- Volume 68, Issue 8, 2018

In 1911, Sir Arnold Theiler isolated and described a parasite that was very similar to Anaplasma marginale but which was more centrally located within the erythrocytes of the host cells, and was much less pathogenic than A. marginale . He named the parasite A. marginale variety centrale. The name Anaplasma centrale , referring to the same organism, was published in Validation List No. 15 in 1984, but the publication was based on an erroneous assumption that Theiler had indicated that it was a separate species. Many authors have subsequently accepted this organism as a separate species, but evidence to indicate that it is a distinct species has never been presented. The near full-length 16S rRNA gene sequence, and the deduced amino acid sequences for groEL and msp4 from several isolates of A. marginale and A. centrale from around South Africa were compared with those of the A. marginale type strain, St Maries, and the A. centrale Israel strain and other reference sequences. Phylogenetic analyses of these sequences demonstrated that A. centrale consistently forms a separate clade from A. marginale , supported by high bootstrap values (≥90 %), revealing that there is divergence between these two organisms. In addition, we discuss distinctive characteristics which have been published recently, such as differences in Msp1a/Msp1aS gene structure, as well as genome architecture that provide further evidence to suggest that A. centrale is, in fact, a separate species. Our results, therefore, provide evidence to support the existing nomenclature, and confirm that A. centrale (ex Theiler 1911) Ristic and Kreier 1984 is, indeed, a distinct species.

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 %.

No common, unique genetic markers applicable to classification and phylogenetics for significant genera within the Propionibacteriaceae family have been suggested yet. Therefore, the aim of the study was to propose those genes in the genera Acidipropionibacterium , Cutibacterium , Propionibacterium and Pseudopropionibacterium . These genera were recently elicited from the genus Propionibacterium through whole genomic analyses. Three housekeeping genes, glyS, infB and rplB, were selected from many others according to the requirements for appropriate classification/phylogenetic markers. Concrete fragments of the genes were amplified using specific primers in most of the type (14) and 11 wild strains (originating from dairy products, human skin and the crop of a laying hen) recently classified into the genus Propionibacterium . Sequences obtained from amplicons were used to perform gene statistics and phylogenetic analyses with respect to applicability in classification, typing and phylogeny. The 16S rRNA gene sequences, still considered relevant in spite of its proven shortcomings as a basic tool for evaluation of bacterial phylogeny, were used as a baseline for comparative analyses. The statistics of the gene sequences revealed that the variable regions of all three genes have higher resolution capabilities among strains examined compared to the 16S rRNA gene analysis. Phylogenetic analyses based on individual gene sequences and their concatenate enabled to distinguish clusters of species belonging to the genera Acidipropionibacterium , Cutibacterium and Propionibacterium , which corresponds with a recently reported genomic study. Thus, the crucial importance of this study is the economically advantageous classification and typing of propionibacterial isolates and strains through the three gene regions in contrast to the requirement for whole genomic assays.