pasteurella species. (2) Bisgaard's taxa 2 and 3 and some phenotypically similar organisms isolated from zoo birds were shown to form a large distinct group which seems to represent a new genus with several species within the family Pasteurellaceae. (3) Another large heterogeneous, genus‐like group consisted of strains labelled "Actinobacillus salpingitid is” and the phenotypically similar “Avian Pasteurella haemolytica‐like” organisms; this group was placed in the close vicinity of the genus Actinobacillus. (4) Finally, a group of isolates labelled “Avian haemolytic Actinobacillus‐like” organisms appeared to be heterogeneous on the species level but could be included in the genus Actinobacillus on the basis of DNA binding data. By co‐evaluation of genetic relatedness and phenotypic features of avian Pasteurella/Actinobacillus‐like isolates some diagnostically useful criteria have been detected.