Classification of genera of Pasteurellaceae using conserved predicted protein sequences.

The aim of the investigation was to investigate the phylogeny of the 49 type strains of species of Pasteurellaceae and three genomospecies, which are available with whole genomic sequences. The genomes were downloaded from National Center for Biotechnological Information and for three species of Avibacterium sequenced in the present investigation. From the predicted protein sequences of proteins, which were conserved in all genomes, 31 proteins were randomly selected for the study. The protein sequences were concatenated for each taxon, and a multiple alignment reconstructed for the 52 taxa. Phylogenetic analysis was performed by using the maximum-likelihood and neighbour-joining methods and confirmed the classification of the genera, which have been classified based on phylogenetic analysis of 16S rRNA gene sequences. The comparison linked [Haemophilus]parainfluezae and [Haemophilus] pittmania with Haemophilus influenzae (type species of genus) although at a much lower level than observed for Haemophilus aegyptius, H. influenzae and Haemophilus haemolyticus. The comparison documented that three, three and nine species of Actinobacillus, Pasteurella and Haemophilus, respectively, are not properly classified at genus level. Similar conclusions have been drawn by 16S rRNA gene sequence comparisons. The highest inter genus pairwise similarity was 88 % based on the comparison of the 31 concatenated protein sequences of the species included in the comparison. The level of intra genus pairwise similarity was also 88 %.