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 macacae sp. nov., a novel actinobacterium isolated from Macaca mulatta faeces

A novel Gram-stain-positive, aerobic, non-spore-forming, irregular short rod-shaped actinobacterial strain, designated YIM 102482-1T, was isolated from the faeces of Macaca mulatta. Strain YIM 102482-1T grew optimally at 30–37 °C, at pH 8.0 and in the presence of 1.0–3.0% (w/v) NaCl. Similarly, analysis based on 16S rRNA gene sequences showed that strain YIM 102482-1T was a member of the genus Gulosibacter and most closely related to Gulosibacter feacalis NBRC 15706T (97.6 %), Gulosibacter bifidus NBRC 103089T (97.6 %), Gulosibacter chungangensis KCTC 13959T (96.4 %) and Gulosibacter molinativorax DSM 13485T (96.0 %), respectively. Furthermore, phylogenetic trees based on 16S rRNA gene sequences and genomic sequences demonstrated that strain YIM 102482-1T formed a distinct branch with all type strains of the genus Gulosibacter . The major whole-cell sugars and cellular fatty acids (>10.0 %) were ribose and rhamnose, and anteiso-C15 : 0, iso-C16 : 0 and C16 : 0, respectively. The predominant menaquinone was MK-9, and 2,4-diaminobutyric acid and ornithine were the diagnostic diamino acids in the cell-wall peptidoglycan. The dominant polar lipids consisted of diphosphatidylglycerol, phosphatidylglycerol and unidentified glycolipid. The DNA G+C content of YIM 102482-1T was 63.0 mol%. Based on analysis results of physiological, biochemical and chemotaxonomic data, strain YIM 102482-1T represents a novel species of the genus Gulosibacter , for which the name Gulosibacter macacae sp. nov. is proposed. The type strain is YIM 102482-1T(=DSM 102156T=CCTCC AB 2016023T).