Note: Corynebacterium kroppenstedtii sp. nov., a novel corynebacterium that does not contain mycolic acids

This paper describes the identification and characterization of a novel Corynebacterium species isolated from human sputum. The bacterium, strain CCUG 35717T, was analyzed using phenotypic and molecular taxonomic methods, including 16S rRNA gene sequencing and chemical analysis. Comparative analysis of the 16S rRNA gene sequence demonstrated that the strain represents a new and deeply branching lineage within the genus Corynebacterium sensu stricto, with sequence similarity values of approximately 91-93% to established Corynebacterium species. Notably, chemical analysis revealed the strain lacked mycolic acids, which are typically characteristic of Corynebacterium species. The bacterium is Gram-positive, catalase-positive, facultatively anaerobic, produces acid from glucose, maltose, and sucrose, and shows distinct biochemical properties. Cell wall analysis confirmed the presence of meso-diaminopimelic acid and arabinogalactan, consistent with Corynebacterium. Based on its phylogenetic distinctiveness, absence of mycolic acids, and unique biochemical profile, the authors propose the name Corynebacterium kroppenstedtii sp. nov. for this bacterium, with type strain CCUG 35717T.

Key findings

• C. kroppenstedtii is a novel Corynebacterium species that lacks mycolic acids, a characteristic feature normally present in the genus
• 16S rRNA gene analysis demonstrates the organism forms a deep, isolated lineage within Corynebacterium sensu stricto with sequence divergence >6% from closest relatives
• The bacterium can be biochemically differentiated from other amycolate species (C. amycolatum and Turicella otitidis) by distinct enzyme profiles and carbohydrate fermentation patterns
• The isolate was obtained from human sputum, has a DNA G+C content of 62 mol%, and is sensitive to penicillin and vancomycin