Classification of Bisgaard's taxa 14 and 32 and a taxon from kestrels demonstrating satellitic growth and proposal of Spirabiliibacterium gen. nov., including the description of three species: Spirabiliibacterium mucosae sp. nov., Spirabiliibacterium pneumoniae sp. nov. and Spirabiliibacterium falconis sp. nov

Classification of Bisgaard taxon 6 and taxon 10 as Exercitatus varius gen. nov., sp. nov

Forty-one isolates of Bisgaard taxon 6 obtained from guinea pigs, pandas, pigs and muskrat and isolates of taxon 10 from horses and horse bites in humans were subjected phenotypic characterization. Production of acid from (-)-d-mannitol, (-)-d-sorbitol and (+)-d-glycogen separated taxon 10 (positive) from taxon 6 (negative), while from two to 11 phenotypic characteristics separated taxa 6 and 10 from the 32 genera of Pasteurellaceae reported so far. Forty-four strains were genetically characterized. Sequencing of 16S rRNA genes documented a monophyletic relationship at the species level and the highest 16S rRNA gene sequence similarity of 95.6 % to other species was found between strain CCUG 15568T and the type strain of Mannheimia glucosida (CCUG 38457T). Digital DNA-DNA hybridization (dDDH) values predicted from whole genomic sequences between CCUG 15568T and other characterized strains of taxa 6 and 10 were 69.3-99.9 %. The average nucleotide identity values were higher than 95 % for all strains. The highest dDDH value of 29 % outside the taxa 6 and 10 group was obtained with the genome of the type strain of [Actinobacillus] succinogenes, indicating a separate taxonomic status at species level to taxa 6 and 10. The phylogenetic comparison of concatenated conserved protein sequences showed the unique position of the taxa investigated in the current study which qualified for the status of a new genus since the highest identity was found with Basfia with 79 %, well below the upper threshold between genera of 85 %. Based upon the low genetic similarity to other genera of the family Pasteurellaceae and a unique phenotype, we suggest that Bisgaard taxa 6 and 10 should be classified as Exercitatus varius gen. nov., sp. nov. The G+C of the type strain of Exercitatus varius, 8.5T (=CCUG 15568T=DSM 115565T), is 46.2 mol%, calculated from the whole genome.

Foremost report of the whole genome of Spirabiliibacterium mucosae from India and comparative genomics of the novel genus Spirabiliibacterium

Several Pasteurella like organisms isolated from various avian species were recently reclassified into new genus based on whole genome sequence analysis. One such Pasteurella like organism, Bisgaard taxon 14 was classified as Spirabiliibacterium mucosae. In the present study, a Gram-negative organism was isolated from ailing pigeons with respiratory infection from a farm in Tamil Nadu, India and the organism was misidentified as Burkholderia mallei by Vitek 2 compact system based on biochemical characterization. Since, B. mallei is highly pathogenic and zoonotic, to further confirm, 16S rDNA sequencing and analysis was carried out which revealed that the strain belonged to Bisgaard taxon 14 (Spirabiliibacterium mucosae). To further confirm the findings, whole genome sequencing of the isolate was performed. Whole genome phylogeny and average nucleotide identity (ANI) analysis showed that the genome was closely matching with Spirabiliibacterium mucosae type strain 20,609 /3. Hence, the strain from pigeon was named as Spirabiliibacterium mucosae TN_CUL_2021 and the genome was submitted in NCBI SRA database. The genome of S. mucosase TN_CUL_2021 is only the second genome available worldwide in the NCBI database. Comparative genome analysis of 26 Pasteurellaceae family strains revealed 1101 genes specific for Spirabiliibacterium mucosae. Similarly, luxS virulence gene was found only in S. mucosae and Bisgaardia hudsonensis strains. Since there are only 2 genomes available in the NCBI genome database, further studies on isolation of S. mucosae needs to be carried out to identify its epidemiology and pathogenesis so as to develop better diagnostic assays and vaccines.

An Update on Novel Taxa and Revised Taxonomic Status of Bacteria Isolated from Domestic Animals Described in 2018 to 2021

Novel bacterial taxonomy and nomenclature revisions can have significant impacts on clinical practice, disease epidemiology, and veterinary microbiology laboratory operations. Expansion of research on the microbiota of humans, animals, and insects has significant potential impacts on the taxonomy of organisms of clinical interest. Implications of taxonomic changes may be especially important when considering zoonotic diseases. Here, we address novel taxonomy and nomenclature revisions of veterinary significance. Noteworthy discussion centers around descriptions of novel mastitis pathogens in Streptococcaceae, Staphylococcaceae, and Actinomycetaceae; bovine reproductive tract pathogens in Corynebacteriaceae; novel members of Mannheimia spp., Leptospira spp., and Mycobacterium spp.; the transfer of Ochrobactrum spp. to Brucella spp.; and revisions to the genus Mycoplasma.

Update on Novel Taxa and Revised Taxonomic Status of Bacteria Isolated from Nondomestic Animals Described in 2018 to 2021

Revisions and new additions to bacterial taxonomy can have a significant widespread impact on clinical practice, infectious disease epidemiology, veterinary microbiology laboratory operations, and wildlife conservation efforts. The expansion of genome sequencing technologies has revolutionized our knowledge of the microbiota of humans, animals, and insects. Here, we address novel taxonomy and nomenclature revisions of veterinary significance that impact bacteria isolated from nondomestic wildlife, with emphasis being placed on bacteria that are associated with disease in their hosts or were isolated from host animal species that are culturally significant, are a target of conservation efforts, or serve as reservoirs for human pathogens.

Comparative Genomics Analyses Support the Reclassification of Bisgaard Taxon 40 as Mergibacter gen. nov., With Mergibacter septicus sp. nov. as Type Species: Novel Insights Into the Phylogeny and Virulence Factors of a Pasteurellaceae Family Member Associated With Mortality Events in Seabirds

The Pasteurellaceae family has been associated with fatal diseases in numerous avian species. Several new taxa within this family, including Bisgaard taxon 40, have been recently described in wild birds, but their genomic characteristics and pathogenicity are not well understood. We isolated Bisgaard taxon 40 from four species of seabirds, including one sampled during a mass, multi-species mortality event in Florida, United States. Here, we present a comprehensive phenotypic and genetic characterization of Bisgaard taxon 40 and comparative genomic analysis with reference strains from the Pasteurellaceae family, aiming at determining its phylogenetic position, antimicrobial susceptibility profile, and identifying putative virulence factors. In silico multilocus sequence-based and whole-genome-based phylogenetic analysis clustered all Bisgaard taxon 40 strains together on a distinct branch separated from the other members of the Pasteurellaceae family, indicating that Bisgaard taxon 40 could represent a new genus. These findings were further supported by protein similarity analyses using the concatenation of 31 conserved proteins and other taxonomic approaches such as the percentage of conserved protein test. Additionally, several putative virulence factors were identified, including those associated with adhesion (capsule, ompA, ompH) and colonization (exbD, fur, galU, galE, lpxA, lpxC, and kdsA) of the host and a cytolethal distending toxin (cdt), which may have played a role in disease development leading to the mortality event. Considerably low minimum inhibitory concentrations (MICs) were found for all the drugs tested, in concordance with the absence of antimicrobial resistance genes in these genomes. The novel findings of this study highlight genomic and phenotypic characteristics of this bacterium, providing insights into genome evolution and pathogenicity. We propose a reclassification of these organisms within the Pasteurellaceae family, designated as Mergibacter gen. nov., with Mergibacter septicus sp. nov. as the type species. The type strain is Mergibacter septicus A25201^T (=DSM 112696).