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.

Description of Pseudoclavibacter triregionum sp. nov. from human blood and Pseudoclavibacter albus comb. nov., and revised classification of the genus Pseudoclavibacter: proposal of Caespitibacter gen. nov., with Caespitibacter soli comb. nov. and Caespitibacter caeni comb. nov

We present polyphasic taxonomic data to demonstrate that strain 125703-2019^T, a human blood isolate, represents a novel species within the genus Pseudoclavibacter, and to reclassify the illegitimate Zimmermannella alba Lin et al., 2004 as Pseudoclavibacter albus comb. nov. Upon primary isolation, strain 125703-2019^T could not be identified reliably using MALDI-TOF mass spectrometry during routine diagnostic work, but partial 16S rRNA gene sequence analysis revealed that it belonged to the genus Pseudoclavibacter. Average nucleotide identity and digital DNA-DNA hybridisation analyses confirmed that it represented a novel species within this genus. A detailed physiological characterisation yielded differential tests between the novel species and its nearest neighbor taxa, which could also be differentiated using MALDI-TOF mass spectrometry. We propose to formally classify this strain into the novel species Pseudoclavibacter triregionum sp. nov., with strain 125703-2019^T (= R-76471^T, LMG 31777^T, CCUG 74796^T) as the type strain. The whole-genome assembly of strain 125703-2019^T has a size of 2.4 Mb and a G + C content of 72.74%. A Pseudoclavibacter pangenome analysis revealed that 667 gene clusters were exclusively present in strain 125703-2019^T. While these gene clusters were enriched in several COG functional categories, this analysis did not reveal functions that explained the occurrence of this species in human infection. Finally, several phylogenetic and phylogenomic analyses demonstrated that the genus Pseudoclavibacter is polyphyletic with Pseudoclavibacter soli and Pseudoclavibacter caeni representing a unique and deeply branching line of descent within the family Microbacteriaceae. We therefore also propose to reclassify both species into the novel genus Caespitibacter gen. nov. as Caespitibacter soli comb. nov. and Caespitibacter caeni comb. nov., respectively, and with C. soli comb. nov. as the type species.

Gulosibacter hominis sp. nov.: a novel human microbiome bacterium that may cause opportunistic infections

We present genomic, phylogenomic, and phenotypic taxonomic data to demonstrate that three human ear isolates represent a novel species within the genus Gulosibacter. These isolates could not be identified reliably using MALDI-TOF mass spectrometry during routine diagnostic work, but partial 16S rRNA gene sequence analysis revealed that they belonged to the genus Gulosibacter. Overall genomic relatedness indices between the draft genome sequences of the three isolates and of the type strains of established Gulosibacter species confirmed that the three isolates represented a single novel Gulosibacter species. A biochemical characterisation yielded differential tests between the novel and established Gulosibacter species, which could also be differentiated using MALDI-TOF mass spectrometry. We propose to formally classify these three isolates into Gulosibacter hominis sp. nov., with 401352-2018 ^T (= LMG 31778 ^T, CCUG 74795 ^T) as the type strain. The whole-genome sequence of strain 401352-2018 ^T has a size of 2,340,181 bp and a G+C content of 62.04 mol%. A Gulosibacter pangenome analysis revealed 467 gene clusters that were exclusively present in G. hominis genomes. While these G. hominis specific gene clusters were enriched in several COG functional categories, this analysis did not reveal functions that suggested a role in the human microbiome, nor did it explain the occurrence of G. hominis in ear infections. The absence of acquired antimicrobial resistance determinants and virulence factors in the G. hominis genomes, and an analysis of publicly available 16S rRNA gene sequences and 16S rRNA amplicon sequencing data sets suggested that G. hominis is a member of the human skin microbiota that may occasionally be involved in opportunistic infections.

Gulosibacter sediminis sp. nov., isolated from Indian Ocean marine sediment

A novel Gram-stain-positive, catalase-positive, oxidase-negative, aerobic, non-motile, rod-shaped bacterium, designated strain YIM M12148^T, was isolated from a marine sediment sample collected from the Indian Ocean. The strain grew optimally at 28 °C, pH 8.0 and in the presence of 1-3 % (w/v) NaCl. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain YIM M12148^T belongs to the genus Gulosibacter, with the highest sequence similarity to Gulosibacter faecalis NBRC 15706^T (96.12 %). The cell-wall sugars of strain YIM M12148^T were rhamnose, ribose, glucose and mannose. The predominant isoprenoid quinones were MK-8 and MK-9. The polar lipids consisted of major amounts of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, one unknown phospholipid and one unknown lipid. Major fatty acids (>5 % of the total) of the novel isolate were anteiso-C_15 : 0, iso-C_15 : 0, iso-C_13 : 0 and anteiso-C_13 : 0. The genomic DNA G+C content of strain YIM M12148^T was 67.15 mol%. On the basis of genotypic and phenotypic data, it is apparent that strain YIM M12148^T represents a novel species of the genus Gulosibacter, for which the name Gulosibacter sediminis sp. nov. is proposed. The type strain is YIM M12148^T (=KCTC 29660^T=DSM 29154^T).