Cutibacterium nasicola sp. nov., isolated from nasal swabs of coal miners.

Abstract

Two Gram-stain-positive, catalase-positive, oxidase-negative, non-spore-forming, aerotolerant anaerobic and non-motile short rod-shaped bacterial strains, designated V947^T and V970, were isolated from nasal swab samples of coal miners. Phylogenetic analyses based on 16S rRNA gene sequences and whole-genome sequences revealed that strains V947^T and V970 represent a distinct lineage within the genus Cutibacterium, most closely related to Cutibacterium avidum ATCC 25577^T (16S rRNA gene sequence similarity of 97.09%). Whole-genome comparative analyses showed that the average nucleotide identity values between the two strains and all validly published species of the genus Cutibacterium with correct nomenclature ranged from 76.55 to 90.26%, while the digital DNA-DNA hybridization values ranged from 21.80 to 40.40%, both of which are well below the accepted thresholds for species delineation. Pangenome analysis identified 711 species-specific gene clusters present in strains V947^T and V970 but absent from all reference type strains of the genus, which were predominantly involved in carbohydrate transport and metabolism, inorganic ion transport and signal transduction mechanisms, suggesting distinct metabolic capabilities and potential for environmental adaptation. These genomic features not only support the delineation of a novel species but also expand the known genomic and functional diversity within the genus Cutibacterium. The predominant cellular fatty acids were iso-C_15:0 and anteiso-C_15:0. The major polar lipids of strain V947^T were diphosphatidylglycerol, phosphatidylinositol and phosphatidylcholine, and the predominant menaquinones were MK-8(H₄) and MK-9(H₆). On the basis of phylogenetic, genomic, chemotaxonomic and phenotypic characteristics, strains V947^T and V970 represent a novel species of the genus Cutibacterium, for which the name Cutibacterium nasicola sp. nov. is proposed. The type strain is V947^T (=CGMCC 1.5844^T=KCTC 59608^T).