Corynebacterium rhinophilum sp. nov. isolated from the human upper respiratory tract.

Abstract

Twelve strains of a novel Corynebacterium species were cultured from human respiratory samples collected in the USA and Botswana. Five strains underwent detailed phenotypic and chemotaxonomic characterization, while all 12 strains were included in phylogenomic analyses. Optimal growth was observed on brain heart infusion solid medium and in liquid media, including brain heart infusion and tryptic soy broth when supplemented with Tween 80, a source of the fatty acid oleic acid. Cells were Gram-positive, non-spore-forming, non-motile bacilli that exhibited catalase activity but lacked oxidase activity. Major fatty acids were 18 : 1 ω9c (oleic acid) and 16 : 0 (palmitic acid). Analysis of 16S ribosomal RNA gene sequences identified these strains as belonging to the genus Corynebacterium (family Corynebacteriaceae), with the closest relatives being Corynebacterium accolens and Corynebacterium macginleyi. Whole-genome sequencing revealed that the genomes are 2.47-2.62 Mbp in size and have a G+C content of 58.7-59.0 mol%. Average nucleotide identity and in silico DNA-DNA hybridization values for comparisons of these genomes to those of closely related phylogenetic neighbours were 93.19-93.62% and 19.9-36.3%, respectively. These results indicate that these strains represent a novel species of Corynebacterium, for which we propose the name Corynebacterium rhinophilum sp. nov., with the type strain MSK072^T (=DSM 118652^T=JCM 37534^T).